Danish A.I. field data with sexed semen

Area of Science:

• Animal Science
• Reproductive Biology
• Dairy Cattle Breeding

Background:

• Sexed semen technology offers potential for genetic improvement in dairy herds by controlling offspring sex.
• Field data on the efficacy of sexed semen across different dairy breeds is crucial for commercial adoption.
• Previous studies have indicated variable field performance of sexed semen.

Purpose of the Study:

• To compare conception rates, non-return rates, and sex ratios of sexed versus conventional semen from the same sires.
• To evaluate breed-specific differences in the field performance of sexed semen in Danish dairy herds.
• To provide insights into the commercial viability of sexed semen technology.

Main Methods:

• Semen was collected from nine bulls (three each of Holstein, Jersey, and Danish Red Dairy Breed).
• Artificial insemination (AI) was performed by trained technicians using sexed semen and conventional semen from the same bulls.
• A total of 2087 doses were used across 63 commercial dairy herds, with a minimum of 150 sexed doses and 50 conventional doses per bull.

Main Results:

• Conception rates were lower for sexed semen compared to conventional semen: 5% lower for Danish Reds, 7% for Jerseys, and 12% for Holsteins.
• Non-return rates showed differences of 10-20% points among bulls, indicating variable field performance.
• The sex ratio of resulting calves averaged 89-93% female, consistent with the theoretical 93% female ratio.

Conclusions:

• Sexed semen demonstrated reduced conception and non-return rates compared to conventional semen in Danish dairy herds, with breed-specific variations.
• The observed sex ratios align with theoretical expectations, confirming the accuracy of semen sorting technology.
• These findings suggest that while sexed semen offers control over offspring sex, its commercial use requires careful consideration of breed-specific fertility differences.