Regulation of Food Intake in Ruminants. 7. Interrelations Between Food Intake and Body Temperature

Temperature of goats maintained in metabolism stalls was monitored at several sites during oral, intraruminal, or false intraruminal feeding treatments to test the applicability of the thermostatic hypothesis of food intake regulation to ruminants. Temperature was nmnitored by thermistor probes in the hypothalamus, rectum, and rumen and on the horn, ear, and chest every 2 minutes, from 30 minutes before feeding to 90 minutes after feeding. Ruminal fluids were taken 4 minutes before feeding, at the end of a meal or 20 minutes after intraruminal and false intraruminal feeding, and at the end of 2-hour periods. Hypothalamic temperature increased at the time of feeding, irrespective of treatment, and also increased when ruminal fluid was sampled. Temperature at this location decreased when the goats lay down. Thus, it appeared that hypothalamic temperature was related to activity rather than to food consumption per se, the goats being more active during eating. There were no consistent temperature changes at any of the body locations that could be correlated with food consumption. Concentrations of ruminal aeetate, propionate, and total volatile fatty acids at the end of meals were not significantly (P < .10) higher than the respective concentrations before feeding. Ninety minutes after meals the concentrations of these rmninal metabolites