RIB AND VERTEBRAL NUMBERS IN SWINE: II. GENETIC ASPECTS

Abstract

Genetic parameters for rib and vertebral number in swine were estimated from data for 4,219 pigs produced by 78 sires and 359 dams of the Lacombe breed. Regressions of offspring on mid-parent were.599 ±.017 for vertebral number and.734 ±.020 for rib number and the corresponding full sib correlations estimated from the analysis of variance were.591 ±.071 and.591 ±.060. The genetic correlation between these two skeletal traits was estimated as.813 ±.022 by the regression of offspring on mid-parent and.792 ±.016 by the analysis of components of covariance.Continuous genetic variation for both traits was demonstrated. The modal phenotype (i.e., 16 pairs of ribs and 22 vertebrae) produced progeny more uniform for both traits than did parents of non-modal phenotypes. Bilateral asymmetry (within-pig variance) was also least among progeny of "modal" parents.