title: Influence of Bos indicus crossbreeding and cattle age on apparent utilization of a high-grain diet.
abstract: Ten Bos indicus x MARC III (initial BW = 303 +/- 25 kg) and 10 MARC III (initial BW = 322 +/- 16 kg) 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 the 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 7.6 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 (P < .01) in yearlings than in calves. In contrast, postruminal disappearance as a percentage of OM intake was greater (P = .05) 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 (P > .05) by age or Bos indicus crossbreeding. Fecal N excretion was greater (P < .01) 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.
authors.affiliation: USDA, ARS, U.S. Meat Animal Research Center, Clay Center, NE 68933, USA. Kclinto@okstate.edu
authors.forename: C R
authors.initials: CR
authors.lastname: Krehbiel
authors.forename: K K
authors.initials: KK
authors.lastname: Kreikemeier
authors.forename: C L
authors.initials: CL
authors.lastname: Ferrell
mesh_terms: D000375:Aging / Q000378:metabolism*; D000821:Animal Feed; D000818:Animals; D001947:Breeding; D002417:Cattle / Q000378:metabolism*; D004040:Dietary Carbohydrates / Q000378:metabolism*; D004063:Digestion; D004386:Duodenum / Q000737:chemistry; D002523:Edible Grain / Q000378:metabolism*; D005243:Feces / Q000737:chemistry; D008297:Male; D009584:Nitrogen / Q000378:metabolism; D011897:Random Allocation
chemical_list: D004040:Dietary Carbohydrates; D009584:Nitrogen