Effects of trenbolone acetate and hexoestrol on live-weight gain, and serum hormone and metabolite concentrations, in steers

Abstract

Yearling steers, 39 Friesians on an 18-month beef production system (group 1) and 38 Hereford × Friesians on a 20-month beef production system (group 2), were weighed, blood sampled and then half of them were implanted subcutaneously with 300 mg trenbolone acetate and 30 mg hexoestrol. All steers were then weighed and blood sampled at 1-month intervals for a further 3 (group 1) or 4 (group 2) months. Serum was assayed for prolactin, insulin, growth hormone, glucose and blood urea nitrogen concentrations. Steroid treatment increased daily live-weight gain by 28 to 37% over the experimental period and the proportional response appeared to be correlated with the plane of nutrition. Neither prolactin nor glucose concentrations were affected by the treatment. However, in both groups 1 and 2, growth hormone concentrations were significantly higher in implanted steers, whilst urea-nitrogen concentrations were significantly lower. Insulin concentrations were consistently, although not significantly, lower in implanted than in control steers.