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Journal of Dairy Science Vol. 30 No. 11 817-826
© 1947 by American Dairy Science Association ®
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Fertility Level in Artificial Breeding Associated with Season, Hours of Daylight, and the Age of Cattle

Ernest Mercier1 and G. W. Salisbury

Laboratory of Animal Breeding and Artificial Insemination, Department of Animal Husbandry, Cornell University, Ithaca, New York

ABSTRACT

In an investigation on the seasonal variations in fertility level of about 125,000 cows and 71 bulls of various ages bred artificially within the last 6 years in New York State, it was found that:

  1. With respect to fertility level, cattle of various ages responded differently and consistently to seasons of the year, the younger and older cattle being influenced more readily than mature cattle.
  2. Winter was the poorest breeding season of the year during this period.
  3. The fertility level of all bulls kept at this Station but artificially bred to cattle in all sections of the State from December, 1945, through November, 1946, was significantly correlated with the length of daylight, there being a lag of 1 or 2 months before the effect of daylight reached its maximum. For two groups of bulls less than 6 years of age, the correlation coefficients were not statistically significant. Thus, young bulls probably are more subject to other extraneous influences on fertility than are those from 6 to 10 years of age.

It is concluded that variations in the hours of daylight influence the fertility level of dairy cattle at this latitude, and that the response to light varies with the age of the animals involved.

FOOTNOTES

1 Now in charge of the artificial insemination program for the Department of Agriculture, Quebec, Canada






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Copyright © 1947 by the American Dairy Science Association ®.