Date of this Version
Within-herd contemporary comparisons of the first-lactation production of registered and nonregistered cows in herds enrolled in the New York Dairy Herd Improvement Associations suggest only small genetic differences between registered and nonregistered cows. In general, the registered Holsteins exceeded in production their nonregistered herd-mates, whereas the nonregistered cows had a slight advantage over their registered herd-mates for the Ayrshire, Guernsey, and Jersey breeds.
Artificially sired cows had consistently higher production than their naturally sired herd-mates for all breeds. A definite increase in this advantage was noted for Holsteins in more recent years. No trend was apparent in the comparison of artificially sired registered and nonregistered cows for any of the breeds.