Biomass yield and silage characteristics of elephantgrass (Pennisetum purpureum Schum.) as affected by harvest frequency...

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Title:
Biomass yield and silage characteristics of elephantgrass (Pennisetum purpureum Schum.) as affected by harvest frequency and genotype
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xii, 98 leaves : ill. ; 28 cm.
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English
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Woodard, Kenneth Robert, 1954-
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Energy crops   ( lcsh )
Pennisetum purpureum   ( lcsh )
Silage   ( lcsh )
Dissertations, Academic -- Agronomy -- UF
Agronomy thesis Ph. D
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bibliography   ( marcgt )
non-fiction   ( marcgt )

Notes

Thesis:
Thesis (Ph. D.)--University of Florida, 1989.
Bibliography:
Includes bibliographical references (leaves 93-97).
Statement of Responsibility:
by Kenneth Robert Woodard.
General Note:
Typescript.
General Note:
Vita.
General Note:
Includes abstract.

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University of Florida
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All applicable rights reserved by the source institution and holding location.
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oclc - 22460880
notis - AHG1232
sobekcm - AA00004788_00001
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Full Text











BIOMASS YIELD AND SILAGE CHARACTERISTICS OF ELEPHANTGRASS (Pennisetum
purpureum SCHUM.) AS AFFECTED BY HARVEST FREQUENCY AND GENOTYPE












BY

KENNETH ROBERT WOODARD


A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE
REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY



UNIVERSITY OF FLORIDA


1989































Dedicated to my parents
Mark and Mozelle Woodard















ACKNOWLEDGMENTS


The author wishes to express his sincere gratitude to Dr. Gordon

M. Prine, Professor of Agronomy and chairman of the supervisory

committee, for his support and guidance throughout the research

program and for review of this manuscript. Appreciation is further

extended to the members of the supervisory committee, Dr. Douglas B.

Bates and Dr. William E. Kunkle, Assistant and Associate Professors of

Animal Science, and Dr. Loy V. Crowder and Dr. Stanley C. Schank,

Professors of Agronomy, for their contributions to the research

program and manuscript reviews.

Special thanks are given to Thomas Burton and Anthony Sweat for

assisting the author in several phases of this study.

The author wishes to recognize Jeanette Filer, Angelita Mariano,

and Alvin Boning, Animal Science Department, for their endless

patience and invaluable assistance in the laboratory.

The author is grateful to Jose Franca for giving meaning to

several Brazilian articles that were written in Portuguese and cited

in this report.

The author is also grateful to Mrs. Patricia French for typing

the manuscript.

Finally, the author expresses his appreciation to the Gas

Research Institute, Chicago, Illinois, and the Institute of Food and

Agricultural Sciences, Gainesville, Florida, for co-funding this

research.















TABLE OF CONTENTS

PAGE


ACKNOWLEDGMENTS................................................. iii

LIST OF TABLES............................................ v

LIST OF FIGURES................................................. x

ABSTRACT......................................................... xi

CHAPTER 1 INTRODUCTION........................................ 1

CHAPTER 2 BIOMASS YIELD AND QUALITY CHARACTERISTICS OF
ELEPHANTGRASS AS AFFECTED BY HARVEST FREQUENCY
AND GENOTYPE........................................ 3

Introduction........................................ 3
Materials and Methods............................... 5
Results and Discussion.............................. 11
Oven Dry Biomass Yields........................... 11
Crude Protein, In Vitro Organic Matter Digesti-
bility, and Neutral Detergent Fiber............ 15
Winter Survival.................................. 24
Methane Production............................... 26
Animal Performance.............................. 28
Conclusions............ ........................ 30

CHAPTER 3 SILAGE CHARACTERISTICS OF ELEPHANTGRASS AND
ENERGYCANE AS AFFECTED BY HARVEST FREQUENCY AND
GENOTYPE............................................ 32

Introduction........................................ 32
Materials and Methods............................... 33
Results and Discussion.............................. 36
Biomass Characteristics Before Ensiling.......... 36
Silage Characteristics............................ 44
Utilization of Elephantgrass Silage.............. 60
Conclusions......................................... 67

CHAPTER 4 GENERAL SUMMARY AND CONCLUSIONS..................... 69

APPENDIX...... .................................................. 74

LITERATURE CITED................................................ 93

BIOGRAPHICAL SKETCH............................................. 98
















LIST OF TABLES


TABLE PAGE

1 Oven dry biomass yield of elephantgrass genotypes grown
under one, two, and three harvests per year at Green
Acres research farm near Gainesville, FL, during 1986.... 12

2 Oven dry biomass yield of elephantgrass genotypes grown
under one, two and three harvests per year at Green
Acres research farm near Gainesville, FL, during 1987.... 13

3 Crude protein content of elephantgrass genotypes grown
under one, two, and three harvests per year at Green
Acres research farm near Gainesville, FL, during 1986.... 16

4 Crude protein content of elephantgrass genotypes grown
under one, two, and three harvests per year at Green
Acres research farm near Gainesville, FL, during 1987.... 17

5 In vitro organic matter digestibility (IVOMD) of
elephantgrass genotypes grown under one, two, and three
harvests per year at Green Acres research farm near
Gainesville, FL, during 1986............................. 19

6 In vitro organic matter digestibility (IVOMD) of
elephantgrass genotypes grown under one, two, and three
harvests per year at Green Acres research farm near
Gainesville, FL, during 1987............................. 20

7 Ash-free neutral detergent fiber (NDF) content of
elephantgrass genotypes grown under one, two, and three
harvests per year at Green Acres research farm near
Gainesville, FL, during 1986............................. 21

8 Ash-free neutral detergent fiber (NDF) content of
elephantgrass genotypes grown under one, two, and three
harvests per year at Green Acres research farm near
Gainesville, FL, during 1987............................. 22

9 Stand survival of elephantgrass genotypes following the
1986-87 growing seasons with plots harvested one, two,
and three times per year at Green Acres research farm
near Gainesville, FL..................................... 25











TABLE PAGE

10 Average predicted methane production of PI 300086
elephantgrass harvested one, two, and three times per
season at Green Acres research farm near Gainesville,
FL, during the 1986-87 growing seasons.................... 27

11 Dry matter content of elephantgrass and energycane
grown under one, two, and three harvests in 1986 at
Green Acres research farm near Gainesville, FL............ 37

12 Dry matter content of elephantgrass and energycane
grown under one, two, and three harvests in 1987 at
Green Acres research farm near Gainesville, FL............ 38

13 Water soluble carbohydrate (WSCHO) content of
elephantgrass and energycane grown under one, two, and
three harvests in 1987 at Green Acres research farm near
Gainesville, FL.......................................... 40

14 Buffering capacity of PI 300086 elephantgrass and
L79-1002 energycane grown under one, two, and three
harvests in 1987 at Green Acres research farm near
Gainesville, FL.......................................... 42

15 The pH of elephantgrass and energycane silages
made from plants grown under one, two, and three harvests
during 1986 at Green Acres research farm near
Gainesville, FL.......................................... 45

16 The pH of elephantgrass and energycane silages made
from plants grown under one, two, and three harvests in
1987 at Green Acres research farm near Gainesville, FL... 46

17 Lactic acid content of elephantgrass and energycane
silages made from plants harvested one, two, and three
times in 1986 at Green Acres research farm near
Gainesville, FL.......................................... 47

18 Lactic acid content of elephantgrass and energycane
silages made from plants harvested one, two, and three
times in 1987 at Green Acres research farm near
Gainesville, FL.......................................... 48

19 Acetic acid content of elephantgrass and energycane
silages made from plants harvested one, two, and three
times in 1986 at Green Acres research farm near
Gainesville, FL.......................................... 49














20 Acetic acid content of elephantgrass and energycane
silages made from plants harvested one, two, and three
times in 1987 at Green Acres research farm near
Gainesville, FL.......................................... 50

21 Ammoniacal N percentage of total N in PI 300086
elephantgrass and L79-1002 energycane silages made from
plants grown under one, two, and three harvests in 1987
at Green Acres research farm near Gainesville, FL........ 53

22 Lactic acid percentage of total acids in elephantgrass
and energycane silages made from plants grown under one,
two, and three harvests in 1986 at Green Acres research
farm near Gainesville, FL................................ 56

23 Lactic acid percentage of total acids in elephantgrass
and energycane silages made from plants grown under one,
two, and three harvests in 1987 at Green Acres research
farm near Gainesville, FL................................ 57

24 Flieg score of elephantgrass and energycane silages made
from plants grown under one, two, and three harvests in
1986 at Green Acres research farm near Gainesville, FL... 58

25 Flieg score of elephantgrass and energycane silages made
from plants grown under one, two, and three harvests in
1987 at Green Acres research farm near Gainesville, FL... 59

26 Dry matter recovery of elephantgrass and energycane
forages that were stored by ensiling in 1986 at Green
Acres research farm near Gainesville, FL................. 61

27 Dry matter recovery of elephantgrass and energycane
forages that were stored by ensiling in 1987 at Green
Acres research farm near Gainesville, FL................. 62

28 Mean percentage point difference between in vitro
organic matter digestibilities before and after the
ensiling of elephantgrass and energycane which were
gathered from plots harvested one, two, and three times
per year at the Green Acres research farm near
Gainesville, FL, during 1986-87.......................... 63

29 Oven dry biomass yield of elephantgrass genotypes from
single harvests within multiple harvest treatments made
during 1986 at Green Acres research farm near
Gainesville, FL...................... .................... 74


PAGE


TABLE













30 Oven dry biomass yield of elephantgrass genotypes from
single harvests within multiple harvest treatments made
during 1987 at Green Acres research farm near
Gainesville, FL.......................................... 75

31 Crude protein content of elephantgrass genotypes from
single harvests within multiple harvest treatments made
during 1986 at Green Acres research farm near
Gainesville, FL.......................................... 76

32 Crude protein content of elephantgrass genotypes from
single harvests within multiple harvest treatments made
during 1987 at Green Acres research farm near
Gainesville, FL.......................................... 77

33 In vitro organic matter digestibility (IVOMD) of
elephantgrass genotypes from single harvests within
multiple harvest treatments made during 1986 at Green
Acres research farm near Gainesville, FL................. 78

34 In vitro organic matter digestibility (IVOMD) of
elephantgrass genotypes from single harvests within
multiple harvest treatments made during 1987 at Green
Acres research farm near Gainesville, FL.................. 79

35 Ash-free neutral detergent fiber (NDF) content of
elephantgrass genotypes from single harvests within
multiple harvest treatments made during 1986 at Green
Acres research farm near Gainesville, FL................. 80

36 Ash-free neutral detergent fiber (NDF) content of
elephantgrass genotypes from single harvests within
multiple harvest treatments made during 1987 at Green
Acres research farm near Gainesville, FL.................. 81

37 Dry matter content of elephantgrass and energycane from
single harvests within multiple harvest treatments made
during 1986 at Green Acres research farm near
Gainesville, FL........................................... 82

38 Dry matter content of elephantgrass and energycane from
single harvests within multiple harvest treatments made
during 1987 at Green Acres research farm near
Gainesville, FL.......................................... 83

39 Water soluble carbohydrate (WSCHO) content of
elephantgrass and energycane from single harvests
within multiple harvest treatments made during 1987 at
Green Acres research farm near Gainesville, FL............ 84


viii


TABLE


PAGE














40 Buffering capacity of PI 300086 elephantgrass and
L79-1002 energycane from single harvests within
multiple harvest treatments made during 1987 at Green
Acres research farm near Gainesville, FL.................. 85

41 The pH of elephantgrass and energycane silages made with
plants from single harvests within multiple harvest
treatments during 1986 at Green Acres research farm near
Gainesville, FL.......................................... 86

42 The pH of elephantgrass and energycane silages made with
plants from single harvests within multiple harvest
treatments during 1987 at Green Acres research farm near
Gainesville, FL.......................................... 87

43 Lactic acid content of elephantgrass and energycane
silages made with plants from single harvests within
multiple harvest treatments during 1986 at Green Acres
research farm near Gainesville, FL....................... 88

44 Lactic acid content of elephantgrass and energycane
silages made with plants from single harvests within
multiple harvest treatments during 1987 at Green Acres
research farm near Gainesville, FL...................... 89

45 Acetic acid content of elephantgrass and energycane
silages made with plants from single harvests within
multiple harvest treatments during 1986 at Green Acres
research farm near Gainesville, FL....................... 90

46 Acetic acid content of elephantgrass and energycane
silages made with plants from single harvests within
multiple harvest treatments during 1987 at Green Acres
research farm near Gainesville, FL...................... 91

47 Ammoniacal N percentage of total N in PI 300086
elephantgrass and L79-1002 energycane silages made with
plants from single harvests within multiple harvest
treatments during 1987 at Green Acres research farm near
Gainesville, FL.......................................... 92


PAGE


TABLE















LIST OF FIGURES


FIGURE PAGE

1 Climatological data at Gainesville, Florida, for 1986.... 6

2 Climatological data at Gainesville, Florida, for 1987.... 7














Abstract of Dissertation Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Doctor of Philosophy

BIOMASS YIELD AND SILAGE CHARACTERISTICS OF ELEPHANTGRASS (Pennisetum
purpureum SCHUM.) AS AFFECTED BY HARVEST FREQUENCY AND GENOTYPE

By

KENNETH ROBERT WOODARD

August 1989

Chairman: Dr. Gordon M. Prine
Major Department: Agronomy

Elephantgrass (Pennisetum purpureum Schum.) is being evaluated in

Florida as a biomass energy crop and a forage for ruminants. In a 2-year

study conducted on a dry, infertile site and under the subtropical

conditions near Gainesville, the response of this forage to three harvest

frequency regimes was measured. Genotypes evaluated were four "tall"

elephantgrasses (PI 300086, Merkeron, N-43, and N-51), a "dwarf"

elephantgrass ('Mott'), a "semi-dwarf" Pennisetum glaucum x P. purpureum

hybrid (Selection No. 3), and a "tall" Saccharum species of energycane

(L79-1002). To determine if these grasses could be stored as silage, the

fresh chopped plant materials of PI 300086, Merkeron, Mott, and L79-1002

were hand-packed into 20-liter plastic containers lined with two 4-mil

plastic bags.

Mean dry biomass yields for the four tall elephantgrasses during

1986-87 were 27, 24, and 18 Mg ha-1 yr-1 for one, two, and three harvests

yr-1, respectively. In vitro organic matter digestibilities (IVOMD) were

40, 49, and 55% while crude protein (CP) contents were 4.0, 5.8, and 7.9%











(dry basis), respectively. Ash-free neutral detergent fiber (NDF)

contents were 81, 76, and 74% (dry basis). Predicted methane production

ha-1 yr- for PI 300086 was similar for all harvest treatments.

For Mott dwarf elephantgrass, 2-year mean dry biomass yields were 13,

12, and 11 Mg ha-1 yr-1 for one, two, and three harvests yr- ,

respectively. Mean IVOMDs were 40, 54, and 57% while CP contents were 5.3,

7.1, and 9.6%, respectively. Two-year NDF means were 77, 73, and 70%.

Merkeron, N-43, N-51, Mott, and L79-1002 survived the experimental

conditions. Genotype PI 300086 survived during 1986-87; however, major

stand losses occurred over the 1987-88 winter following the second

growing season in plots harvested multiple times. An almost complete

loss of stand occurred in Selection No. 3 plots.

Mean pH values ranged from 3.8 to 4.0 for the tall elephantgrass

silages made from plants harvested at the different frequencies. The

highest pH values were obtained from silages made from immature Mott

plants harvested three times yr-1 (2-year mean was 4.3). Water soluble

carbohydrate contents of fresh elephantgrass forages (range: 2.6 to

8.4%, dry basis) tended to increase with more frequent harvesting.

Buffering capacities of fresh PI 300086 and L79-1002 biomass were low and

also increased with more frequent harvesting. Lactic acid was the major

end-product of fermentation in most silages with the exception of those

made from immature Mott and L79-1002 plants where lactic and acetic acids

were both major components. Butyric acid levels were negligible in all

silages. Dry matter recoveries for all silages ranged from 84 to 98%.

Silage IVOMDs were mainly dependent on the IVOMDs of the standing forages

at the time of harvest.















CHAPTER 1
INTRODUCTION


Elephantgrass or napiergrass (Pennisetum purpureum Schum.) is a

perennial erect bunchgrass that was first cultivated in South Africa

around 1910 (Van Zyl, 1970). Since then elephantgrass research has

been conducted throughout the tropics and warmer subtropics. The

purpose of most of the past research was to evaluate this grass as a

forage for ruminants.

In recent times new objectives have surfaced which focus on

elephantgrass as a renewable biomass energy source. The Arab-OPEC oil

embargo of 1973-74, which caused widespread fuel shortages in the USA,

was the initial motivating force behind the creation of biomass energy

research programs in many parts of this country.

In Florida, energy programs were implemented in the early 1980s

to evaluate different plant species for biomass production. Of over

150 field tested species, elephantgrass was chosen by agronomists at

the University of Florida as one of three plant species for intensive

evaluation (Smith, 1984). Elephantgrass was selected because of its

ability to produce large amounts of plant biomass per unit land area.

Record dry matter yields have been reported at two locations in the

tropics that exceed 80 Mg ha-1 yr-1 (Watkins and Severen, 1951;

Vicente-Chandler et al., 1959). Other desirable attributes include a

positive yield response to very high rates of nitrogen fertilization,

the perennial nature of the plant, and the tolerance to severe drought












stress with subsequent compensatory growth when favorable growing

conditions prevail.

Other developments in recent years have renewed interest in

elephantgrass. The development of "dwarf" strains of elephantgrass by

researchers at Tifton, Georgia, has increased its potential in

ruminant animal production. Research by Boddorff and Ocumpaugh (1986)

has shown dwarf genotypes to be superior in overall plant quality to

that of "tall" Pennisetum hybrids. Furthermore, over several years

forage agronomists at Gainesville have consistently reported average

daily liveweight gains of one kg from steers grazing 'Mott' dwarf

elephantgrass for prolonged summer-fall periods ranging from 126 to

177 days (Mott and Ocumpaugh, 1984; Sollenberger et al., 1988). Also,

with improvements in mechanical forage harvesters, the highly

productive tall genotypes can be more effectively harvested as

greenchop or silage.

The following research was co-funded by the Gas Research

Institute, Chicago, Illinois, and the Institute of Food and

Agricultural Sciences, Gainesville, Florida. It consisted of an

elephantgrass study that was conducted over two growing seasons on an

infertile, dry location near Gainesville, Florida, where conditions

may be classified as the colder subtropics. The primary objectives

were to measure the effects of harvest frequency and genotype on

biomass yield, forage quality, and stand persistence and to determine

if elephantgrass could be successfully stored by ensiling.















CHAPTER 2
BIOMASS YIELD AND QUALITY CHARACTERISTICS OF ELEPHANTGRASS
AS AFFECTED BY HARVEST FREQUENCY AND GENOTYPE


Introduction


Elephantgrass is well known throughout much of the wet tropics for

its prolific growth habit and usage as a forage for livestock.

Presently, this C-4 grass is being intensively evaluated by agronomists

in Florida as a renewable biomass source for methane production (Prine

et al., 1988). Before elephantgrass can become a viable biomass

source, however, more must be known about the performance of existing

genotypes under different cultural conditions, particularly in the

colder subtropical climate of North Central Florida.

Two factors that strongly affect elephantgrass performance are

harvest frequency and genotype. Mislevy et al. (1986) reported dry

biomass yields of 52.2 and 17.0 Mg ha-1 yr-1 for PI 300086

elephantgrass when harvested one and two times per season,

respectively, at Ona, Florida. At Gainesville, Florida, Calhoun and

Prine (1985) showed a curvilinear increase in annual biomass yield of

PI 300086 elephantgrass with increased time between harvests (6, 8,

12, and 24 weeks). They also noted that plants growing under the 24-

week harvest interval regime were more winter-hardy thcn those growing

under the other three shorter intervals. Also working with

PI 300086 elephantgrass at Gainesville, Shiralipour and Smith (1985)











reported declining methane yield per volatile solid (VS), with

advancing plant maturity. For plant ages 75, 150, and 315 days, they

obtained methane yields of 0.38, 0.30, and 0.25 standard m3 kg-1 VS.

In Puerto Rico, Vicente-Chandler et al. (1959) obtained dramatic

increases in annual biomass yields and declining crude protein

contents by increasing the length of harvest interval (40-, 60-, and

90-day intervals). Arroyo-Aguilu and Oporta-Tellez (1980) observed

diminishing crude protein and increasing neutral detergent fiber

levels in Merker elephantgrass with advancing plant maturity. In

Malaysia, Wong and Sharudin (1986) reported in vitro dry matter

digestibility values of 56, 50, and 44% for elephantgrass forage

harvested at 4-, 8-, and 12-week intervals. Velez-Santiago and

Arroyo-Aguilu (1981) working with seven elephantgrass genotypes

reported declining crude protein levels and increasing biomass yields

with decreasing harvest frequency. Although all genotypes responded

similarly to the effect of harvest frequency, they observed

differences among genotypes in biomass yield, crude protein, and

neutral detergent fiber concentrations. At Gainesville, Prine and

Woodard (1986) evaluated several tall elephantgrass genotypes under

full-season growth. Differences in biomass yield, lodging rate, and

winter survival were observed among genotypes. The genotype PI 300086

often produced the highest biomass yield and was lodge resistant. It

tended, however, to winterkill. Other high-yielding genotypes

including Merkeron, N-51, N-43, and N-13 were much more cold tolerant.

The purpose of the following study was to measure the effects of

harvest frequency and genotype on biomass yield, forage quality, and








5


winter survival in the colder subtropical area of Gainesville,

Florida.


Materials and Methods


An elephantgrass biomass study was conducted over two growing

seasons (1986-87) at the Green Acres University of Florida Research

Farm approximately 20 km northwest of Gainesville, Florida. The soil

at the site was a well-drained Arredondo fine sand (loamy, siliceous,

hyperthermic, Grossarenic Paleudults). Soil organic matter contents

ranged from 1.0 to 1.5%.

Weekly temperature, precipitation, and solar radiation data for

Gainesville are shown in Fig. 1 for 1986 and Fig. 2 for 1987. The

estimated dates of first and last freeze occurrence (50% probability)

for the area are 28 November and 2 March, respectively (Bradley,

1983).

A factorial experiment with a split-plot design was planted in

December 1985, using mature stem cuttings that were horizontally planted

in a furrow. Main plots consisted of harvesting elephantgrass one, two,

and three times per season while subplots were used to compare different

genotypes including four "tall" elephantgrasses (PI 300086, Merkeron, N-

51, and N-43). Also included was a tall-growing energycane (L79-1002)

which is a cross between a commercial sugarcane variety (CP 52-68) and a

wild Saccharum species (Tianan 96) from Argentina that was made in

Louisiana (Giamalva et al., 1984). The four tall elephantgrasses were

previously collected in 1980. They were among 40 genotypes that were

selected as entries in an elephantgrass observation nursery which was









6





AVERAGE WEEKLY TEMPERATURE


M WEEKLY TOTAL PRECIPITATION
leaANNUAL TOTAL 1329
100


140

120

100

80-


00



0

Jan b r Apr May Jun Ju Aug e Ot o

I ERAGE WEEKLY SOLAR RADIATION
20 ANNUAL TOTAL 6310
220
200
100
100
140
120





so --------e- cN-D
40

20

Jan Feb Mar AM MaJ Jul Aug e1 Oct Nov D~c


Fig. 1. Climatological data at Gainesville, Florida, for 1986.
















.C AVERAGE WEEKLY TEMPERATURE
40




30







MIN






Jn Feb Mar A May Jun Jul Aug Se Oct Nov Do

WEEKLY TOTAL PRECIPITATION
RH ANNUAL TOTAL 115n
160

100

140

120

100





40

20


Jan Feb Ma Apr May Jun Jul Aug sop Oct Nov D0o

AWERAQE WEEKLY SOLAR RADIATION
ANNUAL TOTAL 741
220

200
100




140



20 A)A


SFb M Apr My Jun Jul Aug t N



Ja" fb Mw Aor May Jun Jul Aug Se0 Oct Now Dee


Fig. 2. Climatological data at Gainesville, Florida, for 1987.












planted in Gainesville that year. The original planting materials of

PI 300086 elephantgrass were collected at the USDA SCS Plant Materials

Center at Brooksville, Florida. Merkeron, N-51, and N-43 were

collected from the Georgia Coastal Plain Station at Tifton. The

genotype N-51 had been growing on the station as an escape for over 35

years (Prine et al., 1988). Merkeron is a tall hybrid that resulted

from a dwarf x tall elephantgrass cross made by G. W. Burton in 1941

(Hanna, 1986). In the present study the four tall elephantgrasses and

the energycane were grown together at one location.

A dwarf elephantgrass ('Mott') and a semi-dwarf Pennisetum hybrid

[Selection No. 3 (Pennisetum glaucum (L.) R. Br. x Pennisetum

purpureum Schum.)] were planted about 60 m away at another location

under the same split-plot design. Mott (formerly N-75) was named in

honor of the late Dr. Gerald 0. Mott, Professor of Agronomy at the

University of Florida, who along with Dr. W. R. Ocumpaugh and their

students conducted the initial research that showed this dwarf strain

to possess unusually high forage quality (Sollenberger et al., 1988).

Mott was selected by W. W. Hanna in 1977 from among a selfed progeny

of Merkeron elephantgrass (Hanna, 1986). Selection No. 3 is a sterile

interspecific hybrid from a cross between Mott elephantgrass as the

male parent and 23DA dwarf pearlmillet as the female parent (Schank

and Dunavin, 1988).

All treatment combinations at both locations were completely

randomized in four blocks. A plot consisted of five rows. Plot row

length was 8 m while between-row width was 0.9 m. To avoid












competition between harvest frequencies and to facilitate mechanical

harvesting, there were 1.8 and 2.7 m alleys separating main plots.

In the early spring of 1986, clump pieces were transplanted into

the plots where plants failed to emerge. The plots were then

irrigated three times during April and May to ensure an almost

complete stand. This was the only irrigation the plots received

during the entire study.
-1-1
All plots received 336 kg N ha-1 yr-1 in a 4-1-2 ratio with P205
-1
and K20. Plots harvested one time yr received the total annual rate

of fertilizer in a single spring application. The annual rate was

split into two equal spring and summer applications for plots

harvested two times whereas plots harvested three times received three

equal spring, summer, and early fall applications.

During both years the harvest period for main plots cut one time

per season was the third week of November. Plots cut two times were

harvested in the first week of August and the third week of November.

Plots cut three times were harvested in the first weeks of July and

September and the fourth week of November.

A 6-m portion of the center row was harvested at a 10- to 15-cm

cutting height from each plot to determine dry biomass yield. The

tall grasses were mechanically harvested with a John Deere model 3940

forage harvester (Deere and Co., Moline, IL). Short grasses could not

be effectively harvested with the forage harvester. They were cut

down with a Stihl model FS 96 brushcutter (Stihl Inc., Virginia Beach,

VA) and then chopped using the forage harvester. Subsamples weighing

approximately 1.5 kg were collected from the fresh chopped biomass and











air-dried at 600C. After drying, the subsamples were taken

individually from the dryer and weighed immediately to compute dry

matter percentages. A "grab" sample from each subsample was then

ground in a Wiley mill (1-mm mesh screen) prior to analysis at the

University of Florida Forage Evaluation Support Laboratory at

Gainesville, Florida. Also, collected from the 6-m portion of row

were fresh 2 to 3 kg subsamples of chopped PI 300086 elephantgrass

from two blocks for each harvest (six harvests yr- 1). These samples

were frozen and sent to the Bioprocess Engineering Research Laboratory

at Gainesville to determine methane potential. Due to limited

resources at the laboratory, however, one block sample was analyzed in

triplicate. Methane potential was estimated by bioassay procedures

outlined by Owen et al. (1979). Methane yields were calculated after

a 20-day fermentation period.

Nitrogen analysis involved an aluminum block digestion of the

biomass material (Gallaher et al., 1975) followed by an automated

colorimetric determination of total N by a Technicon Auto Analyzer

(Technicon Instruments Corp., Tarrytown, NY). Crude protein content

(dry basis) was computed by multiplying the percent total N by 6.25.

The modified two-stage technique by Moore and Mott (1974) was used to

determine in vitro organic matter digestibility. Neutral detergent

fiber (ash-free) concentrations were determined using the procedure by

Van Soest and Wine (1967) with modifications suggested by Golding et

al. (1985).

For each of the response variables reported on in this Chapter,

with the exception of stand survival, the observations from the single












harvests within a multiple harvest treatment for each genotype were

averaged or summed (depending on the parameter) into a single

observation before statistical analyses were conducted. The means for

most of the response variables from the single harvests are shown in

tables contained in the Appendix.

Analysis of variance was performed by using the general linear

model procedure of the Statistical Analysis System (SAS Institute

Inc., 1982). When the F-test for treatment effects showed

significance at the 5% level, this analysis was followed by Duncan's

multiple range test (DMRT) to compare genotypes. Orthogonal

polynomial procedures were used to determine the nature of the

response over harvest frequencies. Statistical analyses were computed

separately for the tall and short genotypes. The DMRT notations for

tall genotypes are the usual a, b, and c letters, while the notations

for the two short genotypes are letters x and y. Analysis of variance

was not performed on values estimating methane potential because of

limited observations.


Results and Discussion


Oven Dry Biomass Yields


Differences in dry biomass yield did not occur among the four

"tall" elephantgrasses (PI 300086, Merkeron, N-43, and N-51) in either

year (Tables 1 and 2). In 1986, yields for the tall-growing L79-1002

energycane were inferior to the tall elephantgrasses, but the

following season differences did not occur. For all tall genotypes in

both years, the biomass yields decreased as the frequency of harvest











Table 1. Oven dry biomass yield of elephantgrass genotypes grown
under one, two, and three harvests per year at Green Acres
research farm near Gainesville, FL, during 1986.


Oven dry biomass yield
Harvests in 1986
Genotype Growth type 1 2 3 Average

Mg ha-1

PI 300086 tall 30.3 29.7 21.8 27.3a

Merkeron tall 31.9 27.7 21.4 27.Oa

N-43 tall 28.1 27.3 19.2 24.9a

N-51 tall 26.9 27.6 18.0 24.1a

L79-1002t tall 19.6 18.7 14.3 17.5b

Overall average 27.4 L**Q** 26.2 18.9



Selection No. 3 semi-dwarf 19.2 17.7 11.9 16.3x

Mott dwarf 15.2 14.8 11.8 13.9y

Overall averageT 17.2 L** 16.2 11.8


tEnergycane (Saccharum spp.).

tPearlmillet x elephantgrass hybrid.

Means in the same column followed by the same letter are not
different at the 5% level according to DMRT.

TLinear (L) and/or quadratic (Q) effects are significant over harvest
treatments; P<0.01 (**) or P<0.05 (*).











Table 2. Oven dry biomass yield of elephantgrass genotypes grown
under one, two and three harvests per year at Green Acres
research farm near Gainesville, FL, during 1987.


Oven dry biomass yield
Harvests in 1987
Genotype Growth type 1 2 3 Average"

Mg ha-1

PI 300086 tall 23.6 20.3 12.9 18.9a

Merkeron tall 26.3 20.8 16.2 21.1a

N-43 tall 24.3 20.6 14.9 19.9a

N-51 tall 21.2 18.1 16.1 18.5a

L79-1002t tall 21.7 17.9 13.7 17.8a

Overall average 23.4 L** 19.5 14.8

-------------------------------------------------------

Selection No. 3* semi-dwarf 3.2 4.1 6.2 4.5y

Mott dwarf 10.5 9.2 9.8 9.8x

Overall average 6.9 6.6 8.0


tEnergycane (Saccharum spp.).

tPearlmillet x elephantgrass hybrid.

Means in the same column followed by the same letter are not
different at the 5% level according to DMRT.

TLinear (L) and/or quadratic (Q) effects are significant over harvest
treatments; P<0.01 (**) or P<0.05 (*).











increased. The 2-year average yields for the four tall

elephantgrasses with one, two, and three harvests yr-1 were 27, 24,

and 18 Mg ha-1 yr-1 respectively.

In 1986, the dry biomass yields for the "short" grasses

(Selection No. 3 and 'Mott') decreased with more frequent harvests;

however, trends were not found the following season. Selection No. 3

was superior in yield to Mott in 1986, but Mott yields were more than

double those obtained from Selection No. 3 in 1987. That year,

Selection No. 3 plants in all plots began to rapidly deteriorate, thus

resulting in reduced biomass yield. Two-year average yields for Mott

-1 -1
elephantgrass were 13, 12, and 11 Mg ha1 yr for one, two, and three

harvests yr-1 .

Reduction of biomass yield with increased frequency of harvest is

consistent with several reports in the literature (Watkins and

Severen, 1951; Vicente-Chandler et al., 1959; Velez-Santiago and

Arroyo-Aguilu, 1981; Calhoun and Prine, 1985). In the present study,

the yield advantage of full-season growth was probably due to the

extended uninterrupted linear growth phase. At Gainesville, Calhoun

(1985) reported the linear growth phase of dry matter accumulation for

PI 300086 elephantgrass to be about 170 days with a crop growth rate
-2 -1
of 23 g m2 d1. When this growth phase is interrupted as with

harvesting multiple times per season, the reduction in annual biomass

yield can be attributed in part to the uncollected solar energy during

the period between a harvest (canopy removal) and complete vegetative

ground cover of the next ratoon growth phase. Consequently, the more












interruptions made during the season, the lower the annual biomass

yield.

The biomass reduction from one to two harvests yr-1 obtained from

the tall elephantgrass group in the present study (11%) was much

smaller than those Mislevy et al. (1986) reported at Ona, Florida (67

and 69%). Contrastingly, in Puerto Rice--which has a full 12-month

growing season--Samuels et al. (1983) reported higher annual dry

biomass yields from elephantgrass harvested two times yr-1 as compared

to harvesting one time. However, as the harvest frequency increased

to three and six cuts per season, the yields declined. For one, two,

three, and six harvests yr- they reported annual dry biomass yields

of 58, 74, 56, and 27 Mg ha-1, respectively.

The biomass yields from the present study are somewhat lower than

those from the reports cited earlier. However, given the drought,

infertile soils, the nonirrigated conditions, and the colder

subtropical climate at the experimental site, the biomass yields from

this study should be considered substantial.


Crude Protein, In Vitro Organic Matter Digestibility, and Neutral
Detergent Fiber

Differences among tall grass genotypes in crude protein (CP)

content did not occur in either year (Tables 3 and 4). The averages

(over harvest frequency) for the tall grasses ranged from 5.7 to 6.2%,

dry basis. The CP levels increased linearly with increasing frequency

of harvest. The 2-year average CP contents for the four tall

elephantgrasses were 4.0, 5.8, and 7.9% for one, two, and three

harvests per season, respectively.











Table 3. Crude protein content of elephantgrass genotypes grown under
one, two, and three harvests per year at Green Acres
research farm near Gainesville, FL, during 1986.


Crude protein
Harvests in 1986
Genotype F-test 1 2 3 Average"

%, dry basis

PI 300086 3.5 5.6 7.9 5.7a

Merkeron 3.9 5.3 8.1 5.8a

N-43 3.8 6.9 7.9 6.2a

N-51 3.7 5.3 8.2 5.7a

L79-1002t 3.9 5.5 7.8 5.7a

Overall average L** 3.8 5.7 8.0



Selection No. 3t L** 4.3x 7.5x 9.7x 7.1

Mott L** 4.7x 6.9x 8.8y 6.8

Overall average 4.5 7.2 9.2


tEnergycane (Saccharum spp.).

tPearlmillet x elephantgrass hybrid.

Means in the same column followed by the same letter are not
different at the 5% level according to DMRT.

Linear (L) and/or quadratic (Q) effects are significant over harvest
treatments; P<0.01 (**) or P<0.05 (*).











Table 4. Crude protein content of elephantgrass genotypes grown under
one, two, and three harvests per year at Green Acres
research farm near Gainesville, FL, during 1987.


Crude protein
iHarvests in 1987
Genotype F-test 1 2 3 Average

%, dry basis

PI 300086 4.0 6.1 7.5 5.9a

Merkeron 4.5 5.9 7.5 6.0a

N-43 4.3 5.5 8.4 6.1a

N-51 4.5 5.6 7.7 6.0a

L79-1002t 4.5 5.7 7.3 5.8a

Overall average L** 4.4 5.8 7.7



Selection No. 3

Mott L** 5.8 7.3 10.4 7.8


tEnergycane (Saccharum spp.).

tPearlmillet x elephantgrass hybrid.

Means in the same column followed by the same letter are not
different at the 5% level according to DMRT.

"Linear (L) and/or quadratic (Q) effects are significant over harvest
treatments; P<0.01 (**) or P<0.05 (*).












For the short grasses, CP levels also increased with more

frequent harvests. The 2-year average CP contents for Mott

elephantgrass were 5.3, 7.1, and 9.6% for one, two, and three harvests

yr- respectively. Laboratory analyses were discontinued for

Selection No. 3 in 1987 due to herbage deterioration and subsequent

plant death.

In the overall analysis of in vitro organic matter

digestibilities (IVOMD), an interaction occurred between genotype and

harvest frequency in both years for the tall grass group (Tables 5 and

6). When L79-1002 energycane was deleted from the data set, the

interaction was not significant. Merkeron, N-43, and N-51

elephantgrasses did not differ in IVOMD in either season. The

genotype PI 300086 was significantly lower the first season but did

not differ from the other tall elephantgrasses the second season. The

IVOMDs for the elephantgrasses and energycane increased with the more

frequent harvests. The 2-year average IVOMDs for the four

elephantgrass genotypes were 40, 49, and 55% for the one, two, and

three harvests yr- respectively.

In 1986, differences in IVOMD did not occur between Selection No. 3

and Mott genotypes. Also, IVOMD levels increased with more frequent

harvests. The 2-year average IVOMDs for Mott elephantgrass were 40,
-1
54, and 57% for one, two, and three harvests yr- respectively.

Similar ash-free neutral detergent fiber (NDF) values were

obtained from the tall elephantgrasses, though there was a tendency

for PI 300086 to be slightly higher than the others (Tables 7 and 8).

The NDF levels decreased with more frequent harvests; however, the












Table 5. In vitro organic matter digestibility (IVOMD) of
elephantgrass genotypes grown under one, two, and three
harvests per year at Green Acres research farm near
Gainesville, FL, during 1986.


IVOMD
Harvests in 1986
Genotype F-test 1 2 3 Averages



PI 300086 37 47 55 46b

Merkeron 41 49 56 48a

N-43 39 52 56 49a

N-51 40 49 56 48a

Overall average L** Q** 39 49 56

L79-1002t L** Q* 40 47 50 46



Selection No. 3* L** Q** 44x 56x 56x 52

Mott L** Q** 43x 55x 58x 52

Overall average 44 55 57


tEnergycane (Saccharum spp.).

tPearlmillet x elephantgrass hybrid.

Means in the same column followed by the same letter are not
different at the 5% level according to DMRT.

Linear (L) and/or quadratic (Q) effects are significant over harvest
treatments; P<0.01 (**) or P<0.05 (*).











Table 6. In vitro organic matter digestibility (IVOMD) of
elephantgrass genotypes grown under one, two, and three
harvests per year at Green Acres research farm near
Gainesville, FL, during 1987.


IVOMD
Harvests in 1987
Genotype F-test 1 2 3 Average"



PI 300086 40 47 54 47a

Merkeron 42 50 55 49a

N-43 40 49 55 48a

N-51 42 47 55 48a

Overall average L** 41 48 55

L79-1002t L** 46 47 50 48



Selection No. 3

Mott L** Q** 36 53 56 48


tEnergycane (Saccharum spp.).

tPearlmillet x elephantgrass hybrid.

Means in the same column followed by the same letter are not
different at the 5% level according to DMRT.

Linear (L) and/or quadratic (Q) effects are significant over harvest
treatments; P<0.01 (**) or P<0.05 (*).










Table 7. Ash-free neutral detergent fiber (NDF) content of
elephantgrass genotypes grown under one, two, and three
harvests per year at Green Acres research farm near
Gainesville, FL, during 1986.


NDF
Harvests in 1986
Genotype F-testl 1 2 3 Averages

%, dry basis

PI 300086 83 78 76 79a

Merkeron 81 76 73 77bc

N-43 81 75 74 77c

N-51 82 77 74 77b

Overall average L** Q** 82 77 74

L79-1002t 77 78 77 77



Selection No. 3t 76 72 68 72y

Mott 76 73 70 73x

Overall average L** 76 73 69


tEnergycane (Saccharum spp.).

tPearlmillet x elephantgrass hybrid.

Means in the same column followed by the same letter are not
different at the 5% level according to DMRT.

TLinear (L) and/or quadratic (Q) effects are significant over harvest
treatments; P<0.01 (**) or P<0.05 (*).











Table 8. Ash-free neutral detergent fiber (NDF) content of
elephantgrass genotypes grown under one, two, and three
harvests per year at Green Acres research farm near
Gainesville, FL, during 1987.


NDF
Harvests in 1987
Genotype F-testT 1 2 3 Average

%, dry basis

PI 300086 L** 79a 78a 76b 78

Merkeron L** Q* 79a 75b 75c 76

N-43 L** 80a 76b 74c 77

N-51 L** 80a 77a 74c 77

L79-1002t L** 72b 76ab 78a 75

Overall average 78 76 75



Selection No. 3

Mott L** 78 72 70 73


tEnergycane (Saccharum spp.).

tPearlmillet x elephantgrass hybrid.

Means in the same column followed by the same letter are not
different at the 5% level according to DMRT.

TLinear (L) and/or quadratic (Q) effects are significant over harvest
treatments; P<0.01 (**) or P<0.05 (*).












magnitude of the decline was small. The 2-year average NDF

concentrations for the four tall elephantgrasses were 81, 76, and 74%

(dry basis) for one, two, and three harvests yr-1, respectively. For

the energycane (L79-1002), NDF levels were unchanged over harvest

treatments in 1986 while the levels surprisingly increased linearly

with more frequent harvests the following season.

Selection No. 3 and Mott genotypes differed slightly in NDF

during 1986. The NDF levels decreased with increasing cutting

frequency. The 2-year average NDF concentrations for Mott were 77,

73, and 70% for one, two, and three harvests yr-1, respectively.

In general, the quality of elephantgrass forage in terms of CP,

IVOMD, and NDF, becomes more favorable as the number of harvests per

season increases. With more frequent harvesting of both tall and

short elephantgrasses, CP and IVOMD levels increase while NDF

concentrations decline. Among the four tall elephantgrasses,

PI 300086 had a tendency to be slightly lower in IVOMD and higher in

NDF than the others.

Although direct statistical comparisons between tall and short

elephantgrasses cannot be made in this study due to different, but

similar, plot locations, some interesting trends are worth noting.

Crude protein averages recorded for Mott were generally one to two

percentage points higher than the average values recorded for the tall

types. Averages for IVOMD were one to two percentage points higher

under three harvests per season. With two harvests per season, Mott

IVOMD averages were approximately five percentage points higher,

probably the result of a major increase in the stem portion of the












total above-ground parts of tall elephantgrass plants. Also, Mott NDF

levels tended to be from three to five percentage points lower.

The more favorable quality measurements obtained from Mott can be

attributed to the greater fraction of leaves in the total above-ground

portions of dwarf plants and higher stem quality. In Florida,

Boddorff and Ocumpaugh (1986) obtained stem IVOMD values for dwarf

elephantgrass genotypes ranging from 72% in October to 60% in January

while tall hybrid Pennisetum genotypes ranged from 66 to 45% over the

same period. Stem crude protein contents for the dwarf types ranged

from 11% in October to 6% in January (dry basis) compared with 7 to 4%

for the tall hybrids. The leaf blade made up 80% of the total sample

in October for the dwarf genotypes. This was nearly double the value

recorded for the tall hybrids.


Winter Survival


The percent stand survival was recorded after spring growth

initiation in 1988 (Table 9). The elephantgrass PI 300086 survived

the conditions during 1986-87; however, major stand losses occurred

over the 1987-88 winter following the second growing season in plots

harvested multiple times per year. Calhoun and Prine (1985) also

reported major losses in PI 300086 stands with multiple harvest

frequencies at a site near Gainesville.

Merkeron, N-43, N-51, and Mott elephantgrasses and L79-1002

energycane tolerated the harvest frequencies included in the present

study and survived the two winters at Gainesville. Selection No. 3

plots were almost completely void of live plants in the spring of












Table 9. Stand survival of elephantgrass genotypes following the
1986-87 growing seasons with plots harvested one, two, and
three times per year at Green Acres research farm near
Gainesville, FL.


Stand survival
Harvests per year
Genotype F-test# 1 2 3



PI 300086 L** Q** 59b0 8b 8b

Merkeron 84a 75a 81a

N-43 Q** 81a 72a 81a

N-51 80a 69a 81a

L79-1002t 67b 69a 81a



Selection No. 35 Oy ly Oy

Mott 79x 77x 71x


tPercentage of stubble area initiating spring growth on 6 Apr. 1988.

tEnergycane (Saccharum spp.).

Pearlmillet x elephantgrass hybrid.

Means in the same column followed by the same letter are not
different at the 5% level according to DMRT.

Linear (L) and/or quadratic (Q) effects are significant over harvest
treatments; P<0.01 (**) or P<0.05 (*).











1988. Selection No. 3 plants in all plots began to deteriorate

rapidly during the 1987 season. That year a heavy infestation of the

two-lined spittlebug (Prosapia bicincta Say) occurred on Mott and

Selection No. 3. The primary cause of accelerated plant death of

Selection No. 3 was attributed to the spittlebugs.


Methane Production


Results of the bioassays performed on fresh PI 300086

elephantgrass suggest that methane yield kg-l volatile solid (VS)

after a 20-day fermentation period increases with more frequent

harvesting (Table 10). This trend is consistent with the findings of

Calhoun and Prine (1985) and Shiralipour and Smith (1985). However,

the levels of methane yield kg- VS were overall somewhat lower than

those obtained by the reports cited above. Estimated methane

production ha-1 was substantially lower overall compared to values

reported by the former study. This was the result of lower dry

biomass production and methane yield kg-1 VS.

The data suggest that harvesting two times per season results

in slightly higher methane production ha-1; however, large

differences between harvest frequencies were not apparent. It is

possible that the production of biodegradable plant materials per

unit land area (i.e., biodegradable within a reasonable period of

time) is similar for the three harvest frequency regimes. If so,

the biodegradable materials would be more diluted in full-season

growth and concentrated in plants harvested three times per season.

It is also possible that the quantity-quality compromising









Table 10.


Average predicted methane production of PI 300086
elephantgrass harvested one, two, and three times per
season at Green Acres research farm near Gainesville, FL,
during the 1986-87 growing seasons.


Harvests Annual dry Volatile Average Annual methane
per season biomass yield solids methane yield production

Mg ha-1 % std m3 kg-1 VS std m3xl03 ha-1

1 27.0 96.4 0.1851 4.8

2 25.0 95.7 0.217 5.2

3 17.3 94.5 0.277 4.5


tDetermined from one sample per harvest over two seasons.

tMethane yield measured at 15.50C and one atmosphere.











harvest frequency between these two extremes--i.e., harvesting two

times per season--will result in slightly higher methane production.

In contrast, Calhoun and Prine (1985) showed a clear-cut

advantage with full-season growth in annual methane production ha-1

over multiple harvests. In their study, the high values for predicted

methane production ha-1 were mainly due to the large biomass yields of

single annual harvests and the major declines in yield of multiple

cuts. Although full-season growth produced the highest biomass yields

in the present study, major declines in production under two and three

harvests per season did not occur.


Animal Performance


Much research has been conducted with elephantgrass throughout

the tropics and subtropics since the early 1900s. The objectives of

most studies of the past have centered on ruminant nutrition because

of the widespread utilization of this forage as a green chop and

silage feed.

Although direct animal performance data were not collected, it is

reasonable to assume that the forages harvested in the present study

can be used in cattle operations, either totally or in combination

with energy systems, depending on the current market circumstances.

When fed ad libitum as a soilage crop, elephantgrass forages from the

tall genotypes and three harvests per season (2-year average CP and

IVOMD values were 7.9% and 55%, respectively) should result in a

positive energy balance for most classes of cattle (National Research

Council, 1984). Forages grown under two harvests per season (2-year











average CP and IVOMD values were 5.8% and 49%, respectively) should

result in a nutritional level that is near maintenance for some

classes, mature non-lactating cows for example, provided voluntary

intakes are adequate. [The author is assuming that IVOMD is a

reasonable estimate of total digestible nutrient (TDN) content.] In

Venezuela, Arias (1979) measured daily animal intakes with

elephantgrass forage over a 200-day period beginning with 8-month-old

calves. Daily intakes ranged from 2.1 to 3.1 kg DM/100 kg liveweight

with forages gathered at the flowering stage to early vegetative

increase. Daily liveweight gains ranged from -0.1 to 0.8 kg per head.

In Brazil, Goncalez et al. (1979) working with two elephantgrass

cultivars reported daily intakes of 1.9 and 2.3 kg DM/100 kg

liveweight in cattle. The forage in vitro dry matter digestibilities

for the corresponding intake values were 46 and 47%, respectively.

Daily animal performance under ad libitum conditions should be

somewhat higher for Mott dwarf elephantgrass compared to the tall

types. This prediction is based on the improved quality attributes

that were observed in the present study which included higher recorded

values for crude protein and IVOMD and lower values for NDF. Burton

et al. (1969) reported a 20% greater average daily gain for steers

grazing dwarf pearlmillet as compared to those grazing tall types.

Dwarf elephantgrasses may turn out to be inferior to tall types on an

animal product ha-1 basis and under soilage feeding conditions because

the better quality may not make up for its much lower biomass yield.











Conclusions


Elephantgrass produces substantial biomass yields on dry,

infertile sites and under the colder subtropical conditions of North

Central Florida. As the number of harvests per season increases,

biomass yields decline (the yield response of Mott dwarf elephantgrass

may be an exception with the harvest frequencies included in the

present study) while forage crude protein and IVOMD levels and methane

yields kg-l VS increase. Neutral detergent fiber levels gradually

decrease; however, major reductions do not occur.

Variation in survival tolerance to increased harvest frequency

and colder subtropical winters exists among genotypes. The

elephantgrass genotypes Merkeron, N-43, N-51, and Mott, and the

L79-1002 energycane survived the experimental conditions and could be

recommended for planting in North Central Florida. The genotype

PI 300086 elephantgrass was susceptible to winterkill, particularly

when harvested multiple times per season. An almost complete loss of

stand occurred in the semi-dwarf Selection No. 3 (Pennisetum hybrid)

plots during the study. Therefore, PI 300086 and Selection No. 3 are

not suitable for the area.

Two harvests per season appeared to be the best compromise

between biomass quantity and quality (methane yield kg-1 VS), thus

resulting in the highest estimate for methane production ha-1. Since

the other harvest treatments resulted in similar predicted production

levels, the final analysis as to the best harvest regime to use in a

methane production system must come from an evaluation of production

costs and net energy gains.











Finally, the forages resulting from two and three harvests per

season could be utilized, either solely or in combination with energy

production systems, in several types of cattle operations. These

forages should provide an almost complete supply of nutrients required

for certain beef cattle classes such as mature cows and replacement

heifers. For high-producing animals such as lactating dairy cows and

feedlot beef animals, these forages can provide some of the required

nutrients and the needed roughage for maintaining healthy ruminal

functions, when included as a portion of animal diets.















CHAPTER 3
SILAGE CHARACTERISTICS OF ELEPHANTGRASS AND ENERGYCANE
AS AFFECTED BY HARVEST FREQUENCY AND GENOTYPE


Introduction


Elephantgrass was ensiled and fed to cattle in Florida as early

as 1933 by Neal et al. (1935). Using the ensiling process to preserve

thick-stemmed, erect grasses such as elephantgrass is generally the

preferred method over other forms of storage. Making hay with

elephantgrass is not easily accomplished because of the problems

associated with the solar drying of thick stems and the large mass of

plant material produced per unit land area. The accumulation of

forage in the field (stockpiling) is generally an ineffective method

of storage because of the rapid decline in forage quality with

advancing plant age (Gomide et al., 1969).

Reports in the literature on the ensiling of elephantgrass are

not all positive. Davies ensiled chopped elephantgrass in miniature

cement tower silos which held approximately 135 kg of fresh material.

The elephantgrass was 2.5 m tall when harvested and contained 24% dry

matter (DM). Silos were sampled 50 days after packing. He reported

that a 45% loss in DM had occurred during storage which led him to

state that "there appears to be some peculiarity with this grass

[elephantgrass] in that it does not make good silage without the

addition of molasses" (1963, pp. 318-319). Conversely, Brown and

Chavalimu (1985) successfully ensiled 5-week-old elephantgrass











regrowth by hand-packing chopped plant material into two nested

polyethylene bags. Silage sampling took place after 2.5 months of

storage. A 96% DM recovery was reported.

The objectives of the following silage study, which is a

continuation of the experiment previously described in Chapter 2, were

to determine if elephantgrass and energycane gathered under different

harvest frequency regimes could be adequately preserved as silage and

to identify potential problems that could exist in the conversion of

the silage into animal or energy products.


Materials and Methods


Much of the fresh chopped plant materials generated during 1986-87

from the harvest frequency x genotype experiment described in Chaper 2

was ensiled using 20-liter plastic paint pails as portable silos.

Genotypes ensiled included PI 300086, Merkeron, and Mott elephantgrasses

and L79-1002 energycane. The field plots were harvested one, two, and

three times per season. During each harvest, biomass from three blocks

was ensiled for each treatment combination. Tall genotypes were

mechanically harvested with a John Deere model 3940 forage harvester,

which chopped the majority of the plant materials into 2- to 3-cm length

pieces. Mott dwarf elephantgrass could not be effectively harvested

with the forage harvester. It was cut down with a Stihl model FS 96

brushcutter and then chopped using the forage harvester. Each silo

was lined with two, 4-mil thick Ironclad trash compactor plastic

bags (North American Plastics Corp., Aurora, IL), then hand-packed

with 8 to 11 kg of fresh chopped biomass. After filling, the











liner bags were separately tied off with jute string. Each silo was

then weighed.

During field harvesting, subsamples were collected, then air-

dried at 600C to compute DM percentage. These samples were then used

to determine the forage quality parameters reported earlier in Chapter

2. In addition, fresh subsamples were collected in reclosable freezer

bags (2.7-mil thick) and frozen. These samples were used to determine

water soluble carbohydrate content and buffering capacity of original

biomass prior to ensiling.

Ensiling dates corresponded to the harvest periods reported in

Chapter 2. The silos filled during the 1986 season were sampled 10

months after the ensiling dates. The silos filled during the 1987

season were all sampled during the second week of February 1988. The

silos were weighed again just prior to sampling in order to calculate

DM recovery. The weight of a paint pail plus two trash compactor bags

was substrated from the weight of each packed silo before DM recovery

was computed.

During silo sampling, the spoilage that commonly occurred in the

top 4 to 5 cm of the stored biomass was discarded. The remaining

silage was placed in a 114-liter container and thoroughly mixed. A

sample was taken, placed in a freezer bag, and frozen immediately.

Another sample was collected and oven-dried at 600C to compute DM

percentage. It was then ground in a Wiley mill (1-mm mesh screen)

prior to analysis at the University of Florida Forage Evaluation

Support Laboratory at Gainesville, Florida, where the modified two-

stage technique by Moore and Mott (1974) was used to determine in











vitro organic matter digestibility. This procedure was performed on

the original biomass and corresponding silage at the same time, using

the same batch of rumen fluid inoculum.

At a later date, 25 g from each frozen silage sample were placed

in a blender with 225 ml of deionized water. The sample was then

lacerated for 2 minutes and filtered through several layers of

cheesecloth. It was thoroughly pressed to remove as much extract as

possible. This extract was used for silage quality determinations

including pH, acetic, butyric, and lactic acid contents (dry basis),

and ammoniacal N as a percentage of total N.

A Fisher Accumet digital pH meter (Fisher Scientific Corp.,

Pittsburgh, PA) calibrated with pH 4 and 7 buffer solutions, was used

to measure silage pH.

Acetic, butyric, and lactic acid levels were determined using a

Perkin-Elmer Sigma 3B gas chromatograph (Perkin-Elmer, Norwalk, CT).

Chromatograph specifications are as follows: Column packing, GP 10%

SP-1000/1% H3PO4 on 100/120 Chromosorb W AW (Supelco, Inc.,

Bellefonte, PA); Column type, 1.8 m x 2 mm ID glass; Column

temperature, 115-1350C, varied with conditions; Flow rate, 30 ml/min.,

N2; Detector, FID; Sample injection size, 1.0 4l. The gas

chromatograph was calibrated with standards made from Supelco volatile

and non-volatile acid standard mixes. Procedures used to prepare

methyl derivatives of lactic acid from silage extracts were those

outlined by Supelco, Inc. (1985).

Analysis of total N in silage involved an aluminum block

digestion of fresh 5-g samples (Gallaher et al., 1975), followed by a











colorimetric determination using a Technicon Auto Analyzer (Technicon

Instruments Corp., Tarrytown, NY). For ammoniacal N determinations,

silage extracts were analyzed by using an adaptation of the ammonia-

salicylate reaction, followed by Technicon colorimetric procedures

(Noel and Hambleton, 1976).

The phenolsulfuric acid colorimetric procedure by Dubois et al.

(1956) and a Spectronic 20 colorimeter-spectrophotometer (Bausch and

Lomb Inc., Rochester, NY) were used to measure water soluble

carbohydrate content (dry basis) of original biomass before ensiling.

Buffering capacity, expressed as the number of milliequivalents

of NaOH required to raise one kg of biomass DM from pH 4 to 6, was

measured on fresh plant samples before ensiling by methods used by

Playne and McDonald (1966).

For each of the response parameters reported on in this chapter,

the observations recorded for the single harvests within a multiple

harvest treatment for each genotype were averaged into a single

observation before statistical analyses were conducted. The means for

most of the response variables from single harvests are shown in

tables contained in the Appendix.

Statistical procedures used to analyze silage data were the same

as those described in Chapter 2.


Results and Discussion


Biomass Characteristics Before Ensiling


Dry matter (DM) contents for 1986-87 are presented in Tables 11

and 12. Declining DM contents with more frequent harvesting was the











Table 11.


Dry matter content of elephantgrass and energycane grown
under one, two, and three harvests in 1986 at Green Acres
research farm near Gainesville, FL.


Dry matter
Harvests in 1986
Genotype F-testT 1 2 3



PI 300086 L** 33a 26a 19b

Merkeron L** 33a 25a 20ab

L79-1002t L** 31a 24a 21a



Mott L** 29 23 21


Energycane (Saccharum spp.).

Means in the same column followed by the same letter are not
different at the 5% level according to DMRT.

Linear (L) and/or quadratic (Q) effects are significant over harvest
treatments, P<0.01 (**) or P<0.05 (*).











Table 12.


Dry matter content of elephantgrass and energycane grown
under one, two, and three harvests in 1987 at Green Acres
research farm near Gainesville, FL.


Dry matter
Harvests in 1987
Genotype F-testT 1 2 3



PI 300086 L** Q** 37a 26a 20b

Merkeron L** 34b 25a 20b

L79-1002 L** Q* 33b 25a 22a



Mott L** Q** 33 24 25


tEnergycane (Saccharum spp.).


Means in the same column followed by the same
different at the 5% level according to DMRT.


letter are not


Linear (L) and/or quadratic (Q) effects are significant over harvest
treatments, P<0.01 (**) or P<0.05 (*).











general pattern which is in agreement with the results reported by

Vicente-Chandler et al. (1959). Gomide et al. (1969) showed a strong

linear increase in DM content with advancing age of elephantgrass

plants. The harvest frequencies used in the present study provided

plant materials averaging from 19 to 37% DM for ensiling.

The optimum forage DM content for ensiling is generally

considered to be between 28 to 35%. Ensiling forages with DM contents

below 26% are subject to undesirable clostridial fermentation (Harris,

1984). Low DM silages require higher organic acid concentrations and

lower pHs to inhibit the growth and proliferation of Clostridia

bacteria. Clostridial growth is suppressed when the silage DM content

is above 35%. However, excluding oxygen during the packing of high DM

plant materials is more difficult because such materials are of lower

density (Vetter and Von Glan, 1978).

Full-season growth of elephantgrass genotypes contained the lower

levels of water soluble carbohydrates (WSCHO) whereas the more

immature forages from multiple harvest treatments had the higher

levels (Table 13). It should be noted that variations in WSCHO

content existed between individual cuttings within the multiple

harvest regimes. In 1987, the mean WSCHO contents of the tall

elephantgrasses (PI 300086 and Merkeron) for the first, second, and

third cuttings of the three harvests per season treatment were 10.4,

10.6, and 3.0% (dry basis), respectively. With the two harvests

treatment, the levels were 9.9 and 6.0% for the first and second

cuttings, respectively. Similar trends were observed for L79-1002

energycane. Low temperatures just prior to the final harvesting











Table 13.


Water soluble carbohydrate (WSCHO) content of elephantgrass
and energycane grown under one, two, and three harvests in
1987 at Green Acres research farm near Gainesville, FL.


WSCHO
Harvests in 1987
Genotype F-tests 1 2 3

%, dry basis

PI 300086 L** Q* 5.8b0 8.4ab 8.2a

Merkeron L** 4.4b 7.6b 7.9a

L79-1002t L** Q** 9.5a 9.6a 7.1b



Mott L** 2.6 4.6 7.0


tEnergycane (Saccharum spp.).

Means in the same column followed by the same letter are not
different at the 5% level according to DMRT.

Linear (L) and/or quadratic (Q) effects are significant over harvest
treatments, P<0.01 (**) or P<0.05 (*).











period in 1987 caused considerable frost damage, particularly to the

youngest ratoon plants. The low levels of WSCHO were attributed to

cold damage. An interesting inconsistency occurred when the youngest

ratoon plants of PI 300086 and Merkeron elephantgrass (mean WSCHO

content of plants before ensiling was 3.0%, dry basis) from the third

cutting were ensiled. The mean pH value of silages made from these

cold-damaged plants was 3.9--lower than expected--while the mean lactic

acid concentration was 6.8% (dry basis), which was higher than

expected, considering the low WSCHO levels in fresh biomass before

ensiling. Further research is needed before explanations can be given.

The WSCHO content of full-season L79-1002 energycane growth was

substantially higher than those of the elephantgrasses. Although

linear and quadratic effects are significant, it is still unclear how

WSCHO levels in energycane are affected by harvest frequency.

In Brazil, Veiga and Campos (1975) reported an average WSCHO

content of 6.5% (dry basis) for elephantgrass harvested at an advanced

stage of growth. With elephantgrass cut at 55 days of age, Tosi et

al. (1983) reported a mean content of 17.0%.

The buffering capacities of PI 300086 and L79-1002 forages

increased with more frequent harvesting (Table 14). Values measured

for full-season growth were exceptionally low. For both genotypes,

all values were substantially lower than those of other forage crops

reported by Woolford (1984). Woolford reviewed earlier literature and

presented a range of buffering capacities. The highest buffering

capacities shown were from temperate legumes including alfalfa

(Medicago sativa L.) and red clover (Trifolium pratense L.) with











Table 14.


Buffering capacity of PI 300086 elephantgrass and L79-1002
energycane grown under one, two, and three harvests in 1987
at Green Acres research farm near Gainesville, FL.


Buffering capacity
eF-test 1 Harvests in 1987
Genotype F-test 1 2 3

Meq NaOH kg-1 DMt

PI 300086 L** 52a 78a 112b

L79-1002 L** Q** 45a 131a 146a


Milliequivalents of NaOH required to raise the pH of one kg of
biomass DM from 4.0 to 6.0.

Means in the same column followed by the same letter are not
different at the 5% level according to DMRT.

Linear (L) and/or quadratic (Q) effects are significant over harvest
treatments, P<0.01 (**) or P<0.05 (*).










values of 480 and 560 meq NaOH kg-l DM, respectively. Temperate

grasses including orchardgrass (Dactylis glomerata L.), perennial

ryegrass (Lolium perenne L.), and Italian ryegrass (L. multiflorum

Lam.) had intermediate values of 300, 350, and 430 meq, respectively.

Forage corn (Zea mays L.) had the lowest buffering capacity of 200

meq. Woolford suggested that the low buffering capacity partly

explains why corn is easier to ensile than other crops. It is

interesting to note the similarities between elephantgrass,

energycane, and forage corn. These tropical C-4 grass plants have

upright growth habits and large coarse stems where soluble

carbohydrates are stored. The possibility exists that other tropical

grasses with the same morphological features may tend to possess low

buffering capacities.

Tropical forages with low buffering capacities would require

smaller concentrations of lactic acid and other organic acids to be

produced during ensiling in order to reach an ideal low pH where

microbial activity would cease and preservation would occur. Thus,

there would be less of a requirement in standing forages for high

levels of available substrates (WSCHO) needed for a successful

ensilage fermentation.

According to Playne and McDonald (1966) the anionic moiety,

mainly organic acids, of plant biomass contributes 68 to 80% to the

buffering capacity while plant proteins make up 10 to 20%.











Silage Characteristics


Average pH values recorded during both seasons for the tall

elephantgrass silages (PI 300086 and Merkeron) ranged narrowly from 3.8

to 4.0 (Tables 15 and 16). In 1986, pH values for Merkeron increased

linearly with an increase in harvest frequency. Also, during both

seasons pH values for L79-1002 energycane and Mott dwarf elephantgrass

silages increased linearly with more frequent harvesting. The highest

pH values were consistently obtained from silages made from immature

Mott forages gathered from plots harvested three times per season.

During 1986, mean lactic acid contents of PI 300086 and Merkeron

silages (Table 17) ranged from 3.0 to 3.6% (dry basis). The following

season lactic acid levels for these tall elephantgrasses increased as

harvest frequency increased with means ranging from 1.4 to 5.3% (Table

18). Lactic acid contents for L79-1002 energycane silages decreased

linearly with more frequent harvesting during 1986, whereas no effect

was observed the next year. The lowest values were obtained from

L79-1002 silages made from the most immature plants during 1986. Mean

lactic acid contents were fairly constant for Mott silages.

Overall, acetic acid contents generally increased as the harvest

frequency increased (Tables 19 and 20). Mean acetic acid contents for

PI 300086 and Merkeron silages ranged from 0.25 to 1.58% (dry basis).

The higher means were usually obtained from L79-1002 energycane and Mott

elephantgrass silages that were made with immature plant materials from

multiple harvest treatments.

Silages made with plant materials from full-season growth in 1987

had as low or lower pH values than those made from immature plants











The pH of elephantgrass
plants grown under one,
at Green Acres research


and energycane silages made from
two, and three harvests during 1986
farm near Gainesville, FL.


Silage pH
Harvests in 1986
Genotype F-test 1 2 3


PI 300086 3.8a 3.9a 4.Ob

Merkeron L** 3.8a 3.9a 4.Ob

L79-1002t L** 3.8a 3.9a 4.3a



Mott L** 4.0 4.1 4.3


tEnergycane (Saccharum spp.).


Means in the same column followed by the same
different at the 5% level according to DMRT.


letter are not


Linear (L) and/or quadratic (Q) effects are significant over harvest
treatments, P<0.01 (**) or P<0.05 (*).


Table 15.











Table 16.


The pH of elephantgrass and energycane silages made from
plants grown under one, two, and three harvests in 1987 at
Green Acres research farm near Gainesville, FL.


Silage pH
Harvests in 1987
Genotype F-test 1 2 3


PI 300086 3.8a 3.8b 3.8a

Merkeron 3.8b 3.8b 3.9a

L79-1002f L* 3.8a 4.0a 4.0a



Mott L** 4.0 4.2 4.4


tEnergycane (Saccharum spp.).


Means in the same column followed by the same
different at the 5% level according to DMRT.


letter are not


Linear (L) and/or quadratic (Q) effects are significant over harvest
treatments, P<0.01 (**) or P<0.05 (*).












Table 17.


Lactic acid content of elephantgrass and energycane silages
made from plants harvested one, two, and three times in
1986 at Green Acres research farm near Gainesville, FL.


Lactic acid
Harvests in 1986
Genotype F-test 1 2 3

%, dry basis

PI 300086 3.3a 3.0a 3.6a

Merkeron 3.3a 3.4a 3.6a

L79-1002 L** 3.2a 2.8a 0.7b



Mott 3.7 3.3 2.4


tEnergycane (Saccharum spp.).

Means in the same column followed by the same letter are not
different at the 5% level according to DMRT.

Linear (L) and/or quadratic (Q) effects are significant over harvest
treatments, P<0.01 (**) or P<0.05 (*).












Table 18.


Lactic acid content of elephantgrass and energycane silages
made from plants harvested one, two, and three times in
1987 at Green Acres research farm near Gainesville, FL.


Lactic acid
Harvests in 1987
Genotype F-testH 1 2 3

%, dry basis

PI 300086 L** Q* 1.4a 2.6b 5.3a

Merkeron L* 2.2a 4.la 4.5ab

L79-1002t 1.7a 2.2b 3.Ob



Mott 2.3 3.2 2.0


tEnergycane (Saccharum spp.).

Means in the same column followed by the same letter are not
different at the 5% level according to DMRT.

Linear (L) and/or quadratic (Q) effects are significant over harvest
treatments, P<0.01 (**) or P<0.05 (*).











Table 19.


Acetic acid content of elephantgrass and energycane silages
made from plants harvested one, two, and three times in
1986 at Green Acres research farm near Gainesville, FL.


Acetic acid
Harvests in 1986
Genotype F-testT 1 2 3

%, dry basis

PI 300086 0.40a 0.33a 1.49b

Merkeron L* 0.40a 0.75a 1.58b

L79-1002t L** Q* 0.43a 0.65a 2.55a



Mott 0.72 1.45 2.19


tEnergycane (Saccharum spp.).


Means in the same column followed by the same
different at the 5% level according to DMRT.


letter are not


Linear (L) and/or quadratic (Q) effects are significant over harvest
treatments, P<0.01 (**) or P<0.05 (*).












Table 20.


Acetic acid content of elephantgrass and energycane silages
made from plants harvested one, two, and three times in
1987 at Green Acres research farm near Gainesville, FL.


Acetic acid
Harvests in 1987
Genotype F-testH 1 2 3

%, dry basis

PI 300086 0.25b 0.73a 0.69b

Merkeron L** 0.29b 0.77a 1.32ab

L79-1002t L* 0.46a 1.65a 1.71a

--------------------------------------------------

Mott L** Q** 0.28 2.18 2.21


tEnergycane (Saccharum spp.).

Means in the same column followed by the same letter are not
different at the 5% level according to DMRT.

Linear (L) and/or quadratic (Q) effects are significant over harvest
treatments, P<0.01 (**) or P<0.05 (*).











which were gathered from plots harvested multiple times per season.

(This also occurred in 1986.) At first, these data appear to be

inconsistent since the original fresh biomass from mature full-season

plants that year contained the lowest WSCHO concentrations, with

L79-1002 energycane being an exception (Table 13). In addition,

corresponding silages contained lower concentrations of lactic and

acetic acids, compared to those silages made from immature plants.

These results can be explained by using the buffering capacities of

fresh materials that were recorded prior to ensiling in 1987 (Table

14). The fresh forages from full-season plants contained

exceptionally low buffering capacities (i.e., low resistance to

changes in pH). Therefore, lower concentrations of fermentative acids

(lactic and acetic) were needed to reduce the biomass pH to low levels

where bacterial activity stops. Since smaller amounts of these

organic acids were required, lower concentrations of convertible

substrates (WSCHO) in the original forages of full-season growth were

needed to reach that end-point.

Butyric acid concentration and ammoniacal N content, expressed as

a percentage of total biomass N, in silage indicate the extent of

undesirable secondary fermentations by Clostridia bacteria.

Saccharolytic and proteolytic clostridial fermentations can result in

greater losses of dry matter as compared to a lactic acid

fermentation. In addition, end-products formed by clostridial

fermentations can negatively affect voluntary intake in ruminant

animals (Wilkinson et al., 1976).











Mean butyric acid levels (not shown) in PI 300086, Merkeron, and

L79-1002 silages were low during both seasons. Average butyric acid

concentrations in these silages ranged from values near zero to 0.02%

(dry basis). For Mott silages, means ranged from values near zero to

0.12%. No treatment effects were obtained.

Ammoniacal N percentages of total N for PI 300086 elephantgrass

and L79-1002 energycane silages for 1987 are listed in Table 21. Mean

ammoniacal N values for both grasses ranged from 7.7 to 11.0%. For

PI 300086 elephantgrass silages, a linear decrease (P<0.01) in

ammoniacal N percentages with more frequent harvesting was obtained.

Several researchers from Brazil have conducted silage studies with

elephantgrass. Silveira et al. (1979) ensiled direct-cut 62-day

regrowth from four genotypes of elephantgrass. After 150 days of

storage, samples were collected. Mean silage pH values and lactic acid

contents varied from 4.1 to 4.4 and from 5.8 to 7.9% (dry basis),

respectively. Average acetic acid levels ranged from 2.7 to 5.9% (dry

basis). Butyric acid levels reported varied from 0.01 to 0.03% (dry

basis) whereas mean ammoniacal N percentages of total N ranged from 13.3

to 17.6. With elephantgrass ensiled at 9 to 10 weeks of age, Vilela et

al. (1983) reported an average silage pH of 3.9. Mean lactic, acetic,

and butyric acid contents were 1.5, 2.0, and 0.23% (dry basis),

respectively. The mean ammoniacal N level was 17.3% of total N. Veiga

and Campos (1975) ensiled direct-cut elephantgrass at an advanced stage

of growth. The forages used contained 28% DM and 3.6% crude protein

(dry basis). With their controls (no additives) the mean silage pH and

lactic acid content was 3.9 and 2.2% (dry basis), respectively.












Table 21.


Ammoniacal N percentage of total N in PI 300086
elephantgrass and L79-1002 energycane silages made from
plants grown under one, two, and three harvests in 1987 at
Green Acres research farm near Gainesville, FL.


Ammoniacal N
Harvests in 1987
Genotype F-testl 1 2 3



PI 300086 L** 11.0a 10.5a 9.6a

L79-1002 L* Q* 10.la 7.7b 8.6a


Means in the same column followed by the same letter are not
different at the 5% level according to DMRT.

Linear (L) and/or quadratic (Q) effects are significant over harvest
treatments, P<0.01 (**) or P<0.05 (*).











Many attempts have been made to index silage fermentation quality

according to various guidelines. The Breirem and Ulvesli system

outlined by McCullough (1978) characterizes desirable silages as those

having pH values lower than 4.2; lactic and acetic acid contents

ranging from 1.5 to 2.5% and from 0.5 to 0.8% (dry basis),

respectively; butyric acid levels that are below 0.1% (dry basis) and

ammoniacal N levels that do not exceed 5 to 8% of total biomass N.

Using the guidelines above to rank the silages in the present

study, silages made from immature forages harvested from plots cut

three times per season should be considered the lowest in terms of

fermentation quality due mainly to the elevated acetic acid levels and

the higher pH values that were recorded, particularly with those

silages made from L79-1002 energycane and Mott dwarf elephantgrass.

The silages made from full-season growth are the highest in

fermentation quality while those made from plants harvested two times

per season could be considered intermediate. It should be noted that

silage quality expressed in terms of animal performance or methane

yield may result in different "quality" rankings.

The Flieg point system modified by Zimmer and outlined by

Woolford (1984) is a scoring procedure that is used for the quality

indexing of silages. Scores range from zero to 100 where the latter

number is the most desirable. Scoring is based on the relative

proportions of acetic, butyric, and lactic acids to the total sum of

these acids contained in a silage. More points are awarded to a

silage when lactic acid, expressed as a percentage of total acids,










makes up the larger portion whereas fewer points are given when acetic

and butyric acids make up the larger portions of total acids.

In the present study, the mean lactic acid portions of total

acids during both seasons varied from 69 to 90% in PI 300086 and

Merkeron elephantgrass silages for all harvest treatments (Tables 22

and 23). The energycane L79-1002 and Mott elephantgrass silages made

from full-season growth also had high lactic acid percentages.

However, with multiple harvests, lactic acid made up smaller portions

due to the relative increase of acetic acid. From the same tables,

the mean acetic acid percentages of total acids can be closely

approximated by subtracting the mean lactic acid percentages from 100,

since butyric acid contents in silages were negligible. Furthermore,

the statistical results shown in Tables 22 and 23 were the same for

acetic acid percentages. Overall, there was a tendency for the mean

lactic acid percentages to decrease with more frequent harvesting.

Conversely, the acetic acid percentages tended to increase.

Average Flieg scores for PI 300086 and Merkeron silages over all

harvest treatments ranged from 84 to 100 (Tables 24 and 25).

According to the Flieg index system, these scores denote very high

silage quality. Lower scores were associated with silages made from

immature L79-1002 energycane and Mott elephantgrass forages. The

lowest mean score of 51, however, reflects average quality.

From a strict quantitative standpoint, one of the best indicators of

the effectiveness of the ensilage process on the preservation of biomass

is DM recovery. During both seasons, average DM recoveries for all











Table 22.


Lactic acid percentage of total acids in elephantgrass and
energycane silages made from plants grown under one, two,
and three harvests in 1986 at Green Acres research farm
near Gainesville, FL.


Lactic acid
Harvests in 1986
Genotype F-testT 1 2 3

% of total acids-

PI 300086 88a 90a 72a

Merkeron 89a 81a 69a

L79-1002t L** Q** 88a 81a 21b



Mott 82 69 53


Energycane (Saccharum spp.).

hTotal acids include acetic, butyric, and lactic acids.

Means in the same column followed by the same letter are not
different at the 5% level according to DMRT.

Linear (L) and/or quadratic (Q) effects are significant over harvest
treatments, P<0.01 (**) or P<0.05 (*).











Table 23.


Lactic acid percentage of total acids in elephantgrass and
energycane silages made from plants grown under one, two,
and three harvests in 1987 at Green Acres research farm
near Gainesville, FL.


Lactic acid
Harvests in 1987
Genotype F-testT 1 2 3

% of total acids:

PI 300086 86a 78ab 88a

Merkeron L** 87a 84a 77ab

L79-1002t 78b 56b 62b

---------------------------------------------------

Mott L** Q* 89 59 47


tEnergycane (Saccharum spp.).

Total acids include acetic, butyric, and lactic acids.

Means in the same column followed by the same letter are not
different at the 5% level according to DMRT.

"Linear (L) and/or quadratic (Q) effects are significant over harvest
treatments, P<0.01 (**) or P<0.05 (*).












Table 24. Flieg score of elephantgrass
from plants grown under one,
1986 at Green Acres research


and energycane silages made
two, and three harvests in
farm near Gainesville, Fl.


Total Flieg points
Harvests in 1986
Genotype F-test" 1 2 3


PI 300086 99a 100a 87a

Merkeron 100a 96a 84a

L79-1002t L** Q** 100a 97a 51b

--------------------------------------------------

Mott 84 84 65


tEnergycane (Saccharum spp.).

Means in the same column followed by the same letter are not
different at the 5% level according to DMRT.

"Linear (L) and/or quadratic (Q) effects are significant over harvest
treatments, P<0.01 (**) or P<0.05 (*).











Flieg score of elephantgrass
from plants grown under one,
1987 at Green Acres research


and energycane silages made
two, and three harvests in
farm near Gainesville, FL.


Total Flieg points
G eF-tes I Harvests in 1987
Genotype F-test 1 2 3


PI 300086 99a 93a 100a

Merkeron 99ab 97a 94ab

L79-1002t 94b 69b 76b



Mott L** Q** 100 70 63


tEnergycane (Saccharum spp.).


Means in the same column followed by the same
different at the 5% level according to DMRT.


letter are not


Linear (L) and/or quadratic (Q) effects are significant over harvest
treatments, P<0.01 (**) or P<0.05 (*).


Table 25.











treatment combinations ranged from 84 to 98% (Tables 26 and 27).

Although some linear effects did appear, it is still unclear how DM

recovery is affected by harvest frequency. It is interesting to note

that with an ensiling method similar to the one used in the present

study, Brown and Chavalimu (1985) reported a 96% DM recovery for

elephantgrass harvested at 5 weeks of age.


Utilization of Elephantgrass Silage


At this point it is reasonable to conclude that elephantgrass at

various stages of plant maturity can be successfully stored for

prolonged periods using the ensilage process. However, further

investigation is needed to determine the types of silages that can be

most efficiently transformed into commercial products such as meat,

milk, and biogas.

In ruminant nutrition, animal performance is a function of

voluntary intake and digestibility of the forage being fed (Moore and

Mott, 1973). In the present study, the ensiling of elephantgrass and

energycane did not result in major changes in the original IVOMDs

shown in Tables 5 and 6 of Chapter Two. The mean percentage point

differences during 1986-87 between IVOMDs before and after ensiling

(Silage IVOMD Original IVOMD = Difference) ranged from -9.4 to +4.2

(Table 28). The overall mean difference for all treatment

combinations during both years was -1.6. It should be noted that the

IVOMD values recorded for ensiled plant materials (not shown) may have

been slightly underestimated due to the losses of volatile substances

during the oven-drying of samples. The Moore and Mott (1974) IVOMD












Table 26.


Dry matter recovery of elephantgrass and energycane forages
that were stored by ensiling in 1986 at Green Acres
research farm near Gainesville, FL.


Dry matter recovery
Harvests in 1986
Genotype F-testl 1 2 3 Average



PI 300086 88 90 89 89a

Merkeron 91 89 87 89a

L79-10021 91 87 88 89a

Overall average 90 89 88

--------------------------------------------------------

Mott L** 94 87 86 89


tEnergycane (Saccharum spp.).


Means in the same column followed by the same
different at the 5% level according to DMRT.


letter are not


"Linear (L) and/or quadratic (Q) effects are significant over harvest
treatments, P<0.01 (**) or P<0.05 (*).











Table 27.


Dry matter recovery of elephantgrass and energycane forages
that were stored by ensiling in 1987 at Green Acres
research farm near Gainesville, FL.


Dry matter recovery
Harvests in 1987
Genotype F-test 1 2 3 Average



PI 300086 91 93 96 94a

Merkeron 92 92 93 92a

L79-1002t 84 89 92 89b

Overall average L** 89 91 94



Mott 98 92 94 95


tEnergycane (Saccharum spp.).


Means in the same column followed by the same
different at the 5% level according to DMRT.


letter are not


Linear (L) and/or quadratic (Q) effects are significant over harvest
treatments, P<0.01 (**) or P<0.05 (*).












Table 28.


Mean percentage point difference between in vitro organic
matter digestibilities before and after the ensiling of
elephantgrass and energycane which were gathered from plots
harvested one, two, and three times per year at the Green
Acres research farm near Gainesville, FL, during 1986-87.


IVOMD difference
Harvests yr-1

Genotype Year 1 2 3



PI 300086 1986 2.6 -1.6 -0.4

Merkeron 1986 -0.9 -3.2 -1.3

L79-10021 1986 0.5 -5.9* -1.9

Mott 1986 -0.4 -3.8* 1.3


PI 300086 1987 -4.6 -2.8 2.2**

Merkeron 1987 -4.3 -5.2 1.3*

L79-1002 1987 -9.4* -5.7* -1.5

Mott 1987 2.7* -0.2 4.2*


tEnergycane (Saccharum spp.).


Differences were computed as follows:
IVOMD = Difference.


Silage IVOMD Original


*,**Original forage and corresponding silage IVOMDs were significantly
different at the 5 and 1% levels, respectively, according to the
F-test.











procedure used for determinations involved 1050C oven-drying of

previously dried samples (at 600C) for 15 hours. Nevertheless, the

data clearly demonstrate that ensiling is not a major factor affecting

IVOMD. Therefore, the major factors affecting silage IVOMD would be

the same as those affecting the IVOMD of original biomass such as

harvest frequency and genotype. Working with sheep, Demarquilly

(1973) observed similar results. Mean percentage point differences in

apparent organic matter digestibility (corrected for volatile losses)

between initial forages of several plant species and their

corresponding silages ranged from -12.8 to +3.0. He concluded that

the digestibility of ensiled material is mainly dependent on that of

the original plant herbage at the time of harvest.

Many studies have shown the voluntary intake of silage to be

lower than that of the original forage prior to ensiling (Wilkinson et

al., 1976). The magnitudes of these reductions can be highly

variable. Working with sheep, Demarquilly (1973) reported reductions

in voluntary intake of silages that were made from several forage

species, ranging from one to 64% when compared to the intakes of the

original standing forages. The greater reductions in intake were

attributed to silages with higher levels of volatile fatty acids,

particularly acetic acid. The lesser reductions were related to

silages that contained mostly lactic acid as the end-product of

fermentation. Wilkins et al. (1971) also showed that the voluntary

intake of sheep was negatively correlated with acetic acid contents in

silages made from several forage species. Furthermore, their results

showed that silage Flieg scores and intake were positively correlated.











In the present study, the silages containing the higher levels of

acetic acid such as those made from immature Mott dwarf elephantgrass

are the most likely to have problems with reduced voluntary intake.

In the literature, daily voluntary intakes of elephantgrass

silage have been variable. In Cuba, Michelena et al. (1979) fed

elephantgrass silage ad libitum plus minerals over a 160- to 180-day

period to holstein x zebu bulls averaging 247 kg in liveweight. The

silage contained 26% DM and a crude protein content of 4.8% (dry

basis). Mean daily consumption of DM was 2.4% of liveweight. In

Brazil, Vilela et al. (1983) fed elephantgrass silage to holstein x

Zebu heifers averaging 258 kg in liveweight. The silage was made from

9- to 10-week old forage and contained 21% DM and 4.4% crude protein

(dry basis). Average daily consumption of DM was estimated to be 2.7%

of liveweight.

On the negative side, Cunha and Silva (1977) reported that

elephantgrass silage ensiledd with 3% molasses) fed alone during the

dry period in Brazil was inadequate for maintaining acceptable

production of cows just prior to and after calving. Silage

composition was 21% DM, 54% total digestible nutrients, and 8.1% crude

protein (dry basis). The ad libitum feeding of the silage plus salt

and minerals resulted in excessive postpartum weight loss of the cows,

poor calf development, and a reduced rebreeding percentage when

compared to a pasture feeding system. The poor performance was

attributed to inadequate daily DM consumption. The average daily

intake of DM was only 5.8 kg. The mean initial weight of the cows was

507 kg. In India, Nooruddiu and Roy (1975) fed elephantgrass silage











ad libitum plus salt to mature steers averaging 237 kg in liveweight.

The estimated contents of crude protein and total digestible nutrients

in the silage were 5.1 and 46% (dry basis), respectively. Mean daily

DM intake over an 18-day period was 1.3% of liveweight.

In a methane production system, the loading rate of biomass is

not under the voluntary control of anaerobic digesters. It can be

controlled and adjusted by the operator to optimize conversion rates

depending on the given circumstances. Therefore, loading rate should

not be a potential limiting factor as voluntary intake is in livestock

feeding systems. Furthermore, high levels of acetic acid in silage

which limits voluntary intake in ruminants, should not be a problem in

anaerobic methane digestion, since it is a major substrate used by

methanogenic bacteria (Gottschalk, 1979). However, if acetic acid is

the major end-product of the ensilage process, the quality of

preservation could be reduced because it is a weaker acid compared to

lactic acid. This would increase the chances of substantial DM losses

during a prolonged storage period.

The DM losses that occur during normal ensiling fermentations may

not greatly reduce the potential methane production per unit of land

area that is expected from a system where the biomass after harvesting

is immediately placed in a methane digester. The gross energy content

is as much as 10% greater per unit dry matter in silage than in the

initial biomass before ensiling (Woolford, 1984). In the present

study, methane yields per kg of volatile solid from a limited number

of samples, have been higher for elephantgrass silage than those of

original fresh biomass. Average methane yields for fresh PI 300096











elephantgrass gathered during the first cutting within the three

harvest yr-1 treatment during 1986 and 1987 were 0.28 and 0.29 std m3

kg-l VS, respectively. Average yields from the corresponding silages

were 0.33 and 0.33 std m3, respectively. The methane yields of silage

samples may, however, be inflated due to problems associated with the

estimation of DM content of silage. At the Bioprocess Engineering

Research Laboratory where the bioassays were conducted, an 1050C oven

temperature was used for drying silage samples. At that temperature

significant losses of volatile substances may have occurred during

drying. Further detailed investigations are needed to determine if

ensiling biomass improves methane yield.


Conclusions


Elephantgrass and energycane grown under one, two, and three

harvests per season can be successfully stored for prolonged periods

through the process of ensilage fermentation and without the use of

additives. The success of ensiling these erect bunchgrasses in the

present study is associated with a combination of desirable

characteristics of the original fresh biomass. The fresh chopped

plant materials apparently contained adequate levels of water soluble

carbohydrates that provided energy for fermentation bacteria to

proliferate. In addition, the initial forages possessed low buffering

capacities (low rLsistances to pH changes). This combination of

attributes of the freshly harvested herbage helps to explain the ease

with which these grasses were ensiled.











Lactic acid was the primary end-product of fermentation in

silages made from the tall elephantgrass genotypes PI 300086 and

Merkeron under all harvest frequencies and from the full-season growth

of L79-1002 energycane and Mott dwarf elephantgrass. However, with

silages made from immature plants of L79-1002 and Mott, analysis

showed that lactic and acetic acids were both major end-components of

silage fermentation. The elevated acetic acid levels in Mott silages

may negatively affect voluntary intake of ruminants. In a methane

energy production system acetic acid being a major end-product of

fermentation, should not affect methane yields per volatile solid of

silage, but could reduce the preservation quality of the biomass,

leading to greater chances of losing substantial amounts of DM during

a prolonged storage period.

From a strict quantitative standpoint, the forages produced

during the present study were effectively stored using the ensilage

process. However, further investigations are needed to determine from

an ultimate production standpoint, whether elephantgrass and

energycane can be stored as silage and then efficiently converted into

meat, milk, or energy products.















CHAPTER 4
GENERAL SUMMARY AND CONCLUSIONS


Elephantgrass is a perennial erect-growing bunchgrass indigenous

to the wet equatorial areas in Africa. Recently, interests in this

plant species have increased in several agricultural disciplines.

Highly productive "tall" genotypes can be utilized as a biomass crop

for energy or a soilage crop for ruminants such as dairy and beef

cattle. For grazing animals, "dwarf" genotypes have been shown to be

of high forage quality and are persistent under moderate grazing

conditions.

In a 2-year study conducted on a dry, infertile site and under

the subtropical conditions near Gainesville, the response of

elephantgrass to three harvest frequencies was measured. Genotypes

evaluated were four "tall" elephantgrasses (PI 300086, Merkeron, N-43,

and N-51), a "dwarf" elephantgrass ('Mott'), a "semi-dwarf" Pennisetum

glaucum (L.) R. Br. x P. purpureum Schum. hybrid (Selection No. 3) and

a "tall" Saccharum species of energycane (L79-1002). To determine if

these grasses could be stored as silage, the fresh chopped plant

materials of PI 300086, Merkeron, Mott, and L79-1002 were hand-packed

into 20-liter plastic containers lined with two 4-mil plastic bags.

Average dry biomass yields for the four tall elephantgrasses
-1 -1
during the 1986-87 growing seasons were 27, 24, and 18 Mg ha yr

for one, two, and three harvests per season, respectively. In vitro

organic matter digestibilities were 40, 49, and 55%, while crude











protein contents were 4.0, 5.8, and 7.9% (dry basis), respectively.

Two-year averages for ash-free neutral detergent fiber were 81, 76,

and 74% (dry basis).

Oven dry biomass yields for L79-1002 energycane were inferior to

the tall elephantgrasses during 1986 but did not differ the following

season. Energycane yields declined with more frequent harvesting.

For the dwarf elephantgrass Mott, 2-year average dry biomass

yields were 13, 12, and 11 Mg ha~1 yrI for one, two, and three

harvests per season, respectively. In vitro organic matter

digestibilities were 40, 54, and 57%, while crude protein contents

were 5.3, 7.1, and 9.6%, respectively. Two-year means for neutral

detergent fiber were 77, 73, and 70%.

Elephantgrass genotypes Merkeron, N-43, N-51, and Mott and

L79-1002 energycane survived the experimental conditions. The

genotype PI 300086 was susceptible to winterkill, particularly when

harvested multiple times per season. An almost complete loss of stand

occurred in Selection No. 3 plots during the 2-year study.

Predicted methane production ha-1 for PI 300086 elephantgrass was

similar for the three harvest treatments, although the highest values

were recorded from two harvests per season.

Mean pH values ranged from 3.8 to 4.0 for the tall elephantgrass

silages made from plants harvested at the different frequencies. The

highest pH values were obtained from silages made from immature Mott

plants harvested three times yr-1 (2-year mean was 4.3). Water

soluble carbohydrate contents of fresh elephantgrass forages (range:

2.6 to 8.4%, dry basis) tended to increase with more frequent











harvesting. Buffering capacities of fresh PI 300086 and L79-1002

biomass were exceptionally low and also increased with more frequent

harvesting. Mean buffering capacities were less than 150 meq NaOH

kg-1 DM. Dry matter contents of fresh biomass decreased with more

frequent harvesting for all genotypes during both growing seasons.

Lactic acid was the major end-product of fermentation in most silages

with the exception of those made from immature Mott elephantgrass and

L79-1002 energycane plants where lactic and acetic acids were both

major components. Average lactic acid contents during both seasons

ranged from 1.4 to 5.3% (dry basis) for the elephantgrasses whereas

mean acetic acid levels ranged from 0.25 to 2.21% (dry basis). Acetic

acid contents in silages tended to increase when original plant

materials before ensiling were more immature and succulent as compared

to more mature materials. Butyric acid levels were negligible in all

silages. Mean ammoniacal N percentages of total N in PI 300086 and

L79-1002 silages ranged from 7.7 to 11.0. Dry matter recoveries for

all silages ranged from 84 to 98%. The in vitro organic matter

digestibility of silage was mainly dependent on the IVOMD of the

standing forages before ensiling.

The results of this study suggest the following general

conclusions:

(1) Substantial biomass yields of elephantgrass can be produced

without irrigation on dry, infertile sites and under the colder

subtropical climate of North Central Florida.

(2) For the four tall elephantgrasses and L79-1002 energycane,

as the number of harvests per growing season increases, the dry












biomass yields decline. With Mott dwarf elephantgrass, biomass yields

are less affected by the harvest frequencies included in this study.

(3) For tall and dwarf elephantgrasses, forage crude protein

contents and IVOMDs increase as the number of harvests per growing

season increases. Neutral detergent fiber concentrations gradually

decrease; however, major reductions do not occur.

(4) Variation in survival tolerance to increased harvest

frequency and the subtropical conditions near Gainesville exists among

genotypes. Elephantgrass genotypes Merkeron, N-43, N-51, and Mott and

L79-1002 energycane could be recommended for planting in the area

while PI 300086 and Selection No. 3 are not suitable.

(5) Elephantgrass and energycane grown under one, two, and three

harvests per growing season can be successfully stored for prolonged

periods through the ensiling process and without the use of additives.

(6) The ease with which the elephantgrasses and energycane were

ensiled can be attributed to adequate levels of water soluble

carbohydrates and the inherently low buffering capacities in the

standing forages at the time of harvest.

The data show that many of the forages and silages produced in

this study are potential sources of feedstocks that could be converted

into animal and energy products. However, before other definite

conclusions can be made, further investigations involving the actual

components of conversion systems are needed (i.e., involving animals

and anaerobic digesters). If problems do exist in a system such as

inadequate animal intake or insufficient net energy production, for

example, then it is likely they can be identified.



































APPENDIX











Table 29. Oven dry biomass yield of elephantgrass genotypes from
single harvests within multiple harvest treatments made
during 1986 at Green Acres research farm near Gainesville,
FL.


Oven dry biomass yield

Harvests in 19865

2 3
Genotype 1st 2nd 1st 2nd 3rd

Mg ha -1

PI 300086 15.51 14.21 7.19 8.25 6.32

Merkeron 15.57 12.10 7.68 8.51 5.19

N-43 15.27 12.05 6.64 7.90 4.62

N-51 15.51 12.04 5.67 7.30 5.01

L79-1002t 9.06 9.61 3.71 6.90 3.70

Selection No. 3t 9.02 8.67 3.91 5.54 2.46

Mott 8.20 6.56 3.96 5.14 2.66


Energycane (Saccharum spp.).

tPearlmillet x elephantgrass hybrid.

For oven dry biomass yield of full-season growth refer to Table 1.












Table 30.


Oven dry biomass yield of elephantgrass genotypes from
single harvests within multiple harvest treatments made
during 1987 at Green Acres research farm near Gainesville,
FL.


Oven dry biomass yield

Harvests in 1987

2 3
Genotype 1st 2nd 1st 2nd 3rd

Mg ha -1

PI 300086 12.34 7.93 4.80 5.55 2.54

Merkeron 12.51 8.26 6.74 7.32 2.10

N-43 12.48 8.10 6.34 6.61 1.98

N-51 11.64 6.46 6.49 7.29 2.34

L79-1002t 9.37 8.50 4.16 7.07 2.44

Selection No. 3* 2.93 1.14 3.40 2.63 0.19

Mott 5.83 3.39 4.51 4.46 0.79


tEnergycane (Saccharum spp.).

tPearlmillet x elephantgrass hybrid.

For oven dry biomass yield of full-season growth refer to Table 2.











Table 31.


Crude protein content of elephantgrass genotypes from
single harvests within multiple harvest treatments made
during 1986 at Green Acres research farm near Gainesville,
FL.


Crude protein

Harvests in 19865

2 3
Genotype 1st 2nd 1st 2nd 3rd

%, dry basis

PI 300086 6.02 5.20 6.87 9.39 7.46

Merkeron 5.98 4.70 6.86 9.25 8.08

N-43 8.18 5.59 7.23 9.18 7.37

N-51 5.44 5.11 7.29 9.31 8.03

L79-1002t 5.93 5.11 8.05 8.40 7.06

Selection No. 3t 8.42 6.49 7.30 11.13 10.62

Mott 7.53 6.17 7.36 10.21 8.74


tEnergycane (Saccharum spp.).

Pearlmillet x elephantgrass hybrid.

For crude protein content of full-season growth refer to Table 3.











Table 32.


Crude protein content of elephantgrass genotypes from
single harvests within multiple harvest treatments made
during 1987 at Green Acres research farm near Gainesville,
FL.


Crude protein

Harvests in 19875

2 3
Genotype 1st 2nd 1st 2nd 3rd

%, dry basis

PI 300086 5.66 6.52 5.79 6.40 10.37

Merkeron 5.62 6.20 5.94 6.25 10.39

N-43 4.84 6.26 7.06 6.78 11.27

N-51 4.94 6.34 6.35 6.61 10.27

L79-1002t 5.29 6.03 7.05 5.67 9.24

Selection No. 34 7.65 -- 9.96 9.36

Mott 6.09 8.54 7.37 7.59 16.31


tEnergycane (Saccharum spp.).

*Pearlmillet x elephantgrass hybrid.

For crude protein content of full-season growth refer to Table 4.











Table 33. In vitro organic matter digestibility (IVOMD) of
elephantgrass genotypes from single harvests within
multiple harvest treatments made during 1986 at Green Acres
research farm near Gainesville, FL.


IVOMD

Harvests in 19865

2 3
Genotype 1st 2nd 1st 2nd 3rd



PI 300086 46.2 48.2 55.6 55.5 53.8

Merkeron 48.5 49.6 58.5 56.9 51.7

N-43 52.5 50.9 58.8 57.2 52.7

N-51 49.4 48.9 57.7 56.1 54.1

L79-1002t 47.5 47.4 51.1 50.7 48.7

Selection No. 3t 57.4 54.3 61.2 59.9 48.2

Mott 55.4 54.1 61.6 59.9 51.3


tEnergycane (Saccharum spp.).

*Pearlmillet x elephantgrass hybrid.

For IVOMD of full-season growth refer


to Table 5.











Table 34.


In vitro organic matter digestibility (IVOMD) of
elephantgrass genotypes from single harvests within
multiple harvest treatments made during 1987 at Green Acres
research farm near Gainesville, FL.


IVOMD

Harvests in 1987

2 3
Genotype 1st 2nd 1st 2nd 3rd



PI 300086 50.8 43.6 58.1 49.5 54.0

Merkeron 53.7 46.8 59.6 53.1 50.9

N-43 51.3 46.3 59.7 54.1 52.3

N-51 51.2 42.9 59.5 52.8 52.5

L79-1002t 47.8 46.9 52.2 45.2 53.1

Selection No. 3t 57.2 -- 60.0 54.3

Mott 59.3 47.4 58.3 57.8 51.4


tEnergycane (Saccharum spp.).

Pearlmillet x elephantgrass hybrid.

For IVOMD of full-season growth refer to Table 6.











Table 35.


Ash-free neutral detergent fiber (NDF) content of
elephantgrass genotypes from single harvests within
multiple harvest treatments made during 1986 at Green Acres
research farm near Gainesville, FL.


NDF

Harvests in 19865

2 3
Genotype 1st 2nd 1st 2nd 3rd

%, dry basis

PI 300086 80.6 75.1 77.3 75.0 74.7

Merkeron 76.4 75.7 73.8 73.9 71.6

N-43 75.5 74.5 75.2 72.9 73.0

N-51 77.7 76.5 75.3 73.2 72.3

L79-1002t 78.0 77.5 76.0 77.2 77.9

Selection No. 3* 71.3 72.7 68.6 68.0 67.4

Mott 73.0 73.4 69.8 71.0 68.5


tEnergycane (Saccharum spp.).

tPearlmillet x elephantgrass hybrid.

For NDF content of full-season growth refer to Table 7.











Table 36.


Ash-free neutral detergent fiber (NDF) content of
elephantgrass genotypes from single harvests within
multiple harvest treatments made during 1987 at Green Acres
research farm near Gainesville, FL.


NDF

Harvests in 19875

2 3
Genotype 1st 2nd 1st 2nd 3rd

%, dry basis

PI 300086 76.5 78.5 74.9 80.4 73.6

Merkeron 74.8 76.1 73.6 77.4 73.5

N-43 76.2 74.8 72.0 77.0 73.2

N-51 76.7 78.0 73.1 77.1 72.2

L79-1002t 76.8 75.4 77.3 81.6 75.5

Selection No. 3t 67.7 -- 66.4 71.6

Mott 69.9 74.7 69.3 73.8 65.6


Energycane (Saccharum spp.).

tPearlmillet x elephantgrass hybrid.

For NDF content of full-season growth refer to Table 8.











Table 37.


Dry matter content of elephantgrass and energycane from
single harvests within multiple harvest treatments made
during 1986 at Green Acres research farm near Gainesville,
FL.


Dry matter

Harvests in 19865

2 3
Genotype 1st 2nd 1st 2nd 3rd



PI 300086 22.7 29.5 17.5 18.8 20.6

Merkeron 21.3 29.5 16.5 19.0 24.6

L79-1002t 22.0 26.6 18.4 21.6 23.1

Mott 21.2 25.4 20.3 18.5 22.9


tEnergycane (Saccharum spp.).

"For dry matter content of full-season growth refer to Table 11.











Table 38.


Dry matter content of elephantgrass and energycane from
single harvests within multiple harvest treatments made
during 1987 at Green Acres research farm near Gainesville,
FL.


Dry matter

Harvests in 1987

2 3
Genotype 1st 2nd 1st 2nd 3rd



PI 300086 25.3 27.4 18.9 20.5 19.4

Merkeron 23.0 26.9 17.3 19.5 24.0

L79-1002t 21.8 28.3 20.3 20.2 26.3

Mott 20.0 28.0 19.1 20.0 35.4


tEnergycane (Saccharum spp.).

For dry matter content of full-season growth refer to Table 12.











Table 39.


Water soluble carbohydrate (WSCHO) content of elephantgrass
and energycane from single harvests within multiple harvest
treatments made during 1987 at Green Acres research farm
near Gainesville, FL.


WSCHO

Harvests in 19875

2 3
Genotype 1st 2nd 1st 2nd 3rd

%, dry basis

PI 300086 10.64 6.09 10.43 10.88 3.16

Merkeron 9.12 5.98 10.28 10.38 2.92

L79-1002t 12.04 7.06 8.52 8.73 4.18

Mott 7.17 1.97 7.79 6.13


tEnergycane (Saccharum spp.).

For WSCHO content of full-season growth refer to Table 13.











Table 40.


Buffering capacity of PI 300086 elephantgrass and L79-1002
energycane from single harvests within multiple harvest
treatments made during 1987 at Green Acres research farm
near Gainesville, FL.


Buffering capacity

Harvests in 19875

2 3
Genotype 1st 2nd 1st 2nd 3rd

-Meq NaOH kg-1 DMt

PI 300086 76.2 78.9 99.8 81.3 156.2

L79-1002 148.7 112.7 175.3 130.0 131.9


Milliequivalents of NaOH required to raise the pH of one kg of
biomass DM from 4.0 to 6.0.

For buffering capacity of full-season growth refer to Table 14.











Table 41.


The pH of elephantgrass and energycane silages made with
plants from single harvests within multiple harvest
treatments during 1986 at Green Acres research farm near
Gainesville, FL.


Silage pH

Harvests in 19865

2 3
Genotype 1st 2nd 1st 2nd 3rd


PI 300086 3.91 3.81 3.92 4.03 3.92

Merkeron 3.91 3.86 3.97 4.02 4.14

L79-1002t 3.97 3.88 4.10 4.39 4.33

Mott 4.21 4.08 4.05 4.50 4.26


Energycane (Saccharum spp.).

-For pH of silages made from full-season growth refer to Table 15.











Table 42.


The pH of elephantgrass and energycane silages made with
plants from single harvests within multiple harvest
treatments during 1987 at Green Acres research farm near
Gainesville, FL.


Silage pH

Harvests in 19875

2 3
Genotype 1st 2nd 1st 2nd 3rd


PI 300086 3.80 3.76 3.89 3.76 3.89

Merkeron 3.81 3.71 3.88 3.79 3.94

L79-1002t 4.17 3.83 4.11 4.06 3.95

Mott 4.23 4.27 4.33 4.42 --


tEnergycane (Saccharum spp.).

For pH of silages made from full-season growth refer to Table 16.











Table 43.


Lactic acid content of elephantgrass and energycane silages
made with plants from single harvests within multiple
harvest treatments during 1986 at Green Acres research farm
near Gainesville, FL.


Lactic acid

Harvests in 19865

2 3
Genotype 1st 2nd 1st 2nd 3rd

%, dry basis

PI 300086 3.07 3.00 3.58 3.83 3.50

Merkeron 3.40 3.45 2.14 4.79 3.76

L79-1002t 2.30 3.30 1.07 0.03 0.89

Mott 2.74 3.93 2.63 0.33 4.23


tEnergycane (Saccharum spp.).

For lactic acid content of silages made from full-season growth refer
to Table 17.