Genetic and Physiological Aspects of Growth, Body Composition and Feed Efficiency in Mice

Abstract

Genetic and physiological aspects of growth, body composition and feed efficiency between 3 and 8 weeks of age were studied in three lines of mice, two of which had been selected over 10 generations for high (H) and low (L) 8-week body weight; and a third, randombred control (R). The physiological parameters studied were: chemical composition of the whole body (WB) and its carcass (C) and non-carcass (NC) parts, digestible energy intake (DEI), and energy requirements for maintenance and for growth. The genetic parameters measured were: direct and correlated selection responses, direct genetic effects of the offspring (gO), maternal genetic effects (gM), direct heterosis (hO), maternal heterosis (hM) and recombination effects in the offspring (rO). ... It was concluded that the direct genetic effects account for a major part of the differences between the H, R and L lines. The proportion of maternal genetic effects was relatively small, but important for weaning traits and declined in postweaning traits. Heterosis observed in a number of traits in this study provided evidence of existence of significant non-additive genetic variance between these mouse lines. Maternal heterosis in the F₁ dams was responsible for an enhanced preweaning growth of the progeny.