Pregnancy Rates Bovine Recipients Inovulated with in Vitro Produced (IVP) Embryos in The Legal Amazon

Abstract

The aim of the work was to evaluate transfer efficiency in in vitro produced (IVP) bovine embryos, at different stages of development, through pregnancy rates of inovulated cows, in the Amazon Region. 5403 embryo transfers conducted during dry and rain season, with IVP embryos, at different stages of development, and recipients with different corpora lutea types, were evaluated. The oocytes were obtained from zebu cows, through vaginal aspiration by ultrasonography. The oocytes were matured, fertilized, and cultured in vitro. The embryos were transferred to cyclic crossbred cows, at the stages of morula (MO), early blastocyst (BI), blastocyst (BL), expanded blastocyst (BX), hatching blastocyst (BN) and hatched blastocyst (EB). The corpora lutea were classified by ultrasonography into protruded and included. Pregnancy was achieved in 34.30% (1855) of the animals; with significantly higher pregnancy rates for embryos at BX (38.2%) stage. The embryos at BN and BX stages were similar; however MO, BI and BL stages did not differ statistically (P>0.05). The analysis showed no correlation between corpus luteum size, or type, and the development of IVP embryos inovulated at different stages. Pregnancy rates did not differ (P > 0.05) for embryo transfers performed during dry (33.7%) or rainy (35.7%) season. Pregnancy outcomes obtained after transfer of IVP embryos, from the Amazon Region, were similar to studies in other regions and were not influenced by seasons.