Efficiency of food utilization and carcass characteristics of steers marketed at different weights

Abstract

ABSTRACTHereford and Charolais x Hereford steer calves were given an all-concentrate diet ad libitum. The Hereford steer calves were marketed at about 400, 440 and 475 kg live weight. The Charolais x Hereford steer calves were marketed at about 525, 570 and 610 kg. For each kg increase in slaughter weight of Hereford steers, the digestible energy required per unit live weight gain increased by 0·024 (s.e. 0·009) MJ, the killing-out proportion increased by 0·22 (s.e. 0·08) g/kg, and the backfat thickness by 0·004 (s.e. 0·002) cm. The area of m. longissimus increased by 0·245 (s.e. 0·037) cm2 and 0·139 (s.e. 0·048) cm2 for Hereford and Charolais X Hereford steers, respectively, for each kg increase in carcass weight. Among Hereford steers, mean backfat thickness as indicated by carcass grade scores (score of 1 to 4 as backfat increases) at the two lowest slaughter weights were similar and lower than scores at the high weight. Among Charolais X Hereford steers, the carcass grade was not influenced by slaughter weight. Slaughtering Hereford and Charolais x Hereford steers at light weights does not ensure that all the carcasses will be lean when the cattle are given a high concentrate diet to appetite from weaning to slaughter.