Prediction of first season stallion fertility of 3-year-old Dutch Warmbloods with prebreeding assessment of percentage of morphologically normal live sperm.

The research focuses on determining the predictive value of breeding soundness tests on a 3-year-old Dutch Warmblood stallion’s fertility using the percentage of morphologically normal live sperm as an indicator. It establishes that the breeding soundness test has some value in predicting breeding results in the subsequent breeding season, and that first cycle nonreturn rates can indicate a stallion’s fertility more effectively than foaling rates.

Research Context

• The researchers aimed to establish whether breeding soundness tests could reliably predict the fertility of 3-year-old Dutch Warmblood stallions in their first breeding season. These tests are part of the selection process for acquiring a breeding licence.
• The research evaluated semen parameters at the onset of the stallions’ first breeding season and related them to the nonreturn at first cycle and the foaling rate of mares bred by these stallions. The nonreturn rate here implies the percentage of mares not returning for a second insemination, indicating a successful first insemination.
• The samples consisted of two ejaculates from each of the 13 stallions studied, collected an hour apart. The total number of mares that were inseminated with chilled semen from these stallions was 1055.

Findings

• Various sperm parameters were recorded and analyzed for correlation with the first cycle nonreturn rate and foaling rate. These parameters included percentage progressive sperm motility, percentage of morphologically normal unstained spermatozoa (MNA), percentage of sperm cells with abnormal acrosomes, and the total number of spermatozoa.
• The research found a significantly positive correlation between the MNA and the first cycle nonreturn rates. This means that a higher percentage of morphologically normal sperm increases the likelihood of successful first insemination, and hence, higher fertility.
• There was no significant correlation between the foaling rates and semen characteristics or the first cycle nonreturns. So, even though the mares did not return for a second cycle, it did not necessarily result in a higher foaling rate.

Conclusion

• The results validate the relevance of breeding soundness tests in predicting the breeding performance of stallions in the breeding season following the test.
• The study also suggests that first cycle nonreturn rates can better indicate the fertilising capacity of a stallion than foaling rates.
• This research provides valuable insights that can optimize the selection process for breeding stallions, thereby improving the potency of breeding programs.