JDS
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Journal of Dairy Science Vol. 49 No. 7 879-886
© 1966 by American Dairy Science Association ®
This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Everett, R. W.
Right arrow Articles by Boyd, L. J.
Right arrow Search for Related Content
PubMed
Right arrow Articles by Everett, R. W.
Right arrow Articles by Boyd, L. J.

Genetic Relationship between Production and Breeding Efficiency1

R. W. Everett, D. V. Armstrong and L. J. Boyd

Dairy Department, Michigan State University, East Lansing

ABSTRACT

Breeding and production records of 10,907 Holstein and 10,537 Guernsey lactations from Adohr Milk Farms, Camarillo, California, were analyzed, to determine the phenotypic and genetic parameters of milk and fat production and five measures of breeding efficiency. The five measures of breeding efficiency were: days open, calving interval, days from parturition to first breeding, days from first breeding to conception, and services per conception.

The relationship between 120-day milk and fat production and breeding efficiency was essentially zero. Regressions of breeding efficiency on production indicated that breeding efficiency increased slightly as production increased. The regressions of breeding efficiency on age indicated that breeding efficiency increased slightly as cows got older.

The heritability of breeding efficiency was low, approximately 0.05. Heritabilities of 120-day milk and fat production were 0.18 and 0.17 for Guernseys and 0.09 and 0.06 for Holsteins, respectively. Genetic correlations between 120-day lactation production and breeding efficiency were significant and relatively large (approximately 0.50).

Due to the low heritabilities of breeding efficiency, selection for breeding efficiency or lactation production would not change breeding efficiency materially.

FOOTNOTES

1 Published with the approval of the Director of the Michigan Agricultural Experiment Station as Journal Article no. 3752.






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 1966 by the American Dairy Science Association ®.