Relationships between feedlot health, average daily gain, and carcass traits of Angus steers1

Angus steers (n = 17,919) fed at a single feedlot in southwestern Kansas between 1997 and 2007 were used to evaluate the relationships between feedlot health, ADG, and carcass traits. Cattle were not commingled and were predominantly preconditioned and backgrounded before shipment to the feedlot. Morbidity decreased and ADG increased with increasing initial BW (P < 0.01); percentage Choice was related (linear P = 0.02) to arrival BW in steers that were not treated for disease, but with only 2.8% units separating the least (< 295 kg) and the greatest percentage Choice groups (375-409 kg). There were linear and quadratic decreases in ADG, final BW, HCW, QG, and YG with increased number of times treated (P < 0.02). With decreasing QG there were linear and quadratic decreases in ADG, final BW, HCW, and YG. Increasing YG from YG 1 and 2 to YG 3 increased percentage Choice by 16.1 points, and there was an additional 1.6-point increase moving to YG 4 and 5 (linear and quadratic, P < 0.01). Average daily gain was very similar among cattle that graded Prime, Choice, and Select, suggesting that performance and QG are not genetically linked; instead, much of the difference in QG can be explained by differences in YG.