Reproduction of 3/4 White Composite and 1/4 Duroc, 1/4 Meishan, 1/4 Fengjing, or 1/4 Minzhu gilts and sows
1998
Females were either 1/4 Duroc, 1/4 Meishan, 1/4 Fengjing, or 1/4 Minzhu, and the remainder were 3/4 White Composite. A greater percentage of Fengjing crosses reached puberty than Duroc or Minzhu (P < .05), and Meishan crosses were intermediate and not different (P > .05) from other breed types. After adjusting for differences in percentage detected owing to termination of observation for estrus, breed types ranked Fengjing, Meishan, Minzhu, and Duroc from youngest to oldest at puberty with approximately 14 d between adjacent breed types. Meishan and Fengjing crosses had a greater (P < .05) ovulation rate than Minzhu or Duroc crosses. With the exception of number of fetuses at 100 d and average fetal weight at 60 d, differences among breed types were not detected (P > .05) for litter or uterine traits measured on gilts slaughtered at 60 or 100 d of gestation. Total number of pigs born was greater (P < .05) for 1/4 Fengjing than for 1/4 Duroc gilts. Gestation length, number born alive, number weaned, litter birth weight, or litter weaning weight for gilts did not differ (P > .05) among breed types. Duroc crosses were heavier (P < .01) than Chinese crosses at d 1 and 28 after farrowing, but breed types did not differ (P > .05) for backfat thickness at those times. Breed types did not differ (P > .05) for the ratio of litter gain from 0 to 28 d/total Mcal or any of the component traits in the ratio. Postweaning estrus activity, conception rate, and litter and uterine traits of sows bred for second parity were not affected (P > .05) by breed type. These analyses indicate that crossbred gilts containing 1/4 Meishan, 1/4 Fengjing, or 1/4 Minzhu will reach puberty earlier, have larger litters, and weigh less at first parity than gilts containing 1/4 Duroc, but they do not have any significant advantage in litter size at second parity.
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