A field study on the reproductive efficiency of sex-sorted semen in Holstein heifers

Sex-sorted semen can increase the profitability of dairy cattle by producing offspring of the desired sex. The objective of the present study was to compare conception rate, stillbirth, calving difficulty and sex ratios from sexed and conventional semen in a commercial dairy herd in Isfahan province, Iran. Data were collected from April 2009 until December 2015 on 13,343 inseminations in 8,011 nulliparous Holstein heifers. Based on the proportion of female calves, purity of the sexed sperm was 86.45%, indicating that sexed semen technology was effective in producing heifers. However, sex ratio at birth from conventional semen was 49.05% female. Empirical conception rate in heifers was 42.65% for sexed and 54.85% for conventional semen (P < 0.05). Based on the obtained results, approximately 77.75% of conception rates in heifers were compromised by the sperm sorting procedure. No significant difference was observed for stillbirth due to sexed vs. conventional semen (P > 0.05). The results showed that the higher percentage of female calves in the sexed semen heifers was accompanied by lower risk of dystocia. Despite the higher cost and reduced conception rate, sexed semen can be recommended for insemination of heifers as its use is associated with lower rate of dystocia and birth of more heifer calves.