Reproduction in Domestic and Feral Swine. I. Comparison of Ovulatory Rate and Litter Size

Abstract

Reproductive parameters were compared in one breed of domestic swine and a line of feral swine. Ovulatory rate, litter size and sex ratios of fetuses were recorded at slaughter at 80, 90, 100 or 110 days of gestation in 12 Yorkshire and 17 feral primiparous gilts. Percentages of total embryos surviving were not different for the two types of swine, averaging 70.9% and 64.7% for the obese (feral) and lean (Yorkshire) lines, respectively. Sex ratios of fetuses were 119 and 105 males/100 females for obese and lean lines and were not significantly different. The mean ovulatory rate of the feral gilts was 8.7, compared with 15.1 for the Yorkshire (P<0.001). These data indicate that the feral pig produces smaller litters than does the Yorkshire and that the smaller litter size in the feral pig is the result of a lower ovulatory rate, not higher embryonal mortality.