Effects of the physical form of the diet on food intake, growth, and body composition changes in mice

Authors: Yan, Lin; Combs, Gerald; Demars, Lana; JOHNSON, LUANN - University Of North Dakota

Submitted to: Journal of the American Association for Laboratory Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/10/2011
Publication Date: 7/20/2011
Citation: Yan, L., Combs, G.F., Demars, L.C., Johnson, L.K. 2011. Effects of the physical form of the diet on food intake, growth, and body composition changes in mice. Journal of the American Association for Laboratory Animal Science. 50(4):488-494.

Interpretive Summary: Laboratory animals are useful in obesity research. We compared the effects of physical forms of a diet (pellet vs. powdered) on food intake, growth, and adipogenesis in mice. We used two diets, a standard AIN-93G diet and a wheat-supplemented diet, and both diets were prepared in powder and pellets. In experiment 1, three-week-old mice were randomly assigned into 4 dietary groups consisting of the AIN-93G or the wheat-modified diet in either powdered or pelleted form. In experiment 2, mice were pair-fed the powdered diets to the level of food intake of those fed the pelleted form of the respective diets. The feeding period was 18 weeks for both experiments. Body weight, food intake, and fecal excretion were recorded, and body composition analysis was performed on conscious, immobilized mice 1 week before the termination of the experiment. Mice fed the powdered forms of either diet showed significantly greater increases in body weight in 2 weeks of feeding than mice fed the pelleted diets. In comparison to mice fed the pelleted diets, those fed the powdered diets also showed an approximately 85% increase in the ratio of fat mass:body mass, a two-fold increase in the ratio of abdominal fat weight:carcass weight. Powdered diet-fed mice also showed significantly greater plasma concentrations of insulin and leptin, and significantly lower plasma concentrations of adiponectin, than their pellet-fed counterparts. Food intake of mice fed the powdered diets were approximately 11% and 16% and total caloric intake were 14% and 17% greater for the AIN-93G and the wheat diets, respectively, than those of the pelleted diets. These results demonstrated that C57BL/6 mice responded to the physical form in which these diets are presented in terms of their food intake, which affected their growth, body composition and plasma concentrations of insulin and adipocytokines.

Technical Abstract: The present study investigated the effects of the rate of food intake on growth and adipogenesis in three-week old, male C57BL/6 mice. Mice were fed isocaloric diets (AIN-93G or a modification containing 25% wheat) presented in either powdered or pelleted form. In experiment 1, mice were randomly assigned into 4 dietary treatment groups consisting of the AIN-93G or a wheat-modified diet in either powdered or pelleted form. In experiment 2, mice were pair-fed the powdered diets to the ad libitum level of food intake of those fed the pelleted form of the respective diets. The feeding period was 18 weeks for both experiments. Body weight, food intake, and fecal excretion were recorded, and body composition analysis was performed on conscious, immobilized mice 1 week before the termination of the experiment. Mice fed the powdered forms of either diet showed significantly greater increases in body weight in 2 weeks of feeding than mice fed the pelleted diets (P = 0.01). In comparison to mice fed the pelleted diets, those fed the powdered diets showed an approximately 85% increase in the ratio of fat mass:body mass, a two-fold increase in the ratio of abdominal fat weight:carcass weight. Powdered diet-fed mice also showed significantly greater plasma concentrations of insulin and leptin, and significantly lower plasma concentrations of adiponectin, than their pellet-fed counterparts. Food intake of mice fed the powdered diets were approximately 11% and 16% and total caloric intake were 14% and 17% greater for the AIN-93G and wheat diets, respectively, than those of the pelleted diets. These results demonstrated that C57BL/6 mice responded to the physical form in which these diets are presented in terms of their food intake, which affected their growth, body composition and plasma concentrations of insulin and adipocytokines.