Abstract
Ways of increasing the reproductive efficiency of cattle through artificial insemination are reviewed. Extending the useful life, hastening puberty, adequate pre-collection stimulation, and more frequent collection are considered as they affect lifetime sperm production. The number of sperm needed to inseminate the cow is another item governing the potential number of offspring of a bull. Preservation of semen at refrigerator temperature, at ambient temperature by chemical control, by freezing and by lyophilization are discussed as means of increasing the percentage of semen available for use in artificial insemination. The research reviewed suggests that many bulls may have a potential annual calf crop of over 200,000, if genetically superior bulls can be located.