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Thesis (M.S.)—University of Nebraska—Lincoln, 1955. Department of Animal Husbandry.


Copyright 1955, the author. Used by permission.


The purpose of this study was to determine the efficiency and effectiveness of selection in swine for number of pigs farrowed per litter, number of pigs weaned per litter, litter weight at weaning, average pig weight in litters at weaning, individual pig weight at 56 and 154 days of age, and selection index at 154 days for four systems of mating. The four systems of mating were crosses between breeds, crosses between inbred lines of Durocs, and outbreeding and inbreeding within the Duroc breed.

Mating types were analysed for differences in the sow productivity and individual performance items included in this study. Differences in selection intensity between the outbreds and the other groups were studied. Individuals in the outbred group were not chosen for the breeding herd by the means of the selection index used for the other three groups.

The data for this study were collected at the North Platte Experiment Station as part of the Nebraska Project of the Regional Swine Breeding Laboratory. Data included 168 litters from 3 fall farrowing seasons. The seasons specifically included were the fall seasons of 1952, 1953 and 1954.

Advisor: Cecil T. Blunn