PRQ UCTIO R'OLUNTARY CONSUMPTION,
AN ~iSTIBILITY OF FORAGES
WHEN USED AS FEEDS
FOR DAIRY CATTLE IN FLORIDA
J. M. Wing
BULLETIN 688 (technical) JANUARY 1965
Agricultural Experiment Stations
University of Florida, Gainesville
J. R. Beckenbach, Director
Methods and Materials 4
Results .. 5
Discussion .. .. 5
Conclusions and Recommendations .. 13
Literature Cited .. ... .... 13
Production, Voluntary Consumption, And
Digestibility Of Forages When Used As
Feeds For Dairy Cattle In Florida
J-. Win. I
The pressures of modern civilization heighten the need for
efficiency in all phases of livestock production. Population pres-
sures are increasing the over-all demand for food. The genetic
merit of dairy cattle has improved considerably, and further
advancements in animal quality are imminent. Increasing costs
of labor and general expense make it necessary for all the here-
ditary efficacy of cattle to be utilized. This makes it mandatory
to feed dairy cattle to their capacity for production.
Increased production of human food by dairy cattle and other
livestock may result from the development of higher producing
feed crops and from more efficient utilization and conversion
of the feed. It appears that the first provision is being met.
Various experiments with dairy cattle have shown that im-
proved forages produced as much as 10 times the nutrients
which were derived from native pastures (3, 6, 7, 8, 9, 10,).2
Further enrichment of forage productivity and quality through
plant breeding and soil science research is in progress.
Even now it appears that forage nutrients are available at
a fraction of the cost of the same constituents in concentrate
feeds (12). Yet few Florida dairymen make full use of green
feeds either as pasture or as greenchop. A recent economic survey
indicated that many dairies which operated mainly or entirely
on purchased feeds were more profitable than comparable opera-
tions which utilized green forages extensively (1). Since pre-
vious evaluations of forages have involved mainly a quantitative
appraisal of yield, and qualitative features have been almost
completely ignored, forages even on progressive dairy farms
might not have been used as efficiently as possible. Thus, a
better selection of supplements for use with green forage is
The purpose of the work presented herein was to determine
the amount of forage which is likely to be consumed daily by
1Associate Dairy Husbandman.
Numbers in parentheses refer to Literature Cited.
Florida Agricultural Experiment Stations
dairy cattle which have free access to it and the extent to which
the nutrients contained therein are digested. Using such data,
it should be possible to formulate the most effective supplements
possible under given conditions.
Production methods and costs will vary, of course, and so
will the yields. Records were kept, however, of the requirements
for materials and labor in addition to such other pertinent in-
formation as might be used in connection with prevailing costs
as a guide in determining the feasibility of using greenchop.
MATERIALS AND METHODS
Included in the study were various forages which are likely
to be used as either pastures or greenchop in Florida. Improved
varieties (Table 1) were managed over three growing seasons
according to procedures which were recommended for each crop
pursuant to annual soil tests. All forages were cut into self-
unloading wagons, weighed, and fed to mature, healthy steers,
dry cows, or large heifers. Refusal likewise was weighed and
analyzed. Consumption rates then were computed on the basis
of 1,000 pounds of body weight. Most of the animals used for
this study weighed close to 1,000 pounds, and adjustments for
body surfaces, made as suggested by Brody (4), were slight.
Adjustments were made in this manner because consumption
of feed is more likely to vary according to surface rather than
directly with weight.
Lactating cows doubtless consume slightly different amounts
of forage than experimental animals used herein because they
also receive large amounts of concentrate feeds. Since their
nutrient requirements also are higher, however, this would not
seem to cause an appreciable error. The digestibility determina-
tions were made by indicator methods, employing either chrom-
ium oxide or indigestible plant chromogens according to pro-
cedures approved by the American Society of Agronomy, Ameri-
can Dairy Science Association, American Society of Animal
Production, and the American Society of Range Management
(11). The feeds and feces were assayed for dry matter, protein,
and organic matter; and the feeds for ether extract by standard
methods (2). The techniques of Lofgren and Meyer (5) were
used to determine the total digestible nutrients (TDN) of the
feeds. Separate determinations were made for digestibility of
dry matter and digestible crude protein (DCP).
F.r ., -. for Dairy Cattle in Florida
All forages were planted in measured plots (usually 2 acres).
Costs will vary considerably, and hence production requirements
were ascertained in terms of material and labor. The distance
from the point of feeding was measured by a truck odometer
which had been calibrated by driving over a measured distance.
It should be noted that the plots were small and relatively small
loads were cut. Thus less labor is likely to be required in com-
Production requirements and yields, along with other per-
tinent data, have been summarized in Tables 2 and 3. Nine crops
and combinations of crops are included.
Five grass-type forages, two legumes, one legume mixture,
and three grass-legume mixtures were investigated by means
of feeding and digestibility experiments. Rates of consumption
and digestibility have been summarized in Table 4. Two addi-
tional forages for which production data are not available have
been included also. They are presented on both the dry and
fresh basis. When used in connection with feeding standards,
this information is designed to facilitate the formulation and
feeding of rations to various classes of cattle. Since the amount
of TDN and DCP which might be expected from forages of the
types investigated herein can be determined from the table,
the quality and the amount of supplementary feeds can be de-
termined without difficulty. Of course, individual animal varia-
tions will make adjustments necessary. Moreover, fertilization
and stage of maturity of the plants at harvest are related to
protein and the TDN content.
All forages included in this study were raised according to
recommended practices and utilized at what appeared to be the
most nutritious stage (usually prebloom) within the limitations
imposed by normal management details. Under these conditions
little variation occurred among years or cuttings as shown by
the small standard deviations in Tables 3 and 4. Therefore, all
data were combined to show the value of greenchop under re-
Exact data are presented in the tables. The discussion there-
fore is of a general interpretive nature.
S-1 strain of
Dixie 18 green
plus S-1 strain of
S-1 strain of
* Two tons per acre of finely
ble 1.-Annual production data per acre for nine forages and combinations.
Soil Type Seed Fertilizer*
(amount) Analysis Amount, lb./yr.
Scranton 14 lb. 2-10-20 650
fine sand 60, muriate of potash 250
Orlando 14 lb. alfalfa 2-10-20 1000
fine sand 3 Ib. clover
Period of Harvest
Mar. 5-June 30
Feb. 19-June 23
Orlando 2 bu. 8-8-8 600 May 5-May 15
fine sand Anhydrous ammonia 82
Leon 5-1/3 bu. 5-10-15 1000 Nov. 15-Apr. 14
fine sand Ammonium nitrate 225
Leon 5 bu. oats 5-10-15 1000 Nov. 15-Apr. 20
fine sand 13.5 lb. alfalfa 2-10-20 1000
Frit FTE 502 60
Leon 5 bu. oats 5-10-15 1000 Dec. 1-May 1
fine sand 3 lb. clover 2-10-20 1000
Frit FTE 502 60
Orlando 5 Ib. 8-8-8 500 May 20-Sept. 30
fine sand Ammonium nitrate 300
Orlando 22.5 lb. 5-10-15 500 June 10-June 20
fine sand Ammonium nitrate 200
Scranton 3 lb. 2-10-20 600 Feb. 1-June 30
fine sand 60; miuriate of potash 175
ground calcic limestone were applied before this experiment began, and annual soil tests did not show a need for further
Table 2.-Labor requirements and harvesting data.
Labor Requirements, man-hours per acre
Alfalfa plus clover
Oats plus alfalfa
Oats plus clover
No. of Hauled
3.83 also was involved in cultivating iearlmillet.
8 Florida Agricultural Experiment Stations
Alfalfa.-Eighty-eight consumption and digestion trials were
completed with alfalfa. Ninety-nine pounds per 1,000 pounds of
body weight daily were consumed; this supplied 12.1 pounds of
TDN, sufficient for maintenance and the production of about
16 pounds of 4 percent fat corrected milk (FCM), and 2.3 pounds
of protein, which is enough for body maintenance and produc-
tion of about 24 pounds of 4 per cent FCM. A high energy,
medium protein feed would be adequate for supplementing
greenchop alfalfa. Table 3 shows alfalfa to be a very productive
forage. Production requirements are moderate, but it must
be managed carefully.
Table 3.-Annual yields per acre of various forages.
Forage Cuttings Greenchop TDN* DCP**
(number) (tons) (lb.) (lb.)
Alfalfa 5 32.10 7768 1477
Alfalfa plus clover 4 24.20 4743 1.500
Green corn 1 10.00 1940 180
Oats 4 10.00 1780 300
Oats plus alfalfa 5 16.00 3424 672
Oats plus clover 4 12.00 2616 456
Pearlmillet 5 34.25 8220 1233
Sart Sargo 1 22.00 2860 308
White clover 4 11.25 2903 788
Total digestible nutrients.
Digestible crude protein.
Alfalfa Plus Clover.-Fourteen determinations were made
with this legume combination. The forage was very palatable,
and 119 pounds per 1,000 pounds of body weight were consumed
daily. This supplied 16.6 pounds of dry matter, 9.8 pounds of
TDN (sufficient for maintenance and production of slightly less
than 9 pounds of 4 percent FCM), and 3.1 pounds of protein,
enough for maintenance and almost 36 pounds of 4 percent FCM.
In this case the main limiting factor to be considered in supple-
mentary feeds is the energy-bearing nutrients. This combina-
Forages for Dairy Cattle in Florida
tion was very productive of digestible protein and excellent as
a supply of TDN. Production requirements were moderate, but
the sward had to be reseeded each season.
Green Corn.-Twenty-one trials were completed with green
corn as the experimental feed. An average of 102 pounds per
1,000 pounds body weight was consumed daily. This supplied
15.8 pounds of dry matter, 9.7 pounds of TDN, and 0.9 pounds
of DCP. Supplementary feeds to green corn therefore should
be high in both energy-bearing nutrients and DCP. Green corn
supplies nutrients for a relatively short period, since regrowth
of this crop is not satisfactory. Production requirements are
moderate, and this forage may be used as a complement to other
roughages where needed.
Oats.-Eighty-five digestion and consumption trials were
completed on this forage (Table 4). The data exhibited in Tables
1 to 3 indicate moderate expense and a reasonable yield. On a
per acre basis, the yield of TDN and DCP was 1780 and 300
pounds, respectively (Table 3). An average of 80 pounds of
forage containing 14.2 pounds of dry matter, 8.9 pounds of TDN,
and 1.5 pounds of DCP was consumed per 1,000 pounds of body
weight daily. The TDN contained therein was sufficient for about
9 pounds of 4 percent FCM in addition to maintenance require-
ments. The protein consumption above maintenance require-
ments was sufficient for production of approximately 13 pounds
of 4 percent FCM. This is a very good roughage feed for dairy
cattle, but efficient use of oat forage for high producing cows
would depend upon additional feed which is very high in TDN
and DCP. Four cuttings were obtained under conditions of this
experiment. Tables 1 to 3 show both the nutrient yield and
requirements for production to be reasonable, particularly when
one considers the dates of production, since this crop supplies
green forage during the winter.
Oats Plus Clover.-Twenty-three digestion and consumption
trials were completed on the combination sward of oats and
clover. Per 1,000 pounds of body weight the daily consumption
was 109 pounds of forage which provided 18.2 pounds of dry
matter, 10.9 pounds TDN, and 1.9 pounds of DCP. Above main-
tenance requirement, the TDN was sufficient for production
of about 11.8 pounds of 4 percent FCM. The protein consumption
beyond maintenance requirements was sufficient for production
of approximately 18.6 pounds of 4 percent FCM. Thus, adequate
Table 4.-Daily consumption and digestibility of 11 forages by dairy cattle.
K Digesti- TDN Protein Intake/1000 Ib. body weight
No. of K Dry ability of % Dry Cc Fresh K, Dry Fresh Green- Dry
Animals Matter Dry Matter basis basis basis basis chop Matter TDN
88 19.9 62.1 61.0 12.2 11.3 2.3 99 19.7 12.1
2.21* 2.09 .43 .54 .12
plus clover 14 14.0 61.0 58.9 8.3 18.6 2.6 119 16.6 9.8
1.35 1.67 .21 .42 .06
rn 21 15.4 61.8 60.9 9.4 6.1 0.9 103 15.8 9.7
4.11 3.82 .89 .21 .05
85 17.8 64.5 63.1 11.2 10.8 1.9 80 14.2 8.9
2.11 2.88 .58 .55 .10
s alfalfa 38 17.2 63.6 62.6 10.8 12.0 2.1 99 17.0 10.7
.98 .28 .64 .12 .03
s clover 23 16.6 61.4 60.5 10.0 10.3 1.7 109 18.2 10.9
2.14 2.08 .46 .46 .06
s alfalfa 4 13.0 66.5 61.0 8.1 14.9 1.9 134 17.5 10.9
lover 1.23 3.16 .50 .28 .03
grass 8 18.7 66.2 68.0 12.7 8.5 1.6 74 13.8 9.4
1.36 1.51 .29 .22 .07
let 60 15.6 61.9 61.6 9.6 8.7 1.4 125 19.5 12.0
3.92 3.59 .65 .72 .11
go 8 19.0 57.2 56.9 10.8 5.0 1.0 60 11.4 6.5
4.22 3.72 .71 .17 .05
over 52 16.8 68.3 65.1 11.0 17.9 3.0 118 19.8 12.9
2.17 2.78 .53 .62 .11
: Figures in second line represent standard deviations.
Forages for Dairy Cattle in Florida
amounts of concentrate feeds which are high in energy and
moderately high in protein content are recommended for sup-
plementing this type of forage. Addition of clover to the oats
sward resulted in significant increases in the yield of both
TDN and DCP as shown in Table 2. The requirements for pro-
ducing the crop increased moderately.
Oats Plus Alfalfa.-Thirty-eight digestion and consumption
trials were completed on this forage. The total amount of feed
consumed averaged 99 pounds per 1,000 pounds of body weight
daily. This amount supplied 17 pounds of dry matter, 10.7
pounds of TDN, and 2.1 pounds of DCP. The TDN was sufficient
for maintenance and production of about 11.6 pounds of 4 per-
cent FCM. The digestible crude protein was sufficient for main-
tenance and the production of 21.0 pounds of 4 percent FCM.
Thus it seems likely that a concentrate mixture which is medium
in protein content would be sufficient for supplementing this
forage. Since the energy content is relatively low, the supple-
mentary feed should be high in energy-producing nutrients.
Alfalfa appeared to enhance the yield of oats considerably, as
well as supplying a large quantity of additional feed. Require-
ments for production changed mainly with respect to nutrient
requirements of the sward.
Oats Plus Alfalfa Plus Clover.-Data in this case are some-
what limited, since only four animal trials were completed. It
appears, however, that this is a very favorable combination,
since an average of 134 pounds of forage per 1,000 pounds of
body weight daily were consumed. It supplied an energy intake
comparable to those combinations already described (10.9
pounds) and sufficient protein beyond the maintenance require-
ments for the production of approximately 28.6 pounds of 4
percent FCM. Thus a concentrate mixture which is moderate
in protein content but high in energy-bearing nutrients would
seem to be appropriate for supplementing this mixture. The
stand was damaged by adverse weather conditions following
one cutting. Thus accurate production and yield data were not
Pangolagrass.-Eight trials were completed with pangola-
grass. This forage was in the prebloom stage, green, and heavily
fertilized. Unfavorable weather conditions followed this experi-
ment, however, and thus only one feeding period with eight
animals was completed. Under favorable conditions, several
Florida Agricultural Experiment Stations
cuttings of pangola per season are possible. Under conditions of
this experiment, animals consumed an average of 74 pounds of
pangolagrass per 1,000 pounds of body weight daily. This pro-
vided 13.8 pounds of dry matter, 9.4 pounds of TDN, and 1.2
pounds of DCP. Pangolagrass should be supplemented with
concentrate feeds which are high in both energy-bearing nutri-
ents and DCP for best results. Pangola is a persistent forage
where it is adapted, but unfavorable weather damaged the ex-
perimental stand, making accurate determinations of produc-
tivity and requirements impossible under conditions of this
Pearlmillet.-Sixty animal digestion and consumption trials
were completed with this forage. Per 1,000 pounds body weight,
the animals consumed an average of 125 pounds of herbage
daily. This supplied 19.5 pounds of dry matter containing 12.0
pounds of TDN and 1.8 pounds of DCP. The limiting factor is
mainly but not entirely energy, since the amount of protein
supplied by the forage above maintenance is enough for the
production of only 17 pounds of 4 percent FCM. Thus care should
be taken to supply supplementary protein as well as energy to
cows consuming mainly pearlmillet. This forage is one of the
most productive available. It grows well during the spring and
summer, supplying high quality feed when permanent grasses
are likely to be fibrous and lower in nutrients. Careful attention
is necessary, but production requirements are reasonable.
Sart Sargo.-Eight animal digestion trials were completed
with Sart Sargo. Sixty pounds of forage, 11.4 pounds of dry
matter, 6.5 pounds of TDN, and 0.7 pounds of DCP were con-
sumed daily. Supplementary feeds for Sart Sargo must be very
high in DCP, and rather large amounts must be consumed to
supply energy needed to supplement this type of forage. Sart
Sargo, like corn, is a single-harvest crop. It is very productive,
however, and the requirements for production are moderate.
White Clover. Fifty-two animal digestion and consump-
tion trials were completed on this forage. It was consumed at an
average rate of 118 pounds per 1,000 pounds of body weight
daily. This supplied 19.8 pounds of dry matter, 12.9 pounds of
TDN (sufficient for maintenance, and the production of approxi-
mately 18.4 pounds of 4 percent FCM), and 3.5 pounds of DCP.
Beyond the maintenance requirement, this amount of protein is
sufficient for production of approximately 14.4 pounds of 4 per-
Forages for Dairy Cattle in Florida
cent FCM. Thus when clover is used alone, the limiting factor
to the highest possible production would seem to be energy-
bearing nutrients. It would not be advisable to ignore completely
the protein content of supplementary feeds, but almost any
combination of feedstuffs would seem to be sufficient under most
conditions, provided adequate amounts are supplied. The swaid
was quite persistent, supplying forage from February through
June. Production requirements were moderate. The forage
persists well from year to year, but for best results careful
attention is required.
CONCLUSIONS AND RECOMMENDATIONS
All of the forages investigated are recommended for pasture
and greenchop where they are adapted. Proper supplementation
of all these forages will be necessary for efficient utilization.
In some cases the limiting factor appears to be energy, whereas
in others both energy and protein are severely lacking. All the
forages used herein were used at immature stages. Under these
conditions the difference between various cuttings was not
noticeable. The tables accompanying this publication should be
consulted when any of the forages are being used.
Supplementary concentrates should supply the additional di-
gestible protein and the total digestible nutrients necessary to
meet the requirements of the animal. These will vary consider-
ably to the type of forage used. Very careful management is
necessary for the maintenance of forage quality in all the species
studied. In practice, production requirements should be some-
what less than those presented here, since small plots and small
loads of forage were necessary.
1. Alston, C. 1960 Dairy Business Analysis-Eighteen Farms, Lower East
Coast. Fla. Agr. Ext. Service, Agr. Economics Mimeo Series 61-17.
2. A.O.A.C. Official Methods of Analysis. Assn. of Off. Agr. Chemists
(8th Ed.). Washington, D.C. 1955.
3. Blaser, R. E., G. E. Ritchey, W. G. Kirk, and P. T. D. Arnold. Experi-
ments with Napier Grass. Fla. Agr. Exp. Sta. Bull. 568. 1955.
4. Brody, S. Bioenergetics and Growth. Reinhold Publishing Corp., N.Y.,
N. Y. 1945.
5. Lofgren, G. P., and J. H. Meyer. A Method for Determining Total
Digestible Nutrients in Grazed Forage. J. Dairy Sci., 39:268. 1956.
14 Florida Agricultural Experiment Stations
6. Marshall, S. P. Whiteclover-pangolagrass and Whiteclover-Coastal
bermudagrass Pastures for Dairy Cows. Fla. Agr. Exp. Sta. Bull. 607.
7. Marshall, S. P. Value of Oat Pasture for Dairy Cattle. Fla. Agr. Exp.
Sta. Bull. 584. 1957.
8. Marshall, S. P., A. B. Sanchez, H. L. Somers, and P. T. D. Arnold.
Value of Pearlmillet Pasture for Dairy Cattle. Fla. Agr. Exp. Sta.
Bull. 527. 1953.
9. Marshall, S. P., and J. M. Myers. Irrigation of Whiteclover-pangola-
grass Pastures for Dairy Cows. Fla. Agr. Exp. Sta. Bull. 607. 1959.
10. Marshall, S. P., and P. T. D. Arnold. Value of Alyce Clover Pasture for
Lactating Dairy Cows. Fla. Agr. Exp. Sta. Bull. 542. 1954,
11. Pasture and Range Research Techniques. Comstock Publishing Assn.
Ithaca, N.Y. 1962.
12. Reaves, C. W. Contributions of Florida Dairy Farms to the Feed
Suppliers of Some Selected Milking Herds. M.S. Thesis. Univ. of Fla.