Crossmatings were accomplished among three semi-closed lines within a population of pigs, for the purpose of investigating effects of crossbreeding on reproductive traits. Two of the lines were purebred (Berkshire and Yorkshire); the third line ("Composite") consisted of descendants from inter se matings among offspring of crosses of the Berkshire...
Eight purebred rams (four Suffolk and four Panama) previously
selected as high and low on the basis of post-weaning performance
feed test of 84 days were used each of three years. Each of the
rams was mated to approximately 25 grade Panama ewes each year.
One ram and 25 ewes...