FLORIDA^ ^ URAL EXPERIMENT STATIONS
S evi e, Florida
Dairy Science Mimeo Report DY 64-3
P May 12, 1964
VOLUNTARY CONSUMPTION AND DIGESTIBILITY OF FORAGES USED AS FEEDS
FOR DAIRY CATTLE IN FLORIDA
J. M. WingLi
The pressures of modern civilization heighten the need for efficiency in all
phases of livestock production. Population pressures are increasing the
over-all demand for food. The genetic merit of dairy cattle has improved
immensely and further advancements in animal quality are imminent. Costs
of labor and general expenses make it necessary for all the heriditary ef-
ficacy of the cattle to be utilized. This makes feeding to productive ca-
Increased production of human food by dairy cattle and other livestock may
come, among other sources, from the development of higher producing feed
crops, and from more efficient utilization and conversion of the feed. It
appears that the first condition is being met. Various experiments with
dairy cattle have shown that improved forages produced as much as 10 times
the nutrients which were derived from native pastures. (3, 7, 8, 9, 10,
11). Further enrichment of forage productivity and caliber 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.
Since previous evaluations of the forages have involved mainly a quantitative
appraisal of the yield; and the qualitative features have been largely ig-
nored, forages even on progressive dairy farms might not have been used as
effectively as possible. A recent economic survey indicated that many dair-
ies which operated mainly or entirely on purchased feeds were more profitable
than comparable operations which utilized green forage extensively (1).
The purpose of the work presented herein therefore was to determine the a-
mount of forage which is likely to be consumed daily by dairy cattle which
have free access to it and the extent to which the nutrients contained there-
in are digested. Using such data, it should be possible to formulate the
most effective supplements possible under given conditions,
Associate Dairy Husbandman,
Included in the study were various forages which are likely to be used as
either pastures or greenchop. Improved varieties were planted 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 steers,
dry cows, or large heifers. Refusal likewise was weighed and analyzed. Con-
sumption rates then were computed on the basis of 1000 lb, of body weight.
Most of the animals used for this study weighed very close to 1000 Ib and
corrections for consumption were made according to variations in body surface
as suggested by Brody (4). This was necessary because consumption of feed
varies according to surface rather than directly with weight.
Although lactating cows possibly will consume slightly different amounts,
both their requirements for nutrients and the availability of feeds from
other sources will increase. Thus this would not seem to cause a signifi-
cant error. The digestibility determinations were made by indicator methods
employing either chromium oxide or indigestible plant chromogens according
to procedures approved by the American Society of Agronomy, American Dairy
Association, American Society of Animal Production, and the American Society
of Range Management (5). 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 (6) were used to determined
the total digestible nutrients (TDN) of the feeds. Separate determinations
were made for digestibility of dry matter and digestible crude protein (DCP).
Data are presented in Table 1.
Five grass type forages, two legumes, one legume mixture, and three grass-
legume mixtures were investigated by means of feeding and digestibility ex-
periments. The rates of consumption and digestibility have been summarized
in Table 1. They are presented on both the dry and fresh basis. When used
in connection with feeding standards, this information is designed to fa-
cilitate the formulation and feeding of rations to various classes of cat-
tle. Since the amount of TDN and digestible crude protein 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 should
be determined without difficulty. Of course individual animal variations
will make adjustments necessary. Moreover, fertilization and stage of ma-
turity of the plants at harvest are related to protein and the total diges-
tible nutrient content. All forages included in this study were raised ac-
cording to recommended practices and utilized at what appeared to be the most
nutritious stage within the limitations imposed by normal management details.
Oats Eighty-five digestion and consumption trials were completed on this
forage. An average of 79.8 pounds of forage containing 14.2 pounds of dry
matter, 8.9 pounds of TDN, and 1.5 pounds of DCP were consumed per 1000
pounds of body weight daily. The TDN contained therein was sufficient for
about 9 pounds of 4% milk in addition to maintenance requirements. The pro-
tein consumption above maintenance requirements was sufficient for production
of approximately 13 pounds of 4% milk. This is a very good roughage feed
for dairy cattle but efficient use of oat forage would depend upon additional
feed which is very high in total digestible nutrients and digestible pro-
teins, and which is supplied in relatively large amounts to high producing
Table 1. Consumption and Digestibility of Typical Florida Forages by Dairy Cows
Digestible Intake Per 1000 Lbs.
% Digesti- T D N Protein Body Weight
No. of % Dry ability of % Dry % Fresh % Dry % Fresh Dry No. of
Feed Animals Matter Dry Matter Basis Basis Basis Basis Forage Matter TDN DCP Cuttings
Oats plus Clover
Oats plus Alfalfa
Oats plus Alfalfa
Alfalfa plus Clover
more cuttings or angola are possible.
* Figures in second line represent
,,- Under favorable conditions many
Oats plus clover Twenty-three digestion and consumption trials were com-
pleted on the combination sward of oats and clover. Per 1000 Ib of body
weight the daily consumption was 109.4 Ib of forage which provided 18.2 lb
of dry matter, 10.9 lb TDN, and 1.9 lb of DCP. Above maintenance require-
ment, the TDN was sufficient for production of about 11.8 lb of 4% milk.
The protein consumption beyond maintenance requirements was sufficient for
production of approximately 18.6 Ib of 4% milk. Thus, adequate amounts of
concentrate feeds which are high in energy and medium high in protein con-
tent are recommended for supplementing this type of forage.
Oats plus alfalfa Thirty-eight digestion and consumption trials were com-
pleted on this forage. The total amount of feed consumed averaged 98.7 Ib
per 1000 lb of body weight daily. This amount supplied 17 Ib of dry matter,
10.7 Ib of TDN, 2.1 lb of DCP. The TDN was sufficient for maintenance and
production of about 11.6 3b of milk. The digestible crude protein was suf-
ficient for maintenance and the production of 21.0 lb of 4% milk. 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 supplementary feed should be high in energy producing
Oats plus alfalfa plus clover Data in this case are somewhat limited since
only four animal trials were completed. It appears, however, that this is a
very favorable combination since an average of 133.9 lb of forage per 1000
lb of body weight daily were consumed. It supplied an energy intake compar-
able to those combinations described above (10.9 Ib) and sufficient protein
beyond the maintenance requirements for the production of approximately 28,6
lb of 4% milk. Thus a concentrate mixture which is moderate in protein con-
tent but high in energy bearing nutrients would seem to be appropriate for
supplementing this mixture.
White clover Fifty-two animal digestion and consumption trials were com-
pleted on this forage. It was consumed at an average rate of 117.6 lb per
1000 lb of body weight daily. This supplied 19.8 Ib of dry matter, 12.9 Ib
of TDN (sufficient for maintenance, and the production of approximately 18.4
Ib of 4% milk), and 3.5 lb of digestible crude proteins. Beyond the main-
tenance requirement this amount of protein is sufficient for production of
approximately 41.4 lb of 4% milk. Thus when clover is used alone, the lim-
iting factor to the highest possible production would seem to be mainly energy
bearing nutrients. It would not be advisable to completely ignore the pro-
tein content of supplementary feeds but almost any combination of feedstuffs
would seem to be sufficient under most conditions, provided adequate amounts
Alfalfa Eighty-eight consumption and digestion trials were completed with
alfalfa. Ninety-nine pounds per 1000 lb body weight daily were consumed and
this supplied 12.1 Ib of TDN sufficient for maintenance and the production of
about 16 Ib of 4% milk, and 2.3 Ib of protein which is enough for body main-
tenance and production of about 24 lb of 4% milk. A high energy medium pro-
tein feed would be adequate for supplementing greenchop alfalfa.
Alfalfa plus clover Fourteen determinations were made with this legume
combination. The forage was very palatable and 118.5 lb per 1000 lb body
weight were consumed daily. This supplied 16.6 lb of dry matter, 9.8 lb of
TDN (sufficient for maintenance and production of slightly less 9 lb of 4%
milk), and 3.1 lb of protein enough for maintenance and almost 36 Ib of 4%
milk. In this case the main limiting factor to be considered in supplemen-
tary feeds is the energy bearing nutrients.
Pearlmillet Sixty animal digestion and consumption trials were completed
with this forage. Per 1000 Ib body weight daily, the animals consumed an
average of 125.4 lb of herbage. This supplied 19.5 lb of dry matter con-
taining 12.0 Ib of TDN, and 1.8 lb of digestible crude proteins. The lim-
iting 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 lb of milk. Thus care should be taken to supply supplementary pro-
tein as well as energy to cows consuming mainly pearlmillet.
Green Corn Twenty-one trials were completed with green corn as the exper-
imental feed. An average of 102 lb per 1000 lb body weight daily were con-
sumed. This supplied 15.8 lb of dry matter, 9.7 lb of TDN, and .9 lb of di-
gestible crude protein. Supplementary feeds to green corn therefore should
be high in both energy bearing nutrients and digestible crude proteins.
Pangolagrass Eight trials were completed with pangolagrass. This forage
was in the pre-blcom stage, green, and highly fertilized. Unfavorable weather
conditions followed this experiment, however, and thus only one feeding period
with eight animals was completed under favorable conditions. Several cuttings
of pangola per season are possible. Under conditions of this experiment,
animals consumed an average of 73.9 lb of pangolagrass per 1000 lb of body
weight daily. This provided 13.8 lb of dry matter, 9.4 lb of TDN, and 1.2
lb of DCP. Pangolagrass should be supplemented with concentrate feeds which
are high in both energy bearing nutrients and digestible crude proteins for
Sart Sargo Eight animal digestion trials were completed with Sart Sargo.
Sixty pounds of forage 11.4 lb of dry matter, 16.5 lb of TDN, and 0.7 Ib of
DCP were consumed 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.
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 ap-
pears to be mainly energy, whereas in others both energy and protein are se-
verely lacking. All the forages used herein were used at immature stages.
Under these conditions the difference between various cuttings vas not notice-
able. The table accompanying this publication should be consulted when any
of the forages are being used. The supplementary concentrates should supply
the additional digestible protein and total digestible nutrients necessary
to meet the requirements of the animal. These will vary considerably accord-
ing to the type of forage used. Very careful management is necessary for the
maintenance of forage quality in all the species studied.
1. Alston, C. 1960 Dairy Business Analysis Eighteen Farms, Lower East
Coast. Fla. Agr. Ext. Service, Agr. Economics Mimeo Series 61-17. 1960.
2. A.O.A.C. Official Methods of Analysis. Assn. of Of Agr. Chemists
(8th Ed.). Washington, D. C. 1955.
3. Blaser, R. E., Ritchey, G. E., Kirk, W. G., and Arnold, P. T. D. Exper-
iments with Napier grass. Fla. Agr. Exp. Sta. Bull. 568. 1955.
4. Brody, S. Bioenergetics and Growth. Reinhold Publishing Corp., N. Y.
5. Comstock Publishing Associates, Itiaca, New York. Pasture and Range
Research Techniques. 1962.
6. Lofgren, G. P., and Meyer, J. H. A method for determining total diges-
tible nutrients in grazed forage. J. Animal Sci., 39:268. 1956.
7. Marshall, S. P., Sanchez, A. B., Somers, H. L., and Arnold, P. T. D.
Value of pearlmillet pasture for dairy cattle. Fla. Agr. Exp. Sta. Bull.
8. Marshall, S. P., and Arnold, P. T. D. Value of alyce clover pasture
for lactating dairy cows. Fla. Agr. Exp. Sta. Bull. 542. 1954.
9. Marshall, S. P. Value of oat pasture for dairy cattle. Fla. Agr. Exp.
Sta. Bull. 584. 1957.
10. Marshall, S. P., and Myers, J. M. Irrigation of whiteclover-pangola-
grass pastures for dairy cows. Fla. Agr. Exp. Sta. Bull. 607. 1959.
11. Marshall, S. P. Whiteclover-pangolagrass and whiteclover-coastal ber-
mudagrass pastures for dairy heifers. Fla. Agr. Exp. Sta. Bull. 613.
12. Reaves, C. W. Contributions of Florida dairy farms to the feed suppliers
of some selected milking herds. M.S. Thesis. Univ. of Florida. 1956.