SOW PRODUCTIVITY COMPARISONS FOR FOUR BREEDS OF SWINE: PUREBRED AND CROSSBRED LITTERS

Data were collected from 366 litters produced in a four-breed (Duroc, Yorkshire, Spotted and Landrace) diallel mating system. Purebred and crossbred litters were farrowed during five consecutive (fall and spring) farrowing seasons (fall 1976 through fall 1978). Litters were produced by randomly mating boars of each breed to at least one female of each breed. Litter size and weight at birth, litter size and weight at 42 d and pig survival to 42 d were analyzed. There were significant parity effects for all traits except survival rate, and significant year and season effects for litter size at birth and 42 d and litter weight at 42 d. Large breed of dam differences were detected for most sow productivity traits. Litters from Spotted females were smaller and lighter in weight. Landrace females were most productive in terms of litter weight at weaning and proportion of their pigs raised from birth to weaning. Breed of sire differences were not significant for any trait. Significant heterosis estimates were obtained for litter size and weight at weaning and for survival rate. Crossbred litters had .79 more pigs, were 11.72 kg heavier at weaning and had a 5.56% greater survival rate than the average of all purebreds