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Kansas State University (1987)

The effects of moisture content and metabolic water production on desert rodent seed preferences

Frank, Craig L.

Titre : The effects of moisture content and metabolic water production on desert rodent seed preferences

Auteur : Frank, Craig L.

Université de soutenance : Kansas State University

Grade : Master of Science (MS) 1987

Résumé
Kangaroo rats (family Heteromyidae) are primarily granivores. These desert rodents do not drink free water, they instead depend upon preformed water in their diet and the water produced by the oxidation of food (metabolic water). The oxidation of different nutrients produces different net amounts of metabolic water. At low humidities, oxidizing carbohydrates produces a net metabolic water gain whereas lipid metabolism requires the investment of more water than is produced, resulting in a net water loss. Protein metabolism produces a severe water loss, mainly through urination. Under humid conditions, carbohydrate metabolism again produces a net water gain, and although slightly reduced, protein metabolism still results in a large water loss. Lipid oxidation at high humidities, however, produces a large net metabolic water gain. Diet composition therefore influences heteromyid water balance and accordingly may also affect diet choice. Preference experiments involving semi-synthetic diets were conducted to determine the influence of net metabolic water production on the diet preferences of Dipodomvs spectabilis. Results indicate that at low humidities, kangaroo rats in a positive water balance prefer : 1) intermeadiate protein, 2) high lipid, and 3) high carbohydrate diets. When water stressed, the rodents prefer low protein diets and the preference for high lipid diets decreases. At high humidites, the rodents always prefer high lipid diets. These results indicate that kangaroo rats usually prefer diets that produce the greatest net metabolic water gain, regardless of energy content.

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