Effects of cimaterol on nitrogen retention and energy utilization in lambs.

Fifty-two weaned lambs were used in a comparative slaughter feeding trial and six lambs in a concurrent digestibility trial to investigate the effects of cimaterol on nitrogen retention and energy utilization. Cimaterol (CIM) was administered in the feed at 10 ppm for 90 and 14 d, respectively, in a comparative slaughter feeding trial and in a digestibility trial. No difference was found in dry matter digestibility. Nitrogen retention in the CIM group (739 mg/Wkg.75/d) was greater (P less than .01) than that of the control group (321 mg/Wkg.75/d). This difference was accounted for primarily by reduced nitrogen loss in urine of the CIM group. Cimaterol improved growth rate and feed/gain ratio, although these improvements were only evident during the first 42 d of the 90-d feeding trial. The improvement in growth performance of the CIM group was associated with increased protein gain in the empty body (40.2 g/d, P less than .01) as well as in carcass (26.9 g/d, P less than .01), compared with 30.1 and 14.5 g/d of the control group. Cimaterol decreased (P less than .01) fat gain (91.4 vs 109.9 g/d), total daily energy gain (1.08 vs 1.22 Mcal) and energy gain/kg gain (4.17 vs 5.11 Mcal) compared with the control. Feeding CIM increased (P less than .01) estimated fasting heat production (73 vs 64 Kcal/Wkg.75) and metabolizable energy requirement for maintenance (110.2 vs 92.7 Kcal/Wkg.75) over the control.(ABSTRACT TRUNCATED AT 250 WORDS)