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The knobbed acrosome defect in beef bulls.
Summary
A knobbed acrosome defect in beef bulls, particularly Charolais, causes infertility. This sperm abnormality, characterized by head defects, may have a genetic basis, impacting breeding success.
Area of Science:
- Veterinary Science
- Animal Reproduction
- Genetics
Background:
- The knobbed acrosome defect is a morphological abnormality of spermatozoa.
- This defect has been previously observed in certain cattle breeds.
Purpose of the Study:
- To investigate the incidence and characteristics of the knobbed acrosome defect in beef bulls.
- To determine the potential genetic basis and impact on fertility of this sperm defect.
Main Methods:
- Semen analysis of 2054 beef bulls using eosin-nigrosin staining.
- Electron microscopy for detailed ultrastructural examination of spermatozoa.
- Pedigree analysis of affected Charolais bulls.
- Breeding trials with affected bulls.
Main Results:
- The knobbed acrosome defect was identified in 16 out of 2054 bulls (0.78%).
- Affected bulls exhibited 25-100% spermatozoa with the defect, primarily a flattened or indented sperm head apex.
- Charolais bulls showed a higher incidence, suggesting a potential genetic predisposition.
- Electron microscopy confirmed the defect's similarity to that in Friesian bulls.
- Breeding trials confirmed infertility in bulls with a high incidence of knobbed acrosomes.
Conclusions:
- The knobbed acrosome defect is a significant cause of infertility in beef bulls.
- A genetic component is likely involved, particularly in the Charolais breed.
- Further research into genetic markers and breeding strategies is warranted.
