Sex-Sorted Semen Techniques in Bovine Reproduction

Sex-sorted semen technologies enable the predetermination of offspring sex by separating X- and Y-chromosome-bearing sperm prior to artificial insemination. The predominant commercial method employs fluorescence-activated cell sorting, which discriminates spermatozoa on the basis of DNA content. This approach has advanced genetic management in dairy and beef herds by optimising the ratio of female to male calves, thereby improving economic efficiency and reducing environmental impact. Despite the benefits, sex sorting can impair sperm motility and viability and lower conception and calving rates. Recent efforts focus on mitigating these drawbacks through refinements in sperm handling, optimisation of sorting parameters and exploration of alternative separation strategies. These include immunological and receptor-activation approaches that leverage surface markers or functional differences between X and Y sperm. Globally, improvements in throughput, dosage and post-sorting culture conditions are expanding the practical applications of sexed semen in commercial breeding programmes.

Research from Nature Portfolio

Research investigating the impact of commercial sex sorting on bovine sperm function revealed that sorted semen exhibits reduced progressive motility, hyperactivation and early embryonic viability. Altered sperm morphokinetics were linked to increased arrest during cleavage and diminished blastocyst formation, providing mechanistic insights into lower pregnancy rates observed in the field. A subsequent meta-analysis of over 70 trials demonstrated overall reductions in non-return, pregnancy and calving rates when using sex-sorted versus conventional semen. The analysis also highlighted the benefits of higher sperm numbers per straw, fresh sorting and technological refinements introduced after 2015, which collectively mitigated fertility losses and narrowed the performance gap with unsexed doses.

Sex-Sorted Semen Techniques in Bovine Reproduction publication trend

The graph below shows the total number of articles in sex-sorted semen techniques in bovine reproduction across all publications each year (not limited to Nature Index journals).

Technical terms

Sex-sorted semen: Semen in which spermatozoa have been separated by sex chromosome content to enrich for X- or Y-bearing cells.

Fluorescence-activated cell sorting (FACS): A flow cytometry–based method that labels and sorts cells according to fluorescent markers, here DNA-binding dyes.

Computer-assisted semen analysis (CASA): Automated imaging technology used to quantify sperm motility and kinematic parameters.

Hyperactivation: A vigorous sperm motility pattern characterised by high-amplitude flagellar beats necessary for oocyte penetration.

Proteomics: The large-scale study of the protein composition of cells or biological samples to identify differentially expressed molecules.

Toll-like receptor 7/8 (TLR7/8): Pattern-recognition receptors encoded on the X chromosome that, upon activation, can modulate X-sperm motility.

References

1. Sex Manipulation Technologies Progress in Livestock: A Review. Frontiers in Veterinary Science (2020).
2. Bovine Sperm Sexing Alters Sperm Morphokinetics and Subsequent Early Embryonic Development. Scientific Reports (2020).
3. The reproductive success of bovine sperm after sex-sorting: a meta-analysis. Scientific Reports (2021).
4. Differential protein profile in sexed bovine semen: shotgun proteomics investigation. Molecular Omics (2014).
5. Bovine semen sexing: Sperm membrane proteomics as candidates for immunological selection of X‐ and Y‐chromosome‐bearing sperm. Veterinary Medicine and Science (2021).
6. Activation of Toll-like receptor 7/8 encoded by the X chromosome alters sperm motility and provides a novel simple technology for sexing sperm. PLOS Biology (2019).