Periódicos Brasileiros em Medicina Veterinária e Zootecnia

p. 217-224

Sex-sorted sperm for artificial in semination and embryo transfer programs in cattle

Sá Filho, M. FNichi, MSoares, J. GVieira, L. MMelo, L. FOjeda, ACampos Filho, E. PGameiro, A. HSartori, RBaruselli, P. S

The selection of offspring from the desired sex can be one of the determining factors to increase the genetic progress and farmer ́s profitability in either beef or dairy cattle. In fact, the use of sex-sorted sperm has been applied worldwide combined with artificial insemination (AI) upon estrus detection in heifers. Additionally, several researches have been performed aiming to investigate the use of sex-sorted sperm during timed AI (TAI) programs and for insemination of superstimulated donors for in vivo embryo programs. Pregnancy per AI (P/AI) of cyclic heifers inseminated in estrus with sex-sorted sperm has been reported to be approximately 75 to 80% of the P/AI of heifers inseminated with non-sorted sperm. Insemination of superstimulated cows with sex-sorted sperm has been reported to reduce the production of viable embryos. Recently, however, it has been demonstrated that P/AI and embryo production per flushing resulting from AI with sex-sorted sperm may be improved when the time of AI is postponed in relation to the time of AI with non-sorted sperm. The P/AI of non stimulated females and fertilization rates and number of embryos recovered from superstimulated females were increased when AI occurred between 16 and 24 h after the onset of estrus (i.e. 6 to 14 h before ovulation). Nonetheless, despite the improvements achieved in the last decade, there is still a significant individual variability in fertility among bulls that have their sperm se x-sorted. It is critical that the pre-determination of the sire fertility is a paramount when sex-sorted sperm is utilized in commercial AI and ET programs. Thus, the aim of this review is to discuss the main concepts related to the use of sex-sorted sperm in TAI and ET programs, addressing some strategies to increase the efficiency of the technique. (AU)

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