Application of gender-ablated semen during timed artificial insemination following oestrous synchronization in dairy and beef cows.

The objectives of this study were to compare oestrus synchronization expression and conception rate following TAI with frozen-thawed X-sexed or unsexed semen in dairy and beef cows. For this study 227 cows (dairy; n = 130 and beef; n = 97) were assigned to a 9-day Ovsynch + controlled intravaginal drug release (CIDR) protocol. All cows were timed artificially inseminated (TAI) using X-sexed or unsexed semen from eight sires. Each semen type was obtained from four sires [two dairy (Holstein Friesian) and two beef (Angus)]. Pregnancy detection was performed on Days 35, 65 and 95 following TAI by transrectal ultrasonography and hand palpation. The proportion of oestrus response was higher in dairy (85.3%) cows compared with beef (65.0%) cows (p < 0.05). Overall, dairy (X-sexed; 61.9% and unsexed; 62.0%) cows had greater conception rates on Day 35 compared to beef (X-sexed; 56.0% and unsexed; 52.2%) cows (p < 0.05). Concurrently, on Day 95, overall conception rates in dairy (X-sexed; 41.4% and unsexed; 48.5%) cows were greater than beef (X-sexed; 38.0% and unsexed; 37.0%) cows (p < 0.05). Pregnancy/embryo losses between Days 35 and 65 in dairy (X-sexed; 33.3% and unsexed; 18.2%) cows and beef (X-sexed; 28.6% and unsexed; 29.2%) cows were recorded (p < 0.05). Dairy (X-sexed; 7.7% and unsexed; 8.3%) cows had higher incidence of pregnancy-cy losses between Days 66 and 95 when compared to beef (X-sexed; 5.0% and unsexed; 0.0%) cows (p < 0.05). Oestrus response and conception rates in dairy and beef cows were satisfactory. Advanced reproductive biotechnologies can successfully utilize gender-ablated semen in organized emerging cattle farming systems.