Abstract
A complete diallel using three inbred strains of mice (C3H/He, C57BL/6J and SWR/J) was made to examine preweaning growth of young, the weight of mammary glands of mothers and the relationship between them. Litter sizes were standardized to either six or eight at birth.The differences between strain-of-dam, strain-of-sire and litter size groups in average body weight of full sibs at 12 days were not significant. The difference between litter size groups in weight of dried-defatted mammary gland of mothers 12 days after delivery (DDMW) was significant. When average birth weight was fixed, the partial correlation between DDMW and 12-day weight, calculated within litter size and mating class, was +0.54. Heterosis in average birth weight and 12-day weight was observed. Relationships between preweaning growth criteria are discussed.