Heritabilities and Genetic and Phenotypic Correlations for Prebreeding Traits, Reproductive Traits and Principal Components

Abstract
Twenty-five variables measured before breeding and six measures of reproduction on 2,095 gilts from the University of Nebraska Gene Pool population were analyzed to estimate heritabilities and phenotypic and genetic correlations. Principal components were derived separately from the prebreeding and reproductive phenotypic correlation matrices and were analyzed as new traits. The heritabilities of most traits were in general agreement with the average of the literature estimates with the exception that the heritability of litter size at birth was .72 compared to a literature average of .10. Phenotypic correlations among growth traits were large and positive. Phenotypic correlations of ovulation rate with litter sizes and weights were positive but small and nonsignificant. Phenotypic correlations among litter sizes and litter weights at birth and 42 days were large and positive. Several of the measures of growth had significant positive phenotypic correlations with ovulation rate but not with litter sizes or litter weights. All genetic correlations had large standard errors and none were statistically significant. Genetic correlations among growth traits were large and positive. Genetic correlations of ovulation rate with litter sizes and weights were negative and, with the exception of number born, were large. Genetic correlations among litter size and litter weight at birth and 42 days were large and positive. Seven principal components derived from the prebreeding traits accounted for 79.8% of the total variation of the 25 variables. Three principal components derived from the reproductive traits accounted for 94.6% of the total variation of the six variables. Principal components were very useful in evaluating interrelationships among traits within a group but were not very useful in elucidating the relationship between groups. Copyright © 1978. American Society of Animal Science . Copyright 1978 by American Society of Animal Science

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