돼지의 繁殖形質에 對한 雜種强勢効果 推定

Estimate of Individual and Maternal Heterosis in Reproductive Traits of Swine

To investigate heterosis and environmental effects in the reproductive traits of swine, a total of 1,010 litters (359 purebreds, 544 two-way crossbreds and 107 three-way crossbreds) were farrowed from gilts and sows of Duroc, Landrace, Yorkshire and Hampshire. The litters were farrowed from January 1980 to December 1981. The average individual heterosis (hI) was -5.51% for pig weight at birth, -2.20% for pig weight at 21 days of age, 9.06% for litter size at birth, 7.81 for litter size at 21 days of age and -0.18% for percentage survival. The average maternal heterosis (hm) was 3.10% for pig weight at birth, 3.59% for pig weight at 21 days of age, 6.20% for litter size at birth, 9.21% for litter size at 21 days of age and 2.72% for percentage survival. The heterosis effect of purebred vs. three-way crossbred was -2.41% for pig. weight at birth, 1.39% for pig weight at 21 days of age, 15.26% for litter size at birth, 17.02% for litter size at 21 days of age and 2.54% for percentage survival. The environmental effects of the season and the parity were significant in pig weight at birth showed the high effect in the Spring and Summer. But the pig weight at 21 days of age revealed the low effect in the Summer. In the effect of parity, the pig weight at birth and at 21 days of age were very low in the first and more than the 5th parity.