Blood leptin, insulin and glucose concentrations in hair sheep raised in a tropical climate

The aims of this study were to determine the effects of body condition score (BCS), breed and dietary supplementation on the concentrations of leptin, insulin and glucose found in the blood obtained from hair sheep during the breeding season. A further aim was to investigate the possible association of fertility and prolificacy with these blood metabolites, BCS and body weight (BW). All ewes were grazed in paddocks with ad libitum access to mineral salts and water. A total of 96 ewes were divided into two groups according to breed and treatment: Santa Ines (supplemented or unsupplemented) (24 x 24) and Morada Nova (supplemented or unsupplemented) (24 x 24). Blood samples, and BW and BCS information were collected during the breeding season. The statistical analyses were performed using the program PROC GLM from the SAS software. The leptin concentrations in hair sheep raised in a tropical climate were low. Little effect of breed, treatment or sample collection was found for blood insulin concentrations (p <0.05), although the values were higher in the supplemented groups from both breeds. Significant differences were observed in glucose concentrations between the breeds in the same sample collections, with the higher concentrations being found in the Santa Ines sheep (p < 0.05). The BCS for ewes that were not pregnant showed the highest correlation with leptin, insulin and glucose concentrations (r=0.53, 0.52 and 0.43, respectively). In the Morada Nova supplemented sheep (prolificacy: 1.45), there were verified correlations between BCS and BW, BCS and insulin concentration, and also between insulin and leptin concentrations. The present study shows that the Morada Nova breed has a higher reproductive efficiency than the Santa Ines breed. In conclusion, leptin was present in low concentrations in hair sheep and did not influence the reproductive processes in these animals. The dietary supplementation positively affected blood leptin, insulin and glucose concentrations in these breeds of hair sheep, but there was no major effect on the reproductive processes. (C) 2013 Elsevier B.V. All rights reserved.