HERITABILITY AND REPEATABILITY ESTIMATES OF MATERNAL PERFORMANCE TRAITS IN PUREBRED AND CROSSBRED DOES

Data on purebred doe (298 lillers) and combined purebred and crossbred doe (461 litters) produclion records were collected over a 2-year period (1990 and 1991) and analyzed separately to obtain heritability and repeatability estimates. Doe breed types were Californian (CAL), New Zealand White (NZW) and CAL x NZW. Litters were sired by bucks representing four breeds or lines - CAL, NZW, and control and selected synthetics. Maternal performance traits included doe body weight al parturition, gestalion length, litter size and weight al birth, 21 d, and weaning (28 d), doe production efficiency (litter weaning weighUdoe body weight), 1-21 d and 1-28 d total doe and litter feed intake, and neonatal and preweaning survival rates. A doe repeatability model was employed which consisled of fixed effects of year, season, parity, and doe breed type, and random direct additive genetic, permanent and residual effects. Sire breed and individual service sire of the litter were added to this model for the analysis of litter weaning weight. Heritability and repeatability estimates were reasonably similar for all traits studied between pooled purebred and combined purebred and crossbred data analyses. From pooled purebred doe data analysis, heritability (repeatability) eslimates for doe body weight, gestation length, and litter size al birth, 21 d, and 28 d were 0.53, 0.00, 0.13, 0.00, and 0.00 (0.72, 0.09, 0.23, 0.06, and 0.06), respectively. For doe produclion efficiency and litter weights al birth, 21 d and 28 d, heritabililies (repeatabilities) were 0.07, 0.14, 0.09, and 0.03 (0.07, 0.14, 0.09, and 0.03); however, when statislically adjusted for the corresponding litter size, heritabilities (repeatabilities) changed to 0.06, 0.00, 0.02, and 0.00 (0.06, 0.24, 0.30, and 0.28), respeclively. Heritabililies (repeatabilities) of 0.13 and 0.13 (0.30 and 0.21) were oblained for 1-21 d and 1-28 d total doe and litter feed intake. Lastly, neonatal and preweaning survival rates had herilability (repeatability) estimates of 0.13 and 0.00 (0.16 and 0.19). In summary, maternal performance traits tend to be lowly heritable (except for doe body weight) and lowly to moderately repeatable.