Relação da concentração de insulina, IGF-1 e Leptina no colostro de fêmeas bovinas de corte com metabólitos plasmáticos e desempenho de bezerros

Abstract

Colostrum is primarily known for its importance in the transfer of passive immunity, however its function goes far beyond this. Colostrum is closely involved with intestinal development providing different nutrients and this development directly reflects on the animal's production of meat or milk. The presence of growth factors, insulin and other compounds promote cell growth and differentiation in addition to gastrointestinal development, these growth factors present in colostrum are responsible for stimulating mucosal growth, enzymes, increased villi size and glucose uptake. The aim of the study was to understand the role of insulin, IGF-1 and leptin in colostrum in correlation with plasma metabolites in calves and the relationship of their concentration with development and weight gain of these animals raised under the same conditions. Twenty crossbred beef cattle were used, 12 primiparous (G1) and 8 multiparous (G2) and their 20 calves. The animals were kept in an extensive system under continuous grazing in a ryegrass (Lolium multiflorum) paddock during calving and sampling period. For the evaluation of blood metabolites, single blood samples were collected from the females for glucose, hematocrit, protein, cholesterol, triglycerides, albumin and insulin, soon after calving (T0) and from calves at birth (T0), at 24 (T24), 48 (T48) and 168 (T168) hours of life for glucose, hematocrit, protein, GGT, cholesterol, triglycerides, albumin, insulin, IGF-1 and leptin. For analysis of fat, lactose, brix, protein, insulin, leptin and IGF-1 from colostrum, this was collected before the first feeding. For performance evaluation, calves were weighed at birth (0) and every 30 days until 6 months of age. There were no differences between the colostrum composition of multiparous and primiparous cows (P>0.05), colostrum insulin was negatively correlated with colostral lactose and positively correlated with protein (P<0.05) and brix (P<0. 05). There were no differences in blood parameters between multiparous and primiparous (P>0.05). Among calves, there were differences in cholesterol concentration at T24 (P<0.05), GGT at T24 (P<0.05), triglycerides at T48 (P<0.05) and there was also a difference in insulin concentrations at T48 (P<0.05). Regarding the performance, the calves showed a difference only in the sixth weighing (P<0.05). There was no correlation between insulin, IGF-1 and colostral leptin and weight gain in calves (P>0.05). Insulin and IGF-1 present in the colostrum of the animals studied did not influence the final performance in weaning calves and, despite the high concentration of insulin in the colostrum, there are no changes in the biochemical parameters studied, except for triglycerides, suggesting that there is no absorption of these. There were no differences in colostrum composition between primiparous and multiparous raised in extensive conditions, the bioactive compounds did not influence the performance of calves and calves raised in the same conditions showed similar metabolism in the first week of life. More tissue-level studies are needed to understand the presence of high concentrations of insulin and IGF-1 in bovine colostrum.