Castration and morbidity and their effects on performance, carcass quality, and price differentials for bulls and steers

When purchasing feeder calves, bulls are typically discounted relative to steers. Determining the appropriate discount is difficult. Being able to calculate this discount under varying conditions would help stocker operators maintain a greater level of profitability or recognize opportunities to make more profit when excessive discounts are being applied. The objectives of this study were to determine how castration timing affects performance, morbidity, and carcass quality and how morbidity affects performance and carcass quality. Ordinary least squares and logit models were estimated to quantify the effects of various management and environmental factors on performance, morbidity, and carcass quality. These estimates were used to calculate price discounts for bulls relative to steers, for both a short backgrounding period and when ownership is retained until slaughter. Results confirm that late-castrated bulls exhibit diminished performance and increased morbidity probabilities relative to early-castrated bulls. Increased morbidity also decreases ADG. However, castration timing and morbidity during the backgrounding period have minimal effects on carcass quality, with morbidity only affecting hot carcass weight, whereas castration timing only affects days to market and hot carcass weight. Based on 2009 market conditions, bulls should be discounted at feeder calf sales compared with steers. The average calf arrived at 209 kg. At this BW, bulls should be discounted (P < 0.01) $0.11/ kg relative to the same BW steers. The discount increases (P < 0.01) to $0.12/ kg for 170-kg calves and decreases (P < 0.01) to $0.08/kg for 250-kg calves. If ownership is retained through slaughter, required discounts change (P < 0.01 for all) to $0.14/kg, $0.04/kg, and $0.17/ kg, respectively, for average- (209 kg), light- (170 kg), and heavy-BW (250 kg) calves.