Effects of semen sexing kits (Heiferplus^TM and Bullplus^TM) supplemented to frozen-thawed bull semen on pregnancy rates, foetal sex ratios and selected reproductive parameters in cows

Abstract

It has been claimed that artificial insemination (AI) of cows with frozen-thawed semen treated with commercially produced kits, Heiferplus TM (HP, in favour of female gender) and Bullplus TM (BP, in favour of male gender), increases the birth chance of calves with desired sex ratio by at least 20-25% and pregnancy rates by at least 5-20%. Hence, this study was conducted to investigate the efficacy of HP and BP kits as combined with AI on the pregnancy rates, foetal sex ratios and some reproductive parameters in cows. For this, a total of 200 cows (100 Holsteins and 100 Simmentals) from three to five years old were used. Fifty Holstein and 50 Simmental cows served as controls. The other half of Holstein and Simmental cows was artificially inseminated with frozen-thawed semen treated with HP and BP, respectively. Findings showed that the AI of cows with frozen-thawed semen treated with HP had no significant effect on the pregnancy rate [52.0% (26/50) in HP group; 56.0% (28/50) in control group], female calf ratio [52.0% (13/25) in HP group; 44.4% (12/27) in control group], embryonic death, abortion, stillbirth, twinning and gestation length as compared to the control group. Similarly, AI of cows with frozen-thawed semen treated with BP did not lead to any significant effect on the pregnancy rate [64.0% (32/50) in BP group; 58.0% (29/50) in control group], male calf ratio [53.1% (17/32) in BP group; 39.3% (11/28) in control group] and other reproductive parameters as compared to the control group. In conclusion, HP and BP treatments of semen used in the AI provided only slight, non-significant increases in female (7.6%) and male (13.8%) calf ratios, respectively. Recently, sex pre-selection before fertilisation has been attempted in the field of reproductive biotechnology. The sex of foetuses is determined by whether a sperm, which performs fertilisation, carries an X or Y chromosome (Seidel 1999;Seidel and Johnson 1999). The optimal method for determining foetal sex is to separate X and Y chromosome-bearing spermatozoa before fertilisation, and to inseminate the females with the desired (sexed) semen portion. For this purpose, X and Y chromosome-bearing spermatozoa can be separated with a 85-90% success rate using flow cytometric sorting. However, the disadvantages of this method include sperm damage due to the separation procedure, increased embryonic death rate due to the usage of DNA dyes and the high financial cost of the method, which has limited its worldwide availability in field conditions (Seidel 2007).It has been claimed that insemination of cows with frozen-thawed bull semen treated with Heiferplus TM (HP) and Bullplus TM (BP) kits, marketed by a commercial company, increases the birth chance of calves with desired sex ratio by at least 20-25% and the pregnancy rate by at least 5-20%. Although the ingredients are undisclosed, the manufacturer, quoted on the internet, cites HP efficacy in both ovarian hyperstimulated and naturally ovulating cattle (Williams 2007). According to the manufac-

Reproductive performance of sexed versus conventional semen in Holstein heifers in various semiarid regions of Iran

“…The result of statistical analysis indicated that the semen type was not a significant predictor of twining rate. Similar to our findings, Healy et al (2013) and Turk et al (2015) reported that the incidence of twins insignificantly influenced by the semen sexing. Healy et al (2013) demonstrated that heavier heifers were significantly more prone to twining.…”