Chromosome abnormalities.

Chromosome abnormalities have been described in food animals since 1964. Some are self-limiting because they cause sterility or other developmental defects incompatible with normal growth and development, making them unacceptable for production systems. Others, however, cause no discernible phenotypic abnormalities but, in breeding animals, result in increased levels of embryonic mortality and reduced litter size. Although the extent of loss of reproductive efficiency is not entirely understood at this time, care must be exercised in recommending animals carrying a chromosome abnormality to be used as breeding stock. This is of particular concern if animals are to be used extensively in artificial insemination programs.