Use of Sexed Semen in Breeding

Bovine semen contains roughly 50% each of male (Y) and female (X) sperm. The fertilization of bovine egg by X sperms results in the birth of female calves, whereas Y sperms result in male calves. Sex sorting technology involves separating male and female cells.

The accuracy of this technique is almost always 85-95% of the sex chosen.

The potential benefits of incorporating sexed semen into the breeding program include:

  • Select potential dams and produce more replacement heifers from genetically superior animals.
  • Minimize the number of unwanted male dairy calves.
  • Accelerate herd expansionarrowMinimize biosecurity risks associated with bringing in animals from different herds.
  • Improve animal welfarearrowEasily calved heifers can be selected.
  • Increase herd genetic gain compared with use of non-sexed semen.

In dairy herds, a good strategy could be to use sexed semen to generate replacements only and beef semen on all dams that are not suitable for generating replacements. This way, genetic gain occurs in the dairy herd, and the value of beef output from the dairy herd are increased. Greenhouse gas emissions from beef are also reduced1.

The most reliable method of sperm sexing is using a high-speed flow cytometer. This procedure is safe for the sperm’s genetic material, and there is no increase in the abortion rate or differences in gestation length, neonatal death, calving difficulty, birth weight, weaning weight, or live births when sexed sperm is compared to unsexed control sperm.

However, the conception rates of artificial insemination with conventional semen have been shown to be significantly higher compared to sexed semen for heifers and cows, probably because the physical and chemical stress that can damage the sperm during the sorting process2.

use of sexed semen

Sexed sperm decreases pregnancy rates.

With excellent management, pregnancy rates with sexed sperm are 70-90% of controls.

E.g.: If the control pregnancy is 70%, the sexed rate is 49-63% pregnant.

With average management, pregnancy rates with sexed semen are 50-70% of controls.



Drawbacks:

Lower pregnancy rate and higher costs of sexed semen preclude widespread application at the commercial level in dairy cattle. Sexed semen is more expensive than conventional semen. The average premium may be approximately $30 per straw compared to conventional semen3. This varies with sire.

To achieve good success rates with sexed semen it is necessary to have:

  • Well managed animals, including good nutrition
  • Careful handling of semen
  • Excellent estrus detection or synchronization protocols
  • Well-trained inseminators

References

  1. Holden SA, Butler ST. Review: Applications and benefits of sexed semen in dairy and beef herds. Animal 2018;12(s1):s97-s103.
  2. Mocé E, Graham JK, Schenk JL. 2006. Effect of sex-sorting on the ability of fresh and cryopreserved bull sperm to undergo an acrosome reaction. Theriogenology, v. 66, n.1, p. 929-936
  3. https://articles.extension.org/pages/25983/the-economics-of-sexed-semen-in-dairy-heifers-and-cows4Garner DL, Seidel GE. History of commercializing sexed semen for cattle. Theriogenology 2008; 15;69(7):886-95