Bovine Sperm Sexing Alters Sperm Morphokinetics and Subsequent Early Embryonic Development

Area of Science:

• Reproductive Biology
• Animal Science
• Embryology

Background:

• Artificial insemination using sex-sorted bovine sperm often results in decreased conception rates.
• The underlying causes for reduced fertility with sexed sperm are not fully understood.

Purpose of the Study:

• To investigate the impact of sperm sexing on bovine sperm function.
• To evaluate the effects of sexed sperm on early embryonic development in vitro.

Main Methods:

• Computer-assisted semen analysis (CASA) was used to assess sperm motility (fast A, slow B, hyperactivation) before and after sexing.
• Time-lapse videomicroscopy was employed to monitor the in vitro development of embryos produced from sexed versus conventional sperm.

Main Results:

• Sexed sperm exhibited significantly reduced motility (A and B) and hyperactivation compared to conventional sperm.
• Embryos from sexed sperm showed higher rates of 4-cell stage arrest, blastomere shrinkage/fusion with lysis, and reduced blastocyst rates.
• The relative risk for cleavage was lower, and survival times were reduced for embryos derived from sexed sperm, with significant bull-dependent effects.

Conclusions:

• Reduced conception rates following sperm sexing are attributed to impaired sperm morphokinetics and compromised early embryonic development.
• Altered sperm function post-sexing decreases the likelihood of successful fertilization.
• Aberrant embryonic development, including increased arrest and lysis, further contributes to reduced fertility outcomes.