Utilização estratégica de insulina durante protocolos de sincronização da ovulação em bovinos

Abstract

The animal reproduction is one of the major important factors in cattle and directly affects the efficiency and profitability of the system. The increase in blood concentrations of NEFA and BHBA, while IGF-I concentrations, glucose and insulin are low, affects the growth, maturation and ovulation of the dominant follicle. The overall aim was to evaluate the use of insulin in synchronization protocols of ovulation in cattle. Two studies were conducted, the first to evaluate the effect of the insulin on the growth of the dominant follicle, production of estradiol and progesterone. Twenty-one primiparous holstein cows were used, averaging 70 days in milk, maintained in a semi-extensive system. The animals were submitted to a fixed-time artificial insemination protocol which consisted of the application of 2 mg of estradiol benzoate and insertion of a slow release of progesterone device on day 0. Application of 12,5 mg of dinoprost on day 8 and 5 mg of GnRH on day 9 of the protocol. On day 8, the animals were divided into control group (GC, n 9) and insulin group (GI, n 12), which received an application of 0,25 IU / kg of insulin. The second study was divided into two experiments to evaluate the effect of the insulin on the growth of the dominant follicle, P4 and pregnancy rate in beef cows. In experiment 1, 215 Bos taurus cows were subjected to a fixed-time artificial insemination protocol which consisted of the application of 2 mg of estradiol benzoate and insertion of a slow release of progesterone device on day 0. On day 9 progesterone removal device, the application of 0,5 mg of estradiol cypionate, 12,5 mg of dinoprost and division of animals GC 109 and GI 106, which received application of 0,25 IU / kg insulin. In experiment 2, they were used 85 cows Bos taurus, for an embryo transfer protocol. On day 0 was made the application of 2 mg of estradiol benzoate and insertion of a slow release of progesterone device. On day 5 of the protocol, it proceeded with the application of 0.150 mg of d-Coprostenol. On the 8th day of removal progesterone application of 20 mg of porcine pituitary folltropin and division of animals in GC 49 and GI 36 which received application of 0,25 IU / kg insulin in the 9th day was applied 1 mg of estradiol benzoate and 17 of the protocol proceeded with embryo transfer. In the first study, the application of insulin did not increase the diameter of the dominant follicle, estradiol production, luteal area and production of P4, but the animals in the control group showed a numerical reduction of luteal area and P4 levels of the first to the second evaluation. In the second study, the application of insulin did not increase the diameter of the dominant follicle production P4, and pregnancy rate.