Single trait and index selection for litter size and body weight in Guinea Pigs. III. Estimation of phenotypic and genetic parameters from analysis of relatives

Data on 202 sires, 718 dams and 3192 progeny from a selection experiment were used to estimate phenotypic and genetic parameters for litter size and body weight in guinea pigs. Effects of sex and parity were estimated. Heritability estimates were obtained from offspring-parent regression and from intraclass correlation of paternal and maternal half sibs. Genetic and phenotypic correlations were estimated also. Parity effects were significant only for weight traits. Sex effects were significant of weights at several ages. Significant linear effects of number born alive were found for birth, weaning and 13-week weights. Genetic parameters estimated from similarity among relatives agreed very well with realized heritabilities and genetic correlations obtained from selection