Field evaluation of sexed and conventional semen in Holstein-Friesian cows: Linking semen quality with fertility and calf sex ratio across climatic zones.

BACKGROUND AND AIM: Sexed semen is increasingly used in dairy breeding programs to enhance herd productivity by increasing the proportion of female calves. However, concerns remain regarding possible trade-offs between semen processing, post-thaw quality, fertility outcomes, and calf sex ratio under field conditions, particularly in smallholder production systems and varying climates. This study evaluated laboratory semen quality and field reproductive performance of sexed and conventional semen in Holstein-Friesian cows across different climatic zones.

MATERIALS AND

METHODS

The study combined laboratory semen evaluation and a multisite field trial. Semen was processed using Percoll density gradient centrifugation (PGDC) for sexing and subsequently cryopreserved. Post-thaw quality parameters, including motility, viability, abnormalities, concentration, plasma membrane integrity, intact acrosome cap, total motile spermatozoa, and DNA fragmentation, were assessed and compared with conventional semen using an independent t-test. Field performance was evaluated in 300 clinically healthy cows from three smallholder dairy locations representing low, moderate, and high temperature-humidity index zones. Cows were randomly assigned to receive single- or double dose artificial insemination with either semen type. Non-return rate, conception rate, calving rate, and calf sex ratio were analyzed using Fisher's exact and chi-square tests, with significance set at p < 0.05.

RESULTS

Sexed semen showed motility comparable to conventional semen, while viability, concentration, plasma membrane integrity, and intact acrosome cap differed significantly between treatments (p < 0.05). Abnormalities, total motile spermatozoa, and DNA fragmentation were not significantly different (p > 0.05). Across locations, non-return rate, conception rate, and calving rate did not differ significantly between semen types or dosing strategies (p > 0.05). Nevertheless, reproductive performance tended to be higher in the cooler climatic zones. Sexed semen produced a higher proportion of female calves than conventional semen, indicating successful enrichment of X-bearing spermatozoa under field conditions.

CONCLUSION

Sexed semen produced through PGDC maintains acceptable post-thaw quality and field fertility comparable to conventional semen while improving the likelihood of female calf production. Climatic conditions, particularly lower temperature-humidity index, appear to support better reproductive outcomes. These findings support the practical use of sexed semen in smallholder dairy systems, although long-term multilocation studies integrating environmental and management factors are recommended to optimize reproductive efficiency and sustainability.