Influence of Sexcel (Gender Ablation Technology) Gender-Skewed Semen in Fixed-Time Artificial Insemination of Beef Cows and Heifers.

Previous research has indicated that gender-sorted semen has decreased conception rates compared to conventional semen. A new method to skew the gender ratio of semen has been developed that does not use traditional sorting technology. Thus the objective of this study was to evaluate the use of this gender-skewed semen in a fixed-time AI protocol. Beef heifers and cows (n = 878) in 6 herds were synchronized with the 7-d CO-Synch plus CIDR protocol, and inseminated (AI) at the appropriate time after CIDR removal (cows 60 to 66 hrs; heifers 52 to 56 hrs). Estrus detection aids were applied at CIDR removal and estrus activity was determined at time of AI. Animals remained separated from bulls for at least 10 d after AI. Pregnancy success and fetal age were determined between d 28 and 70 after AI. Semen from 5 sires was utilized in this study, with two sires used in each herd. Sire 1 used in all herds and the second sire varied by herd (both conventional and gender-skewed semen of each sire was used in each herd). Data were analyzed using the GLIMMIX procedure in SAS and included the influence of semen type, estrus expression, semen type by estrus expression, dam age, and sire in the model. Herd was included as a random variable. Overall, conventional semen had greater conception rates compared to gender-skewed semen (P < 0.01; 67% vs 52%), and cows that had fully activated patches and partially activated patches had greater conception rates compared to animals that had not exhibited estrus (P < 0.01; 69%, 65%, and 45%). There was no semen type by estrus expression interaction (P = 0.24). Among animals that had activated patches (P = 0.06; 73% vs 65%) and animals with partially activated patches (P = 0.06; 72% vs 59%) conception rates tended to be greater for conventional semen. Among animals that did not exhibit estrus conception rates were greater for conventional semen (P < 0.01; 56% vs 33%). There was no effect of dam age (P = 0.40) or sire (P = 0.92) on conception rates. In conclusion, Sexcel^TM gender-skewed semen can successfully be used in fixed-time AI protocols among animals that exhibit estrus, but caution should be used among animals that do not exhibit estrus.