Dl. Galloway et al., FEED-INTAKE AND DIGESTIBILITY BY CATTLE CONSUMING BERMUDAGRASS OR ORCHARDGRASS HAY SUPPLEMENTED WITH SOYBEAN HULLS AND(OR) CORN, Journal of animal science, 71(11), 1993, pp. 3087-3095
Effects of supplementing cattle consuming tropical or temperate grass
with corn and(or) soybean hulls on feed intake and digestibility were
determined. In Exp. 1, eight Holstein steer calves (210 +/- 9.2 and 26
9 +/- 9.4 kg initial and final BW, respectively), in two simultaneous
Latin squares, were given ad libitum access to bermudagrass (B) or orc
hardgrass (O) hay without supplementation or with (DM basis) .5% of BW
of ground corn (C), .7% of BW of soybean hulls (H), or .25% of BW of
corn plus .35% of BW of soybean hulls (CH). Total OM intake was greate
r (P <.05) with than without supplementation (5.05, 6.04, 5.95, 6.06,
6.04, 6.81, 6.61, and 6.69 kg/d), and digestible OM intake was affecte
d by forage source (P < .05), mixing of supplement types (CH versus th
e mean of C and H; P < .09), and the forage source x supplementation i
nteraction (P < .09; 2.65, 3.40, 3.33, 3.46, 3.71, 4.14, 3.98, and 4.3
0 kg/d for B, B-C, B-H, B-CH, O, O-C, O-H, and O-CH, respectively). To
tal tract NDF digestibility was greater (P < .05) for O than for B die
ts and for H than for C (56.4, 53.9, 58.1, 56.9, 68.5, 64.9, 67.7, and
69.6% for B, B-C, B-H, B-CH, O, O-C, O-H, and O-CH, respectively). In
Exp. 2, mature cannulated beef cattle (524 +/- 1.6 kg BW) were used i
n a design similar to Exp. 1 with comparable dietary supplement levels
. The concentration of total VFA and acetate:propionate in ruminal flu
id did not differ between C and H. Duodenal microbial N also did not d
iffer among supplement treatments, but postruminal OM digestibility wa
s greater (P < .06) for C than for H with both forages. In conclusion,
digestible OM intake was improved similarly by supplementing growing
steers consuming moderate-quality, temperate, or tropical grass hay wi
th .5% of BW of corn or .7% of BW of soybean hulls. A mixture of corn
and soybean hulls increased digestible OM intake with both forage sour
ces relative to the mean of C and H.