ABSTRACT
ESTIMATION OF GENETIC PARAMETERS AND GENETIC TRENDS FOR PRODUCTION TRAITS IN BROILER BREEDER POPULATIONS USING THE MULTIPLE-TRAIT BLUP ANIMAL MODEL
Mehran Meschian
Advisor:Professor I. McMillan
University of Guelph, 2007
Production traits of the sire (Cornish) and dam (White Rock) populations of meat-type chicken were measured during ten generations of multiple-trait selection. Data from growth rates, feed consumption, carcass and reproduction traits were examined to estimate heritabilities, genetic correlations among the traits and genetic responses to selection in a multiple-trait BLUP animal model and REML estimation. Heritability and the selection pressure for each selected trait along with the genetic correlations were the most important factors determining the rate of genetic responses. Due to the moderate to high heritability estimates for growth traits, carcass traits and adjusted feed consumption for body weight, and favorable relationships among these traits, genetic responses in the multiple-trait selection programs were satisfactory. Low heritability of egg production and the negative correlation with body weight, made improvement of this trait difficult, so selection based on multiple-trait BLUP prediction together with management revise may result in better response.