LONG-TERM EFFECTS OF CIMATEROL IN FRIESIAN STEERS .2. CARCASS COMPOSITION AND MEAT QUALITY

The objectives of this study were to examine the effects of long-term administration of cimaterol to steers from 4 wk of age until slaughter at target live weights of 275, 375, and 475 kg on 1) carcass composition; 2) distribution and growth of the dissectible lean, fat, and bone; and 3) selected meat quality traits. Ninety calves were allocated to either control or cimaterol (4 ppm) treatment with 15 from each treatment scheduled for slaughter at the above target live weights. Of the 90 calves, 73 carcasses were dissected. Cimaterol increased the proportion of lean in the carcass of the three target slaughter groups from 653, 629, and 612 g/kg in control steers to 728, 728, and 723 g/kg in treated steers, respectively, and decreased the proportion of fat from 134, 169, and 197 g/kg in control steers to 88, 86, and 99 g/kg in treated steers, respectively. Cimaterol increased the longissimus muscle area from 46.4, 56.7, and 62.4 cm2 in control steers to 61.0, 73.4, and 90.8 CM2 in treated steers in the three target slaughter groups, respectively. The allometric growth coefficients for total lean, bone, and fat were .987, .869, and 1.406, respectively, for treated animals and .898, .771, and 1.654, respectively, for control animals. Cimaterol increased the 2-d drip loss and the fiber-optic probe value of longissimus muscle. Shear force values were 55, 145, and 118% higher in the treated animals in the three target slaughter groups, respectively. It is concluded that 1) cimaterol inclusion in the diet resulted in an increase in lean meat accretion, a decrease in adipose tissue deposition, and a reduction in meat quality and 2) compared to short-term treatment with cimaterol, there are no benefits to be gained in terms of carcass composition from long-term treatment.