PREGNANCY RATES OF BOVINE EMBRYO TRANSFER RECIPIENTS IN THE TROPICS

Abstract

This study, carried out under field conditions in Yucatán, México, was carried out to investigate the effect of some factors on pregnancy rates in bovine embryo transfer recipients. One hundred and thirteen nonsurgical embryo transfers were made in cows and heifers of three genotypes (B. taurus, B. indicus and crossbreeds). Pregnancy was determined 45 days after transfer by rectal palpation. Factors studied included recipient genotype, body condition, reproductive status, estrus behavior, and synchronization of estrus between donor and recipient. Statistical analysis was performed by the Chi-square method. Pregnancy rate from recipients observed in estrus was higher (p 0.05) by recipient genotype, body condition, reproductive status, nor synchronization of estrus. Pregnancy rate in crossbreeds was 50.0 %, 48.7 % in B. taurus and 47.6 % in B. indicus. Pregnancy rate was 58.8 % in cows and 50.0 % in heifers. Pregnancy rate in recipients from a body condition score of 3 to 4.5 was similar to those scoring 5.0 to 7.5 (52.7 % and 54 %, respectively). Pregnancy rates related to synchronization of estrus were 50.0 % (>-12 h), 65.8 % (0±12 h) and 53.8 % (>+12 h). Therefore, in this study there were no significant effects of the factors studied on pregnancy rates.