Response of the digestive tract to low quality dry food in the fat jird (Meriones crassus) and the levant vole (Microtus guentheri)

Abstract

The ability to handle high and low quality diets was studied in the fat jird and levant vole. When fed a high quality diet (alfalfa hay), ‘zero time’ fermentation rates assessed by the rate of gases generated were 0·83 ± 0·20 and 0·69 ± 0·26 ml/gram caecum/h in the fat jird and levant vole respectively, and 0·96 ± 0·37 and 0·34 ± 0·14 ml/gram caecum/h respectively, when the two species were fed a low quality diet (Panicum grass). Maximal in-vitro fermentation capacity (assessed by the rate of gases generated), of the microbial population in caecal content of fat jirds and levant voles fed alfalfa hay was 2·09 ± 0·26 and 1·88 ± 0·79 ml/gram caecum/h respectively. When fed Panicum grass it amounted to 1·86 ± 0·16 and 0·89 ± 0·36 ml/gram caecum/h in the fat jirds and levant voles respectively. When fed alfalfa hay gastrointestinal tract mean retention time (MRT) was similar in both species. When fed Panicum grass MRT increased significantly by 65% in fat jirds, but was unchanged in the levant voles. Water electrolytes and volatile fatty acids (VFA) absorption along the large intestine in the levant voles maintained on the low quality diet, were reduced, but did not have a significant effect on absorption capacities of fat jirds. We suggest that the superiority of the fat jird over the levant vole in utilizing low quality feed is achieved by increasing mean retention time, maintaining fermentation rates and adequate VFA absorption.