J. Anim Sci.
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

J. Anim Sci. 1950. 9:593-601.
© 1950 American Society of Animal Science
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 Jafar, S. M.
Right arrow Articles by Casida, L. E.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Jafar, S. M.
Right arrow Articles by Casida, L. E.

Causes of Variation in Length of Gestation in Dairy Cattle1

S. M. Jafar, A. B. Chapman and L. E. Casida2

University of Wisconsin

Abstract

The average length of 384 gestation periods was 278.2 days with a standard deviation of 4.8 days. Male calves were carried a significantly longer period of time than females. The order of calving had a significant effect in the female calves but not in the males. There was a positive correlation between the length of gestation period and the heart girth measurement. No effect of year and season of calving on the length of gestation was indicated. There was a highly significant positive correlation between the length of gestation and the birth weight of the calf. Neither the inbreeding of the dam nor the inbreeding of the calf had a significant effect.

The genotype of the calf was responsible for 48 percent of the total variance in sex adjusted records, of which 32 percent was due to the additive gene effects and 16 percent due to dominance deviations. The dam was responsible for 21 percent of the variance (six percent due to the additive gene effects and 15 percent due to permanent environmental causes and dominance deviations effective directly through the dam). Characteristics of the calf seemed about three times as important as the characteristics of the dam.

Footnotes

1 Paper No. 431 from the Department of Genetics. Published with the approval of the Director of the Agricultural Experiment Station.

2 The authors are grateful to Dr. W. Wisnicky and Mr. Tom Webster for their assistance in the collection of data. They also wish to acknowledge the help of Dr. J. F. Crow in the statistical analysis.






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 1950 by the American Society of Animal Science.