Palatability and postprandial thermogenesis in dogs.

The role of palatability on postprandial thermogenesis was determined in six mongrel dogs of approximately 16 kg. Oxygen uptake (VO2) was continuously monitored by indirect calorimetry for 1 h before and 2 h after a standard meal of 1,390 kcal. In the first experiment each dog was given access to the meal, which was ingested within 5 min. In a second experiment the same meal was sham fed and collected into an esophageal pouch. In a third experiment the dogs were tube fed. In the first experiment a biphasic response was found in the postprandial increase in metabolic rate; a first phase lasting approximately 40 min and the other from 40 to 125 min. In the second experiment the increase in VO2 was comparable with that of the first experiment for the first 40 min but almost abolished for the remaining period; the sight and smell of food alone produced a similar effect. In the third experiment tube feeding caused a small increase in VO2, which was four times smaller than that found in both the first and the second experiment during the initial phase. However, during the second phase the increase in VO2 was comparable with that of experiment 1. An initial phase of feeding lasting approximately 40 min is identified with food palatability, whereas the second phase would correspond to a large extent to specific dynamic action of food.