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Everglades Station Mimeo Report 58-8 November 5, 1957
A METHOD OF ESITMATTNG FORAGE CONSUMPTION BY GRAZING CATTLE
R. W. Kidder and R. J. Alien, Jr.
The total digestible nutrient requirement of cattle for maintenance is pro-
portional to the 0.7 power of the live weight (1)(4), with the daily maintenance
requirement for a 1000 pound steer being 7.9 pounds of total digestible
nutrients(l). Since the 0,7 power of 1000 is 125.9, this divided by 7.9 gives
the factor 15.94. Thus the daily maintenance requirement of total digestible
nutrients for animals of any weight can be calculated by the formula:
T,D.N. = WO in which T.D.N. is the average daily maintenance requirement, in
pounds, 15.91 for an animal of the weight represented by W (3).
To simplify the application of this formula to the average weights of groups
of grazing cattle, a graph was prepared on which the animal weight read on the
horizontal scale to the nearest five pounds and the corresponding TID.N. require-
ment determined to .02 pounds on the vertical scale from the plotted curve.
8 The average requirement for gain was
calculated at 3.53 pounds of T.D.N. per
pound of body weight. When losses
occurred a deduction of 2.73 pounds was
made for each pound loss in weight (5).
7 Through analysis of the grasses it
was estimated that Caribgrass and Para-
grass contained 11.88 percent of total
-* digestible nutrients while St. Augustine-
grass contained 14.67 percent (2)e This
/ difference was fundamentally due to.
6 approximately four percent more dry
/ matter in the St. Augustinegrass.
/- Calculations based on this procedure
Indicate that the cattle consume some-
where near the same volume of each grass
-- / but that the superior response on St.
Augustine may be associated with the
S / digestible nutrient content of the two
grasses. The significance of frost
/ injury which eliminates grazing on Carib-
S / grass and Paragrass for variable winter
/ periods is not emphasized by these
/ methods of measuring pasture yields.
WEIGHT IN POUNDS
WEIGHT IN POUNDS
1. 1945 Brody S., et. al. Bioenergetics and Growth. Mo. Res. Bul. 220.
2. 1945 Kidder, R. W. Composition and Digestible Nutrient Content of Napier
Grass Leaves. Jour. Agr. Res. Vol.70 No.3.
3. 1946 Kidder, R. W. A Proposed Method of Measuring Pasture Yields with
Grazing Cattle. Jour. An. Sci. Vol.5 No.3.
4. 1956 Morrison, F. B. Feeds and Feeding. 22nd Edition.
$. 1934 Knott, J. C. et. al. Methods of Measuring Pasture Yields with Dairy
Cattle. Wash. Agr. Expt. Sta. Bul. 295.
E1S 58-8 300 copies