Efeito na produção in vitro de embriões bovinos de diferentes concentrações de Beta-NGF no meio de maturação ovocitária

Abstract

One of the most used biotechniques in recent years, applied to animal reproduction, is in vitro embryo production (IVP), a biotechnology that has played a prominent role in the evolution of cattle breeding efficiency. This is mainly due to the possibility of increasing the production of calves per genetically superior cow. However, it is a high-cost technique and the use of oocytes is inefficient. In addition, a positive correlation was also verified between the amount of Beta-NGF in sperm and cleavage and blastocyst rates in PIVE, which indicates possible action during early embryonic development. Recently, it was verified that the addition of 100 ng/mL in the oocyte maturation medium increases the efficiency of PIVE in cattle. The present work aimed to evaluate the effect on the in vitro production of bovine embryos of two different concentrations of β-NGF in the oocyte maturation medium. For this, PIVEs were performed, in which the oocytes were obtained from follicular aspiration, carried out in the laboratory, from ovaries collected in a commercial slaughterhouse in Araguari-MG. Frozen semen from a single bull from a semen processing center with proven fertility was used for in vitro embryo production. In all routines, drops of maturation medium were used without protein supplementation and with β-NGF supplementation at concentrations of 100 ng/mL and 500 ng/mL. The cleavage rate was evaluated 48 hours after in vitro fertilization, by evaluating the structures that had two or more cells. Seven days after fertilization, the rate of embryonic development was evaluated by counting the structures that initiated cleavage and reached the blastocyst stage. The cleavage rate was different between all treatments, being higher with 100 ng/mL and lower with 500 ng/mL. Embryonic development rates showed no difference. The efficiency of PIVEs was also higher with 100 ng/mL and do not show any difference between the control and 500 ng/mL. It can be concluded that the supplementation of the oocyte maturation medium with 100 ng/mL of NGF improves oocyte maturation in vitro, improving the efficiency of PIVE. Supplementation with 500 ng/mL, on the other hand, causes a negative effect, probably cytotoxic, and, consequently, is not indicated in PIVE routines.