SERUM CHOLESTEROL, ACTIVITY, FEED INTAKE, AND BODY WEIGHT IN LINES OF MICE SELECTED FOR GROWTH

Abstract

Feed intake, growth and serum cholesterol (SC) were recorded on 102 male mice, and voluntary physical activity and SC were recorded on 113 male mice from lines selected for maximum 21- to 42-day weight gain (H), for minimum 21- to 42-day weight gain (L), and from a random-bred unselected control line (C). Voluntary physical activity in a revolving wheel was recorded for a 22-h period every sixth day from 3 to 10 weeks of age. Growth and feed intake on two different diets (diet 1 containing 4.5% fat and 23.4% protein; diet 2 containing 11% fat and 17% protein) were measured three times per week and rate of weight gain was calculated on a weekly basis. Blood samples were obtained by sinus orbital bleeding at 5 and 10 weeks of age after six hours fasting and analyzed for SC by gas chromatography. A least squares analysis of variance of the SC data using a model including lines, diets, ages and all possible interactions indicated highly significant differences in the main effects and in most of the interactions. SC and growth were higher and feed intake was lower in mice on diet 2. SC values (mg/100 ml) were 143.3, 124.1 and 132.2 at 10 weeks of age for H, C and L line animals fed diet 1 and 220.3, 178.1 and 180.4 for animals fed diet 2. An analysis of variance in the activity data resulted in highly significant differences in the main effects (line and age) but revealed no significance in the interaction. Activity scores (revolutions) for the H, C and L lines were 79234, 107987 and 124409, respectively for eight 22-h periods. Activity reached maximum levels at 56 days of age, then declined slightly. Within line phenotypic correlations between SC and activity and between SC and feed intake were significant throughout ages of testing only in the high line.