Influence of bovine recombinant somatotropin (rBST) on metabolic parameters, hormones and semen quality of bulls

The growth hormone (GH) have as main function improve proliferation and cellular development, but also participates of processes related to the immune system and reproductive function. The effect of GH is exerted by the IGF-I (insulin-like growth factor I), that is a hormone polypeptidic mitotic secreted by all cells that carry through mitosis. Since the development of the recombinant form of the bovine recombinant somatotropin (rBST) various studies have been developed on milk and meat production in farm animals. The objective of this study was to evaluate the effect of rBST on metabolic markers of energetic, protein, mineral and hepatic metabolism, as well as, to evaluate its effect on concentrations of IGF-I, insulin and quality parameters semen in bulls. This study was carried in central of artificial insemination ABS/PECPLAN using 20 bulls of european breeds. These animals were divided in two groups, a group that received a placebo application (NaCl, 0.9%) and another that received rBST (Lactotropin®/Elanco Animal Health). Five blood collections for evaluation of metabolic and hormonal markers and 6 semen collections with posterior freezing for the accomplishment of the corresponding semen evaluations. There was no effect of rBST (P > 0,05) in metabolic markers, except in the concentration of gamma- glutamyltransferase (GGT), that increased in the group that received rBST (P 0,05). In relation to the semen evaluations, there were no differences observed (P > 0,05) in motility and morphology evaluated in the period before freezing. In after freezing evaluations, being that motility, morphology, integrity of plasmatic membrane by fluorescent sounding leads and the hiposmotic test, differences have been observed (P 0,05) efeito do rBST nas avaliações dos marcadores metabólicos, exceto nas concentrações da enzima hepática gama - glutamiltransferase (GGT), que foi mais elevada no grupo que recebeu o rBST (P 0,05). Em relação às avaliações de sêmen, não foram observadas diferenças entre os dois grupos (P > 0,05) na motilidade e morfologia espermática avaliadas no período pré-congelamento. Nas avaliações pós-congelamento que incluíam a motilidade, morfologia, integridade de membrana plasmática por sondas fluorescentes e pelo teste hiposmótico foram observadas diferenças (P < 0,05) entre os grupos, sendo demonstrado melhores índices no grupo que recebeu o tratamento com rBST. Desta forma pode-se observar que o rBST, além de elevar o níveis de IGF-I, influenciou positivamente as características seminais avaliadas no pós-congelamento sem que tivesse ocasionado desequilíbrio no metabolismo dos animais tratados, já que as concentrações dos marcadores metabólicos avaliados estavam de acordo com os padrões fisiológicos para a espécie bovina