Energy budget and reproductive performance of striped hamsters in response to variations in food quality

Abstract

The phenotypic plasticity of the digestive system is important to cope with the variations in food quality for wild small mammals, in particular for the lactating females because they must increase food intake to meet the highest energy requirements of offspring. This study aimed to investigate the energy budget and reproductive performance of striped hamsters (Cricetulus barabensis) fed on a high-fiber or high-fat diet across lactation. Body mass, food intake, resting metabolic rate (RMR), milk energy output (MEO), and litter size and mass were measured at peak lactation. The body composition, digestive enzymes activity, as well as the hypothalamus-driven gene expression relating to orexigenic or anorexigenic neuropeptides was determined at weaning. The food intake at peak lactation was not significantly changed in the females fed on a high-fiber diet, while it was decreased in those fed on a high-fat diet compared with the females fed a control diet. The females fed a high-fiber diet did not change RMR, but decreased MEO, and had smaller litters with lower masses. The females fed a high-fiber diet had a larger stomach, small and large intestine, and caecum, in parallel with increases in maltase and aminopeptidase activity, but these females did not show significant changes in amylase, lipase, lactase, or chymotrypsin compared with the females fed a control diet. The mRNA expression of AgRP was increased, and POMC was decreased in the hamsters fed a high-fiber diet compared with control ones. The high-fat group did not vary from the control group in almost all of the parameters. These findings suggest that the adaptive modulations in the digestive enzyme activity may be maximized at peak lactation, creating a hard limitation for SusEI in response to a high-fiber diet, which may be independent of either orexigenic or anorexigenic neuropeptides.