Improvement in Production of New York Holsteins Due to Artificial Insemination

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Abstract
The first-lactation milk and fat records of 24,995 artificially sired progeny and 32,831 naturally sired progeny were compared on a within herd-year-season contemporary comparison basis over a period of nearly 10 yr. The artificially sired progeny were superior in every year of calving from 1951 through 1959, for milk and fat production. The trend in superiority was generally upward, although the low point was in 1953, followed by an increase and then a slight decline until 1959, when the superiority was greatest. Evidently, more emphasis was placed on selection of sires according to fat production of progeny than milk production. Biases in estimation of superiority of artificially sired daughters would result if over-all season averages of artificially sired and naturally sired daughters were used.
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