Ruminal fermentation and in situ starch digestion with high moisture corn, dry rolled grain sorghum or a mixture of these grains

An experiment was conducted to study the effects of feeding mixtures of high moisture corn (HMC) and dry-rolled grain sorghum (DRGS) on ruminal fermentation and site and the extent of starch digestion. Three ruminally fistulated steers were used in a replicated Latin square design. Dietary grain treatments were:(1) 100% HMC;(2) 67% HMC:33% DRGS; and (3) 100% DRGS. Starch and DM intake (P<0.01), and in situ rate of starch disappearance of DRGS (P<0.05) increased linearly as sorghum was added to the diet. Entodinium counts and total amylolytic activity tended to be higher (quadratic, P=0.20) in the mixture. VFA and molar proportion were not affected by the treatments. No associative effects were detected in ruminal starch digestion. Ruminal protozoa numbers were increased when DRGS and HMC were combined.