caa a22 4500 386320837 CHVBK 20180307111626.0 cr unu---uuuuu 161130e198808 xx s 000 0 eng 10.1017/S0003356100037004 doi S0003356100037004 pii (NATIONALLICENCE)cambridge-10.1017/S0003356100037004 Steen R. W. J. Agricultural Research Institute of Northern Ireland, Hillsborough, Co. Down BT26 2DR The effect of implantation with hormonal growth promoters on the response in the performance of beef cattle to protein supplementation of a silage-based diet [Elektronische Daten] [R. W. J. Steen] An experiment has been carried out to examine the effects of implantation with hormonal growth promoters on the response in the performance of castrated male cattle (steers) to protein supplementation of a silage-based diet. The treatments consisted of grass silage offered ad libitum and supplemented with 2·7 kg per head daily of either a low protein (LP, 114 g crude protein per kg dry matter (DM)) or a high protein (HP, 206 g crude protein per kg DM) concentrate. Half of the animals, given each of the two concentrates were implanted with 20 mg oestradiol plus 200 mg progesterone and 300 mg trenbolone acetate at the beginning of the experiment and after 77 days, while the remainder of the animals received no implant, giving four treatments in a 2 × 2 factorial design. Sixty-four British Friesian and Simmental cross steers which were initially 426 (s.e. 3·5) kg live weight were used. The treatments were imposed for 157 days. The silage used was well preserved and of high digestibility. For LP and HP concentrates given to non-implanted animals and LP and HP given to implanted animals respectively silage DM intakes were 5·7, 5·8, 6·3 and 6·6 (s.e. 0·18) kg/day; live-weight gains 0·96, 0·92, 1·22 and 1·33 (s.e. 0·045) kg/day; carcass gains 0·58, 0·53, 0·78 and 0·81 (s.e. 0·024) kg/day; carcass subcutaneous fat depth 6·0, 6·5, 5·8 and 5·5 (s.e. 0·35) mm; areas of m. longissimus dorsi 69·1, 58·5, 69·6 and 74·7 (s.e. 1·91) cm2 and marbling scores 3·0, 3·6, 3·3 and 3·1 (s.e. 0·25). It is concluded that protein supplementation of well preserved grass silage produced a marginal increase in the performance of implanted finishing steers but did not affect carcass fatness. With non-implanted steers protein supplementation produced a marginal depression in performance and increased carcass fatness. Copyright © British Society of Animal Science 1988 Animal Production Cambridge University Press 47/1(1988-08), 21-28 0003-3561 47:1<21 1988 47 ASC https://doi.org/10.1017/S0003356100037004 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1017/S0003356100037004 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Steen R. W. J. Agricultural Research Institute of Northern Ireland, Hillsborough, Co. Down BT26 2DR NATIONALLICENCE 773 0- Animal Production Cambridge University Press 47/1(1988-08), 21-28 0003-3561 47:1<21 1988 47 ASC CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge