Effect of ejaculate, bull, and a double swim-up sperm processing method on sperm sex ratio

Abstract

Offspring gender preselection has applications of considerable economic, health and ecological interest. In this study we analysed modifications of the percentages of spermatozoa bearing Y and X chromosomes when semen samples are submitted to a double swim-up technique as a possible method for producing embryos of known sex with in vitro fertilisation protocols. As an initial experiment to provide accurate evaluation of the method we determined the possible incidence of natural deviations in the primary sex ratio between bulls or ejaculates, analysing the percentage of Y-chromosome DNA bearing spermatozoa (%Y-CDBS) with a polymerase chain reaction (PCR) amplification of X- and Y-specific fragments. Ejaculates were tested by direct semiquantitative PCR sexing and by sexing blastocysts produced in vitro with these spermatozoa. Bulls and ejaculates did not have any effect on the %Y-CDBS or on the sex ratio of embryos produced in vitro using these ejaculates. However, our double swim-up sperm preparation method produced differences in %Y-CDBS in some of the sperm fractions, suggesting that there are intrinsic differences in capacitation of X- and Y-bearing spermatozoa that might be used to produce embryos of the desired sex with in vitro fertilisation.

Male pygmy hippopotamus influence offspring sex ratio

“…Most available studies, conducted on samples from boar10, cattle1011121314 or humans151617, used inaccurate evaluation techniques such as fluorescence staining of the F-body or PCR amplification on pooled semen samples. Correlation between the ratio in the ejaculate and the birth sex ratio was found in those studies that made the comparison121617.…”

Variation among Beef Bulls in the Ratio of X- to Y-Chromosome Bearing Spermatozoa

“…Chandler et al [5] found acrosomal integrity (% intact acrosomes) after 3 h incubation at 37˚C post-thaw was positively correlated the percentage of Y-bearing sperm in semen and percentage of bull calves at birth. A study utilizing a double swim-up procedure with bull semen reported that the fraction of Y-bearing sperm is increased in some ejaculates following the double swim-up which was attributed to differences in capacitation of X-and Y-bearing sperm [19].…”

Factors Affecting the Secondary Sex Ratio of the Iranian Raeini Goats

“…However, the sex ratio in the lambs of the two breeds of Polwarth and Corriedale did not have a significant deviation with the equal ratio [17]. Theoretical mechanisms deviatied the sex ratio of the offspring included the differences in the viability of the sperm, general conditions of the genital system (such as cervical mucus status, nutritional status and vagina pH during fertilization), intrinsic physiological differences and embryo selection or abortion [18].…”