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


     

Journal of Dairy Science Vol. 72 No. 3 671-677
© 1989 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 Similar articles in PubMed
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 Buttazzoni, L.
Right arrow Articles by Mao, I. L.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Buttazzoni, L.
Right arrow Articles by Mao, I. L.

Genetic Parameters of Estimated Net Energy Efficiencies for Milk Production, Maintenance, and Body Weight Change in Dairy Cows1

Luca Buttazzoni2 and I. L. Mao

Department of Animal Science, Michigan State University, East Lansing 48824-1225

ABSTRACT

Net efficiencies of converting intake energy into energy for maintenance, milk production, and body weight change in a lactation were estimated for each of 79 Holstein cows by a two-stage multiple regression model. Cows were from 16 paternal half-sib families, which each had members in at least two of the six herds. Each cow was recorded for milk yield, net energy intake, and the three efficiency traits. These traits were analyzed in a multitrait model containing the same 14 fixed subclasses of herd by season by parity and a random factor of sires for each of the five traits. Restricted maximum likelihood estimates of sire and residual (co)variance components were obtained by an expectation maximization algorithm with canonical transformations. Between milk yield and net energy intake, net energy efficiencies for milk yield, maintenance, and body weight change, the estimated phenotypic correlations were .36, –.02, .08, and –.06, while the genetic correlations were .92, .56, .02, and –.32, respectively. Both genetic and phenotypic correlations were zero between net energy efficiency of maintenance and that of milk yield and .17 between net energy efficiency of body weight change and that of milk yield. The estimated genetic correlation between net efficiency for lactation and milk yield is approximately 60% of that between gross efficiency and milk yield. With a heritability of .32~.49, net energy efficiency for milk yield may be worth consideration for genetic selection in certain dairy cattle populations.

FOOTNOTES

1 Michigan Agricultural Experiment Station Journal Article Number 12582.

2 Present address: Italian Livestock Association (AIA), via G. Tomassetti 9, 00161 Roma, Italy.






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 1989 by the American Dairy Science Association ®.