Molecular Biomarkers of Fertility – New Tools for the Cattle Industry - 6428

Teagasc project team: Dr. Kieran Meade, Dr. Emma Finlay, Ronan Whiston Project dates: Jan 2013-Dec 2016

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Male sub-fertility is as complex as the female, and contributes to ~40% of infertility cases in humans. In the bovine, up to a 28% difference in pregnancy rates have been detected between elite sires used for AI in Ireland, despite semen from these bulls passing all the microscopy-based post-thaw semen checks. Data from our collaborators has shown that despite no differences in post thaw semen quality in terms of viability, motility or metabolism, sperm from these lower fertility bulls are less effective in penetrating cervical mucus in vitro for reasons unknown. Importantly, as AI typically bypasses the cow’s cervix, low fertility bulls continue to be used and may inadvertently exacerbate the infertility problem in both their male and female offspring. Research in humans has demonstrated that sperm from men carrying mutations in β-defensin genes are incapable of swimming through cervical mucus resulting in 40% lower fertility. This project aimed to characterize the genetic variation in β-defensin genes segregating in the bovine population and functionally assess the roles for these proteins in bull sperm function.

Questions addressed by the project: 

1. Does genetic variation across the bovine β-defensin gene family contribute to variation in fertility in AI bulls?
2. By what mechanisms do the proteins encoded by these genes influence fertility?