Post-ejaculation incubation of semen as a method to alter the sex ratio of offspring obtained by artificial insemination in rabbits

Abstract

In mammals, the sex ratio under natural conditions is 50% female and 50% male. However, this ratio can be altered by some methods. The application of warmth (42ºC) to the scrotum has an effect on the functioning of spermatozoa within the epididymis and modifies the sex ratio of offspring obtained through natural mating. The aim of this study was to determine the effect of post-ejaculation incubation temperature (42ºC or 30ºC) on the sex ratio of offspring obtained by artificial insemination. Each ejaculate was diluted and divided into two equal aliquots (0.5mL), one of which was incubated at 42ºC and the other at 37ºC for 30min. The sperm motility and viability at 42ºC was 87.3% and 89.4%, and at 37ºC, 88.2 and 75.5%, respectively. When artificial insemination was performed using semen incubated at 42ºC and 37ºC, 6.38, and 7.83 connies were born per litter, respectively. The sex ratio of offspring when sperm was incubated at 42ºC was 56.2% females and 43.7% males, while for semen incubated at 37ºC it was 52.6% females and 47.4% males. In conclusion, incubation of semen post ejaculation at 42ºC for 30 min could be used to favor the birth of female offspring through artificial insemination.