Influence of Roughage Level and Corn Processing Method on Microbial Protein Synthesis by Beef Steers

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Abstract
Two trials were conducted to determine the influence of roughage level and corn processing method on the efficiency of nitrogen (N) utilization by beef steers fed high concentrate rations. In trial 1, abomasally cannulated steers were fed rations containing whole shelled corn (WSC) with cottonseed hull (CSH) levels of 0, 7, 14 and 21% and in trial 2, rations contained steam flaked (SF) and dry rolled (DR) corn with 0 and 21% CSH levels. Lignin was used as a marker for determination of digesta passage through the abomasum. In trial 1, the grams of microbial protein synthesized per 100 g dry matter fermented in the rumen (MP/DDM) were 7.5, 10.3, 11.8 and 12.7 for rations 0, 7, 14 and 21, respectively. More of the N intake bypassed the rumen undegraded (BPN) on rations 14 and 21 resulting in more (P<.05) total protein reaching the intestine (AP). In trial 2, MP/DDM for main effects, SF, DR, 0 and 21 were 7.0, 10.5, 6.3 and 11.2, respectively. N was absorbed from the rumen on all rations, but the N loss was less (P<.01) on the 21% CSH rations. BPN and AP were higher (P<.05) on the 21% roughage rations and tended to be higher for DR than SF corn. Copyright © 1976. American Society of Animal Science . Copyright 1976 by American Society of Animal Science.