Maternal and sex-linked genetic effects in broiler parent stocks.

Sire and dam populations of chickens were synthesized from commercial broiler parent stocks at the Animal Research Centre, Ottawa. The production of two-way and four-way crosses during synthesis permitted measurement of maternal and sex-linked genetic effects on body weight and conformation traits. Sex-influenced effects were also measured. Reciprocal cross differences were minimal. Consequently, there was no evidence among stocks within parental type of maternal effect differences and only minimal evidence of sex-linked genetic effects. As expected, sex-influenced effects were large. Hence, it appears that breeders must work within strains or stocks to improve maternal and sex-linked genetic effects for body weight and conformation.