Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/7/1999
Publication Date: 6/1/2000
Citation: Krehbiel, C.R., Kreikemeier, K.K., Ferrell, C.L. 2000. Influence of Bos indicus crossbreeding and cattle age on apparent utilization of a high-grain diet. Journal of Animal Science. 78:1641-1647. Interpretive Summary: Previous reports have suggested that Bos indicus and Bos indicus crossbred utilize low quality forage diets more efficiently and high concentrate diets less efficiently than Bos taurus cattle. Results from this study indicate that utilization of a high-grain diet is similar in Bos indicus crossbred and Bos taurus cattle. Bos indicus crossbreds has similar daily gain, feed intake and feed efficiency, but lower quality grade than Bos taurus (MARC III) steers. No difference in digestion of nutrients was observed in the study. Steer age had greater effects than biological type. Calves ate less feed, grew slower, but were more efficient than yearlings.
Technical Abstract: Ten Bos indicus x MARC III and 10 MARC III steers were used in a 2 x 2 factorial design to determine whether cattle age or Bos indicus crossbreeding influence site of digestion of a high-grain diet. Initially, five Bos indicus x MARC III and five MARC III steers were fitted with duodenal cannulas and adapted to a 95% concentrate diet that was offered for ad libitum consumption for a 237-d feeding period (calves). During th feeding period, duodenal and fecal samples were collected during 4-d periods beginning on d 14, 67, 137, and 228. The remaining 10 steers were fed a forage-based diet for a targeted daily gain of .6 to .7 kg for 210 d (yearlings). Following this period, yearling steers were duodenally cannulated and adapted to the 95% concentrate diet. Yearling steers had ad libitum access to feed for 165 d, and samples were collected during 4-d periods beginning on d 13, 42, 102, and 159. Dry matter intake was 9.8 and d7.5 kg/d and daily gain was 1.35 and 1.16 kg in yearlings and calves, respectively. Apparent OM digestion in the stomach was greater in yearlings than in calves. In contrast, postruminal disappearance as a percentage of OM intake was greater in calves than in yearlings. Duodenal flows of total N, microbial N, nonmicrobial N, and total amino acids and total tract N digestibility were not affected by age or Bos indicus crossbreeding. Fecal N excretion was greater in yearlings than in calves. Results of this experiment suggest little effect of Bos indicus influence on utilization of a high-grain diet. However, more feed is digested in the rumen of yearlings than of calves consuming a high-grain diet.