Influence of feeding pattern on energy balance and activity in rats

The effect of feeding pattern on energy balance and activity of rats was investigated with four treatment groups. Two groups were fed two meals per day at one of two levels (ad libitum or 1.25 times maintenance) and the other two groups were allowed to nibble either unrestricted or in 12 small meals per day. Four-day total collection digestion trials were conducted on individual rats. Pairs of rats were used for simultaneous activity and respiration calorimetry measurements. Meal-eaters gained less weight, digested and metabolized an approximately 4% greater fraction of their gross energy intake and had a 21% lower maintenance energy requirement. Ad libitum nibblers were about 23% more active during the average 24-hour period than high level meal-eaters, although this difference was not statistically significant. The energetic cost of activity as a percent of maintenance energy ranged from 60% to 18%. These estimates are higher than others in the literature and may have been affected by the activity measurements method, but indicate that differences in activity contributed to observed differences in energetic efficiency between meal-fed and nibbler rats.