Effects of bovine somatotropin injection on serum concentrations of progesterone in non-lactating dairy cows

Autor(es)

Aboin, A. C. ^[1] ; Cooke, R. F. ^[2] ; Vieira, F. V. R. ^[1] ; Leiva, T. ^[1] ; Vasconcelos, J. L. M. ^[1]

Afiliação do(s) autor(es)

^[1] Fac Med Vet & Zootecnia UNESP, Dept Prod Anim, BR-18618000 Botucatu, SP - Brazil

^[2] Oregon State Univ, Eastern Oregon Agr Res Ctr, Burns, OR - USA

• Tipo de documento: Artigo Científico
• Fonte: LIVESTOCK SCIENCE; v. 154, n. 1-3, p. 240-245, JUN 2013.
• Citações Web of Science: 4

Resumo

The objective of this experiment was to evaluate the effects of bovine somatotropin administration on serum concentrations of glucose, insulin, NEFA, IGF-I, and progesterone (P4) in ovariectomized non-lactating dairy cows receiving exogenous P4, as a model to estimate treatment effects on hepatic P4 degradation. Ten non-lactating, non-pregnant, and ovariectomized Gir x Holstein cows were assigned to the experiment (d -14 to 27). On d 0, cows were ranked by BW and BCS, and randomly assigned to one of two treatments: (1) bovine somatotropin (BST; n=5) or (2) saline control (control; n=5). Cows assigned to the BST treatment were administered s.c. injections containing 500 mg of sometribove zinc on d 0, 9, and 18 of the experiment, whereas control cows concurrently received a 10-mL s.c. injection of 0.9% saline. On d -2, cows were inserted with an intravaginal releasing device containing 1.9 g of P4, which remained in the cows until the end the experiment (d 27). Cow BW and BCS were assessed on d -14, 0, and 27. Blood samples were collected daily from d 0 to d 27, at 0 (immediately before), I, and 2 h relative to concentrate feeding for determination of serum glucose, insulin, NEFA, P4, and IGF-I concentrations. Concentrations of glucose, NEFA, and insulin obtained prior to feeding (0 h) were used to determine pre-prandial revised quantitative insulin sensitivity check index (RQUICKI). No treatment effects were detected for BW (P=0.72) and BCS change (P=0.79) during the experiment. Beginning on d 2 of the experiment, BST cows had greater (P <= 0.01) serum IGF-I concentrations compared with control cohorts (treatment x day interaction; P<0.01). Cows receiving BST had greater (P <= 0.05) insulin concentrations compared with control cohorts from d 8 to d 11, d 16 and 17, as well as from d 19 to d 21 of the experiment (treatment x day interaction; P < 0.01). Cows receiving BST had greater (P <= 0.01) mean glucose and NEFA concentrations, as well as reduced (P < 0.01) mean RQUICKI during the experiment compared with control cohorts. No treatment effects, however, were detected (P=0.73) for serum P4 concentrations. In conclusion, results from this experiment indicate that hepatic P4 catabolism is not directly regulated by circulating IGF-I, whereas BST administration decreases insulin sensitivity in non-lactating dairy cows in adequate nutritional status. (C) 2013 Elsevier B.V. All rights reserved. (AU)

• Processo FAPESP: 11/10308-7 - Efeito da injeção de bST nas concentrações séricas de glicose, insulina, IGF-1 e progesterona em vacas secas e ovariectomizadas em diferentes balanços energéticos
• Beneficiário: José Luiz Moraes Vasconcelos
• Modalidade de apoio: Auxílio à Pesquisa - Regular