Influência da concentração de insulina no colostro sobre as concentrações de IGF-I, leptina e perfil metabólico em ovinos

Abstract

Sheep farming faces major challenges, such as the high mortality rates of lambs in the first few days of life, resulting in low productivity. Several factors directly affect the survival of lambs, including the failure to ingest colostrum. Colostrum is a rich food and contains various bioactives, such as insulin, which influences intestinal development and increases energy metabolism. In addition, growth factors or hormones affect the development of the gastrointestinal tract of neonates in different species. The aim of this study was to evaluate the concentrations of inulin, leptin and IGF-I in primiparous and multiparous sheep and their correlation with the metabolic profile and performance of the lambs. We used 22 females raised in a semi-intensive system, of the Ile de France and Texel breeds, 12 primiparous (GP) and 10 multiparous (GM) from the same breeding season and their 27 lambs. Blood samples were taken from the lambs by external venojugular puncture shortly after birth (H0), 12 (H12), 24 (H24), 48 (H48) hours after birth and on the seventh day of life (H168). In parturient females, the samples were collected only after birth (H0), when colostrum was collected by hand milking into sterile vials. The blood samples were analyzed for glycemia, plasma protein, cholesterol and triglyceride. Insulin, IGF-I and leptin from blood and colostrum were analyzed using the enzyme-linked immunosorbent assay (ELISA) test. Weight samples were taken at birth, seven, 15, 30 and 45 days of age (BW, P7, P15, P30, P45, respectively) to monitor the lambs' development. Statistical analyses were carried out using the GraphPad Prism 6 program. In colostrum, insulin and IGF-I concentrations were similar, with a difference (p<0.05) only in leptin, which was higher in GP. The biochemical analyses of the mothers (GP and GM) were similar, except for the cholesterol levels (p<0.05), with higher values in the GP. Lambs from multiparous dams showed higher insulin values at H0 (p<0.05). Leptin values were higher in lambs from multiparous dams at H0 and H12, with a reversal at H24, showing significant differences at all the times evaluated (p<0.05). IGF-I values were similar, as were the biochemical variables of these lambs. For average weight gain, there was a significant difference (p<0.05) in all periods. The concentrations of insulin, leptin and IGF-I had no correlation with higher or lower values of the metabolites studied. More research is needed to understand how colostrum and other factors affect the development of lambs and their future growth.