U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska
Date of this Version
1987
Abstract
Seventy-seven tleifers weighing about 200 kg were assigned randomly to 1) intact control (C), 2) ovariectomized (OVX), 3) immunized against estradiol (BSA-E), 4) BSA-E + trenbolone acetate (BSA-E+TBA), 5) TBA or 6) ovx + TBA groups. The objective of the study was to determine the effects of ovariectomy, immunoneutralization of estradiol and trenbolone acetate treatment on growth rate and carcass merit. Heifers were fed a corn-corn silage diet and were slaughtered when treatment groups attained live-animal weights of 433 kg. Observations of rate of growth, efficiency of feed conversion, characteristics of carcasses and characteristics of organoleptic properties of the cooked meat were made. Average daily gains (ADG) were similar in the control and OVX groups and tended to be less than in other treatment groups (P<.36). Although not statistically significant, the observed mean for the BSA-E+TBA treatment suggests improved ADG and TDN per unit of gain, indicating a possible immunization X TBA interaction. Data also suggested that heifers implanted with TBA had increased ADG and efficiencies of gain. Possibly, immunoneutralization of endogenous estradiol can improve ADG as compared with control and OVX groups. Treatments had no effect on color or texture of lean muscle at the 12th rib interface. The OVX + TBA group had less (P<.O1) 12th rib fat cover than other groups and lower percent fat in the rib than C. The BSA-E+TBA and TBA groups also possessed larger (P<.02) longissimus muscle areas than the control group. Observations of juiciness, tenderness and flavor were similar among all treatments. Results indicate that implanting heifers with TBA and (or) immunizing against endogenous estradiol may provide opportunities to increase gains, feed conversions and lean-to-fat ratios in heifers.
Comments
Published in J. Anim. Sci. (1987)64:1434-1440