Biology of bovine sperm and breeding soundness (Proceedings)
Aug 01, 2008
CVC IN KANSAS CITY PROCEEDINGS
Approximately 20 years ago, studies centered on the ability of bull sperm to fertilize eggs in vitro. Higher fertility semen donors produced sperm that were more readily 'capacitated' in lab media. Therefore, the hunt was on to identify differences in seminal components from high and low fertility bulls that altered the ability of sperm to capacitate. A protein produced in the seminal vesicles, prostate, and Cowper's glands named fertility-associated antigen (FAA) binds to sperm during ejaculation. An antibody-based test was developed which utilizes a lateral-flow cassette and can be conducted in 20 minutes as part of a breeding soundness qualification. Bulls with detectable FAA are 16-19% more fertile than herdmates lacking measurable FAA, even though physical characteristics are identical between those two groups of bulls. Field trials indicate that 25% of bulls will be identified as FAA-negative and should be removed as prospective breeders.
Why Predict Fertility?
Breeding Soundness Evaluation (BSE)
With "mad cow" disease caused by bovine spongiform encephalopathy (BSE), the time has come to find another term to describe breeding soundness in bulls. Therefore, for purposes of this discussion, a former BSE will now be called a breeding soundness qualification (BSQ).
What does a BSQ do? The American Society for Theriogenology has developed guidelines that are meant to be used to identify a bull as a "potential satisfactory breeder" (Chenoweth et al., 1992; Hopkins and Spitzer, 1997). Besides a general physical examination, a BSQ also includes measuring scrotal circumference and evaluating a semen sample. Minimum thresholds have been established for breed-type and age that establish whether or not a bull passes a BSQ. In general, for non-Brahman cattle, at 14 months of age, the following criteria should be satisfied: