Factors associated with age at slaughter and carcass weight, price, and value of dairy cull cows

The sale of cull cows contributes to the overall profit of dairy herds. The objective of this study was to quantify the factors associated with slaughter age (mo), cow carcass weight (kg), price ((sic)/kg of carcass weight), and value ((sic)/head) of dairy cull cows. Data included 20,995 slaughter records in the period from 2003 to 2011 of 5 different breeds: 2 dairy [Holstein Friesian (HF) and Brown Swiss (BS)] and 3 dual-purpose [Simmental (Si), Alpine Grey (AG), and Rendena (Re)]. Associations of breed, age of cow (except when the dependent variable was slaughter age), and year and month of slaughter with slaughter age, carcass weight, price, and value were quantified using a mixed linear model; herd was included as a random effect. The seasonal trends in cow price and value traits were inversely related to the number of cows slaughtered, whereas annual variation in external factors affected market conditions. Relative to BS cows, HF cows were younger at slaughter (73.1 vs. 80.7 mo), yielded slightly lighter carcasses (242 vs. 246 kg), and received a slightly lower price (1.69 vs. 1.73 (sic)/kg) and total value (394 vs. 417 (sic)/head). Dual-purpose breeds were older and heavier and received a much greater price and total value at slaughter (521, 516, and 549 (sic)/head, respectively for Si, Re, and AG) than either dairy breed. Of the dual-purpose cows, Si carcasses were heavier (271 kg), whereas the carcasses of local breeds received a higher price (2.05 and 2.18 (sic)/kg for Re and AG, respectively) and Alpine Grey cows were the oldest at slaughter (93.3 mo). The price per kilogram of cull cow carcasses was greatest for very young cows (i.e., <3 yr of age) and the differential in price and value between younger and older cows was greater in dual-purpose than in dairy breeds. Large differences in cull cow whole carcass value (carcass weight x unit price) among dairy breeds suggest that such a trait could be considered in the breeding objectives of the breeds.