289 EFFECTS OF YEAR PERIOD, TECHNICAL TEAM, AND BREED ON THE PREGNANCY RATES AFTER TRANSFER OF IVF BOVINE EMBRYOS IN THE SOUTHERN REGION OF RIO DE JANEIRO

Abstract

The aim of the work was to study the effects of year period, technical team, breed, beef cattle and dairy cattle on the pregnancy rates in fresh embryos used in bovine transfer of IVF programs. The study was carried out at the fertilization laboratory In Vitro Nyltta Britto de Carvalho, in partnership with In Vitro Brazil, located at the Boa Vista farm, Barra do Pirai, during August 2007 to September 2008, seeking subsidies to improve the use of the technique in the field. During that period, aspirations and inovulations in 3 different periods I (August to December), II (January to April), and III (May to September) were carried out. The jobs were accomplished by 9 technical teams (A, B, C, D, E, F, G, H, and I) rendering services to the laboratory, by working with 2 beef breeds (Brahman and Nelore) and 3 dairy breeds (Gir, Girolando, and Holstein). The different breed receivers were synchronized, and in general, from 6 to 8 days after heat, they received embryo transfer, the cervical way, under low epidural anesthesia, where each female received 1 fresh embryo of IVF. All cows were submitted to gestation diagnosis by rectal palpation and ultrasonography, in general, 42 days after embryo transfer. The numbers of embryo transferred and pregnancy rates were submitted to the chi-square test, which presented significant differences (P < 0.05). There were pregnancy rates of 36.25%^a (n = 960), 39.83%^a (n = 1180), and 32.59%^b (n = 919) in the I, II, and III periods, respectively. Among the 9 technical teams, there were verified pregnancy rates (%) of 33.51^d (n = 1313), 30.30^d (n = 330), 35.00^cd (n = 405), 39.24^cd (n = 1060), 59.25^a (n = 7), 33.33^d (n = 24), 53.57^bc (n = 28), 43.31^c (n = 157), and 58.33^ab (n = 12) for A, B, C, D, E, F, G, H, and I teams, respectively. Among breeds there were rates (%) of 36.89^ab (n = 412), 34.68^b (n = 1286), 35.13^ab (n = 74), 38.94^a (n = 1140), and 37.80^ab (n = 82) for Brahman, Nelore, Gir, Girolando, and Holstein, respectively. In the study, pregnancy rates (%) of 35.21^b (n = 1698) in beef cattle and 38.65^a (n = 1296) in dairy cattle were observed. The differences in pregnancy rates with respect to the evaluated factors, may be explained by individual, breed, and nutritional variations of the animals. There are few data in the literature with results on the embryo transfer use of IVF bovine under field conditions.