Abstract
The influence of roughage level and corn processing method on the site and extent of digestion of dry matter (DM), organic matter (OM), cellulose and starch was studied using four Hereford steers fitted with ruminal and abomasal cannuiae in a 4 × 4 latin square design. Corn was fed steam flaked (SFC) or dry rolled (DRC) at roughage levels (cottonseed hulls) of 0 and 21% in a 2 × 2 factorial arrangement of treatments. Lignin was used as a marker for calculation of ruminal digestibilities. Ruminal DM digestibilities were about 13 percentage units higher (P<.01) for rations containing SFC than DRC and approximately 10 percentage units higher (P<.05) for rations containing 0 as compared to 21% cottonseed hulls. Total DM digestibilities were 7 percentage units higher (P<01) for SFC than DRC and were 9 percentage units higher (P<.01) for the 0 vs the 21% roughage rations. Some 93 to 97% of total cellulose digestion occurred in the rumen. Ruminal and total OM and DM digestibilities were similar in pattern but OM digestibilities tended to be higher. Mean ruminal and total digestibilities of starch for main effects SFC and DRC were 91.6 and 99.0 and 71.7 and 93.6%, respectively. The higher roughage level reduced starch digestibility in the intestine (P<.01) and in the entire tract (P<.05). Copyright © 1976. American Society of Animal Science . Copyright 1976 by American Society of Animal Science.