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


     

J. Anim Sci. 1988. 66:396-399.
© 1988 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 HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Quaas, R. L.
Right arrow Articles by Pollak, E. J.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Quaas, R. L.
Right arrow Articles by Pollak, E. J.

Describing Interactions in Dystocia Scores with a Threshold Model1

R. L. Quaas, Y. Zhao and E. J. Pollak

Cornell University2 Ithaca, NY 14853

Abstract

Field data on calving difficulty scores provided by the American Simmental Association were subjected to two methods of analysis: ordinary least-squares analysis and maximum likelihood with an assumed threshold model. In each analysis, the model included the interaction of sex of calf x age of dam. This interaction was readily apparent in the data (observed scale): within the youngest dams 58% of the heifer calves and 37% of the bull calves were born unassisted vs 96% and 92%, respectively, in the oldest dams. The objective was to determine if this interaction would be greatly reduced or would disappear on the underlying scale of a threshold model. The least-squares estimate of the sex difference was greatest within the youngest age-of-dam group (18 to 24 mo) and steadily declined with increasing age of dam, approaching zero for dams 6 yr and older. In contrast, the estimates of the sex difference from the threshold analysis were remarkably similar across ages of dam. It was concluded that observed interactions in calving ease data could be adequately described by a threshold model in which the effects of age of dam and sex of calf act additively on the underlying variable.

Footnotes

1 This research was supported by a grant from the Am. Simmental Assoc., Bozeman, MT.

2 Dept. of Anim. Sci., 114 Morrison Hall.




This article has been cited by other articles:


Home page
 J ANIM SCIHome page
G. L. Bennett, R. M. Thallman, W. M. Snelling, and L. A. Kuehn
Experimental selection for calving ease and postnatal growth in seven cattle populations. II. Phenotypic differences
J Anim Sci, September 1, 2008; 86(9): 2103 - 2114.
[Abstract] [Full Text] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 1988 by the American Society of Animal Science.