Reproduction of F1 Meishan, Fengjing, Minzhu, and Duroc gilts and sows

Gilts were the progeny of eight Duroc, nine Meishan, eight Fengjing, and seven Minzhu boars mated to composite (1/4 Chester White, 1/4 Landrace, 1/4 Large White, and 1/4 Yorkshire) females. Age at puberty was youngest (P < .05) for Meishan and Fengjing crosses followed by Minzhu crosses and then Duroc crosses. Fengjing crosses had a higher (P < .05) ovulation rate than Meishan or Minzhu crosses, which had a higher (P < .05) ovulation rate than Duroc crosses. Meishan and Fengjing crosses had larger (P < .05) litters than Duroc crosses at 60 and 100 d of gestation, at birth, and at weaning. Minzhu crosses also had larger (P < .05) litters than Duroc crosses at all stages but were significantly lower than Meishan and Fenjing crosses only for litter size at 100 d of gestation. Duroc crosses were heavier (P < .05) at farrowing than all three Chinese crosses. Breed groups differed (P < .05) for backfat thickness at weaning but not at farrowing. Duroc crosses were the least efficient (P < .05) in converting feed energy into litter gain from birth to weaning; Fengjing crosses were less efficient (P < .05) than Minzhu crosses but neither differed significantly from the intermedite value of the Meishan crosses. Chinese crosses returned to estrus sooner after weaning (P < .05 than Duroc crosses. Ovulation rate at second parity was highest for Fengjing crosses followed by Meishan, Duroc, and Minzhu crosses; difference among nonadjacent means were significant (P < .05). Differences among crosses were not large or significant for number of fetuses at 100 d of gestation at second parity. Results indicate Meishan and Fengjing can be used to produce crossbred gilts that have a higher level of reproductive performance than Duroc crossbred gilts; the reproductive performance of M zhu crosses would be intermediate. However, 1 Chinese crosses would not be expected to have an advantage in litter size at second parity.