Genetic selection for small body size in Yucatan miniature pigs

Yucatan miniature swine exhibiting smaller than average size and weight were selected as foundation stock for a miniaturization program. The F1 progeny from four matings of parent stock were evaluated based on weight through 24 months of age. Those animals with a mature weight at least 20% below the average of the population were selected as breeding stock for the succeeding generations. The selected F1 boars, when compared in size to the mean weight of unselected adult boars, were significantly lighter (p less than 0.01). Selected F1 sows were significantly lighter (p less than 0.001) compared to unselected sows of a comparable age.