Abstract: Objectives of this study were to compare supplementation of corn or soybean hulls against changes in apparent digestion and ruminal parameters. Six ruminally cannulated steers (initial BW 182 ± 24.8 kg) received bermudagrass Hay (HAY); hay, corn (0.445 % Body Weight (BW) and Soybean Meal (SBM, 0.127% BW; CORN); or hay, Soybean Hulls (SBH; 0.607 % BW) and SBM (0.127 % BW; HULLS) using 3×3 Latin Rectangle. At 0, 2, 4, 6 and 8 h post-feeding supplements, ruminal fluid was analyzed for pH, Volatile Fatty Acids (VFA) and NH3-N. Feeds ruminally incubated for 0, 2, 4, 6, 8, 16 and 24 h were analyzed for Dry Matter (DM), Neutral Detergent Fiber (NDF), Acid Detergent Fiber (ADF) and Crude Protein (CP) disappearance. Ruminal pH decreased (p< 0.01) when steers consumed CORN (6.54-5.89) or HULLS (6.63-6.07). At 0 h, no differences (p< 0.52) in total VFA occurred among HAY, CORN and HULLS (138.3, 143.9 and 149.2 mM L 1, respectively). At 4, 6 and 8 h post-feeding, VFA concentrations were greater (p< 0.001) when steers consumed HULLS than CORN and both were greater than those fed HAY. Disappearance ratios of hay DM, NDF and CP did not differ for HAY, CORN, or HULLS (ranging from 0.773-1.175) whereas hay ADF ratios were greater (p< .04) from 6-16 h when feeding HULLS. Data suggest that, compared to corn, SBH produce positive associative effects that may support more efficient ruminal digestion of low-quality bermudagrass hay. In situ incubation revealed limited effects upon hay digestion, under parameters of the current trial.
V.T. Nguyen , A.I. Orr , D.G. St. Louis and B.J. Rude , 2007. Supplementing Corn or Soybean Hulls to Cattle Fed Bermudagrass Hay II: In situ Disappearance and Ruminal Dynamics. Journal of Animal and Veterinary Advances, 6: 1125-1134.