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Journal of Dairy Science Vol. 37 No. 3 252-258
© 1954 by American Dairy Science Association ®
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Some Factors Affecting Age at Puberty in Holstein-Friesian Heifers1

H. W. Hawk, W. J. Tyler2 and L. E. Casida

Departments of Dairy Husbandry and Genetics, University of Wisconsin and Bureau of Dairy Industry, Madison, Wisconsin

ABSTRACT

The effects of inbreeding, calfhood scouring, and season of birth on age at first heat were studied in six sire-groups of Holstein-Friesian heifers, totaling 67 animals. No statistically significant differences were found in puberal age among the sire-groups. Inbreeding and calfhood scouring were found to delay age at puberty and also to retard calfhood growth significantly. A highly significant negative correlation was found between age at puberty and weight at 3 or 6 months of age. Adjustment of puberal ages for differences in weight at 3 or 6 months yielded evidence suggesting that inbreeding and/or calfhood scouring increased age at puberty by retarding growth. Heifers born during the spring were found to reach puberty at a significantly earlier age than those born,during other seasons of the year. No evidence was found that age at puberty is associated with the readiness with which heifers conceived.

FOOTNOTES

1 From the Department of Genetics (Paper No. 519) and Department of Dairy Husbandry; published with the approval of the director of the Agricultural Experiment Station. This study was supported in part by a grant from the Research Committee of the Graduate School from funds supplied by the Wisconsin Alumni Research Foundation and by a grant from the Emmons Blaine, Jr., Fund. Contribution from the Wisconsin Agricultural Experiment Station as a collaborator under the North Central Region Cooperative Research Project entitled "Imprgvement of Dairy Cattle Through Breeding—NC-2," conducted in cooperation with the Bureau of Dairy Industry, U.S.D.A.

2 Agent of the Bureau of Dairy Industry.






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Copyright © 1954 by the American Dairy Science Association ®.