HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Naazie, A. Articles by Berg, R. T. Search for Related Content PubMed PubMed Citation Articles by Naazie, A. Articles by Berg, R. T.

Factors Influencing Calving Difficulty in Beef Heifers¹

University of Alberta² Edmonton, ALberta, T6G 2P5, Canada

Abstract

Records of 547, 2-yr-old heifers of three breed groups were used to evaluate the relative influence of dam's body and pelvic measurements, calf birth weight, sire birth weight and some relative measures (ratios) of calf birth weight and dam weight at calving on calving difficulty. The data were analyzed by regression and least squares procedures. The full model explained 32.5% of the variation in calving difficulty score. The linear effect of calf birth weight was the most important variable, accounting for 17.8% reduction in the coefficient of determination, and together with dam weight at calving and the quadratic effect of calf birth weight it accounted for 92% for all the variation explained by the full model. Dam weight at calving was negatively related to calving difficulty. Breed, year and sex of calf did not influence calving difficulty score, except when the calf birth weight or dam weight or both were excluded from the model. When calf birth weight was expressed as a ratio of the dam's weight at calving, hip height and pelvic measurements, the total model explained 34.8% of the variation in calving difficulty score. The ratio of calf birth weight to dam weight was the most important variable (R² = 26.8%). Ratios of calf to dam weight at calving and calf weight to the vertical pelvic diameter (R² = 29.3%) were the only significant factors when the effects of calf birth weight and dam weight were removed from the model. Pelvic measurements, on their own, did not influence calving difficulty score in this study (P > .1), but small pelvic dimensions tended to be associated with higher calving difficulty scores.

¹ Computing and statistical assistance provided by R. Weingardt of the Anim. Sci. Dept. is gratefully acknowledged.

² Dept. of Anim. Sci.

This article has been cited by other articles:

				J. A. Arango, L. V. Cundiff, and L. D. Van Vleck Genetic parameters for weight, weight adjusted for body condition score, height, and body condition score in beef cows J Anim Sci, December 1, 2002; 80(12): 3112 - 3122. [Abstract] [Full Text] [PDF]