Factors affecting sex ratio of calves born after embryo transfer [Spanish]

摘要

The objective of this study was to determine sex ratio in offspring from embryo transfer and to identify factors influencing this proportion. Data of a total of 2226 calves born from 1989 to 1993 at the CEMEGEN LICONSA breeding center, State of Mexico, including 1004 calves born by artificial insemination (AI) and 1222 from embryo transfer (ET) was analyzed. A chi-square test was used to compare sex ratio of calves born by AI or ET. In addition, a logarithmic linear model was used to estimate the effect of season, type of embryo (fresh or frozen), grade and quality of the embryo, donor/recipient synchrony and genetic group on sex ratio. There was a greater proportion of males (pless than or equal to0.01) derived from ET (55.4%) than from AI (49.3%). The proportion of males born from embryos collected during the summer (61.4%) was greater (pless than or equal to0.05) than in spring (51.0%). The other variables did not modify (p>0.05) the expected sex ratio.