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

This Article Full Text 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 Google Scholar Google Scholar Articles by Guerra, J. L. L. Articles by Blouin, D. C. Search for Related Content PubMed PubMed Citation Articles by Guerra, J. L. L. Articles by Blouin, D. C.

Genetic parameters for calving rate and calf survival from linear, threshold, and logistic models in a multibreed beef cattle population¹

J. L. L. Guerra^*,2, D. E. Franke^*,3 and D. C. Blouin

^* Departments of Animal Sciences, and and Experimental Statistics, Louisiana State University Agricultural Center, Baton Rouge 70803

³ Corresponding author: dfranke{at}agctr.lsu.edu

Generalized mixed linear, threshold, and logistic sire models and Markov chain, Monte Carlo simulation procedures were used to estimate genetic parameters for calving rate and calf survival in a multibreed beef cattle population. Data were obtained from a 5-generation rotational crossbreeding study involving Angus, Brahman, Charolais, and Hereford (1969 to 1995). Gelbvieh and Simmental bulls sired terminal-cross calves from a sample of generation 5 cows. A total of 1,458 cows sired by 158 bulls had a mean calving rate of 78% based on 4,808 calving records. Ninety-one percent of 5,015 calves sired by 260 bulls survived to weaning. Mean heritability estimates and standard deviations for daughter calving rate from posterior distributions were 0.063 ± 0.024, 0.150 ± 0.049, and 0.130 ± 0.047 for linear, threshold, and logistic models, respectively. For calf survival, mean heritability estimates and standard deviations from posterior distributions were 0.049 ± 0.022, 0.160 ± 0.058, and 0.190 ± 0.078 from linear, threshold, and logistic models, respectively. When transformed to an underlying normal scale, linear sire, mixed model, heritability estimates were similar to threshold and logistic sire mixed model estimates. Posterior density distributions of estimated heritabilities from all models were normal. Spearman rank correlations between sire EPD across statistical models were greater than 0.97 for daughter calving rate and for calf survival. Sire EPD had similar ranges across statistical models for daughter calving rate and for calf survival.

Key Words: beef cattle • genetic parameter • reproductive trait • statistical method