Effect of trenbolone acetate combined with oestradiol -17β on the response of steers to changes in dietary protein

Abstract

Hormonal anabolic compounds are used in certain countries to improve the efficiency of meat production from ruminant animals. The combination of trenbolone acetate (TBA) and oestradiol-17/? (OE 2 ) has been shown to be particularly effective in stimulating growth in cattle (e.g. Galbraith & Topps, 1981). These improvements in growth have been associated with increases in nitrogen retention and changes in protein metabolism within the animal. The present study therefore investigated the effect of implantation with TBA + OE 2 on the growth and metabolic response of growing steers to alterations in protein nutrition. METHODSTwelve British Friesian steers aged approximately 15 months were housed in individual stalls and allowed 6 weeks to adapt to experimental conditions. The animals were then paired according to live weight and one of each pair allocated to be implanted subcutaneously on the upper surface of the ear flap with 140 mg TBA + 20mg OE 2 ('Revalor', Hoechst, U.K. Ltd). Their initial mean live weight (±S.E.) was 439 ±6-9 kg. The steers were offered diets containing an estimated 107 MJ metabolizable energy per day and differing in rumen degradable (RDP) and undegradable (UDP) protein as follows: day 0-28 (period A), 0-86 and 0-18; day 29-56 (period B) 0-99 and 0-51; day 57-84 (period C) 0-86 and 0-18. The diets were based on grass silage, bruised barley and sugar-beet pulp in the ratio in the dry matter of 1 -0:0-65:0-65 respectively (periods A and C). The diet was supplemented in period B with a mixture (ratio 1:1) of soya-bean meal and white fish meal. The rumen degradability of this mixture was determined by Dacron bag technique utilizing a 12 h incubation in the rumen of a fistulated cow. The degradability coefficients of the other dietary components were estimated from Scottish

The effect of oestradiol-17 β implantation on the response in voluntary intake, live-weight gain and body composition, to fishmeal supplementation of silage offered to growing calves

“…Review articles by Trenkle (1976) and Galbraith & Topps (1981) on the effect of hormones on growth concluded that there were insufficient data to suggest the existence of an interaction between dietary protein and the response to oestrogens. However, more recently, Galbraith et al (1983) reported a tendency towards an interaction between protein level and implantation, with fattening cattle implanted with trenbolone acetate combined with oestradiol-17/?. However, the protein treatments lasted for only 28 days and the difference between treatments was not significant.…”