Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: April 2, 2007
Publication Date: July 8, 2007
Citation: Coleman, S.W., Phillips, W.A., Chase, C.C., Riley, D.G. 2007. Feed efficiency of tropically adapted breed and breed cross steers when fed in the southern plains. Journal of Animal Science Supplement.85:(1):Paper No. 213 Technical Abstract: Beef cows in the subtropical USA require that they be adapted to the stressors of the environment. However, calves produced in the region are usually grown and finished in more temperate regions. The objective of this paper is to determine the feed efficiency of steers from a 3-breed diallel mating of Angus (A), Brahman (B) and tropically adapted Romosinuano (R), a Criollo Breed native to Colombia. Calves (n=261) born over 3yr from 2002-04 were straightbred AA, BB and RR, or crossbreds (RB, BR, RA, AR, BA, AB; letters indicate breed of sire and dam, respectively). Steer calves were weaned in September and shipped 2025 km to El Reno, OK for growing and finishing. After grazing wheat pasture until May, 2003, they were finished on a conventional feedlot diet using Calan headgates to obtain individual feed intake. Steers were serially harvested at three times each year, ranging from 93 to 168 days on feed. Feed efficiency was calculated as feed per unit gain (FdGn) and as residual feed intake (RFI). The MIXED model included effects of year, stocker treatment, and replicate. Days on feed and calf age at the beginning of the feedlot phase were fit as continuous variables. Sire within breed was the random term. Significance is denoted by + (P<0.10), *(P<0.05) or **(P<0.01). Direct effects for initial and final weight and daily gain were 43**, 16, and -21+;19+;61**, and 0.31**; and -62**, -77** and -.10 kg for A, B, and R, respectively. Direct effects foir daily DM intake, FdGn, and RFI were -1, 2.16*, and 0.48+; -.25, -2.73**, and -.44=; and 1.25+, 0.57, and -.05 for A. B. and R steers. Heterosis (P< 0.001) was noted for all breed combinations for initial and final weights, but not for rate of gain. There was negative heterosis ()P<0.01) for intake by A-B and for B-R crosses. There was no Heterosis for feed efficiency. In conclusion Brahman influenced steers appear to be more efficient than Angus and Romosinuano was intermediate.