Growth and carcass composition of pre-pubertal dairy heifers treated with bovine growth hormone

Abstract

The effects of long-term administration of exogenous growth hormone (GH) on growth and carcass composition of pasture-fed, pre-pubertal dairy heifers were examined. Purified bovine GH (specific activity, 0·78 i.u. per mg) was administered daily for 21 weeks (0·6 mg GH per kg M0·75) to one member of each of 12 sets of twins. GH administration resulted in a significantly higher growth rate (0·58 kg/ day) compared with the control group (0·54 kg/day) and produced a heavier carcass (75·6 kg v. 69·5 kg). However, this production gain did not persist when GH treatment ceased. Plasma metabolite concentrations and carcass composition were not affected by GH treatment. GH tended to increase slightly the voluntary intake of freshly cut herbage dry matter (3·5 kg/day v. 3·7 kg/day; P < 0·05), but had no effect on food conversion efficiency. Serum somatomedin levels were not significantly increased by GH during week 13 of treatment. This experiment indicates that pre-pubertal heifers chronically treated with GH will increase their food intake to sustain an increased rate of growth. However, the production gains made over the treatment period were transient and within 5 weeks of the cessation of GH treatment there was no difference in the live weight of the two groups.

Responses of Lactating Ewes to Exogenous Growth Hormone: Short- and Long-term Effects on Productivity and Tissue Utilization of Key Metabolites

“…1985) and cattle (Eisemann et at. 1986;Sandles and Peel 1987) injected with GH. In each of these studies increased liveweight gain was associated with decreased carcass fat.…”

“…None-the-less, the results raise the possibility that maintenance of high plasma GH is necessary to sustain the production increases. In this connection, Peel et al (1985) and Sandles and Peel (1987) reported that increased milk production from dairy cows and increased growth of dairy heifers were not sustained after withdrawal of GH treatment.…”

“…The preparation of GH was extracted from bovine pituitary glands, assayed for impurities and assessed for its biological activity (1'6 U mg-I ) as outlined previously by Sandles and Peel (1987).…”

Effect of virginiamycin and bovine somatotropin on growth, nutrient conversion and blood parameter in young female calves

“…Les (Ilan et al, 1981;Marounek et al, 1989), virginiamycin (Daenicke, 1988;Skrivanova and Marounek, 1993;Skrivanova et al, 1994), lasalocid (Anderson et al, 1988), avoparcin (Moughan et al, 1989) and aureomycin (Brown et al, 1960) Brumby (1959). Similar results were obtained by Sandles and Peel (1987) in heifers treated with 600 pg bST.kg-l.da!rl. Recombinant bST (25-100 p g .kg-1 .day-1 ) increased the average daily gain of 6-weekold female veal calves by 7.1-10.8% (Kirchgessner et al, 1987 increased in the bST + V group at 10 weeks of age (P < 0.05).…”

Peso vivo final, ganho de peso, características de carcaça e concentrações plasmáticas de IGF-I e hormônios tireoideanos de bezerros mestiços Angus-Nelore recebendo somatotropina bovina recombinante (rbST) até a desmama

“…O aumento da concentração plasmática de IGF-I verificado nos animais que receberam rbST (34,1% em relação ao controle) corrobora a informação de que a administração exógena de somatotropina resulta em elevação dos níveis plasmáticos (Vernon, 1989), como também constatado por Sandles & Peel (1987), em novilhas; Dalke et al (1992) e Tripp et al (1998), em novilhos confinados; Vestergaard et al (1995), em bezerras; e McLaughlin et al (1993), em ovinos. Os principais efeitos estimulatórios de crescimento do GH são mediados pelas somatomedinas, principalmente IGF-I, sintetizado no fígado e em outros órgãos, podendo atuar tanto no próprio órgão em que foi sintetizado (ação autócrina) ou mesmo em diferentes tecidos (ação parácrina) (Coutinho, 1996).…”