Metabolic response to feeding in the Chinese striped-necked turtle, Ocadia sinensis.

We measured oxygen consumption in juvenile Chinese striped-necked turtles (Ocadia sinensis) after they ingested food, either as a single meal or as double meals, to examine the influence of meal type and feeding frequency on specific dynamic action (SDA). Temporal variation in oxygen consumption after feeding was evident in the ingesting turtles but not in the unfed control turtles. In the single-meal experiment, the peak metabolic rate and the integrated SDA response (the whole energetic cost for the processes of digestion) both did not differ between turtles ingesting mealworms and shrimps when the influence of variation in ingested energy was removed, and the time to reach peak metabolic rate was not affected by meal type and the amount of food ingested. Turtles in the double-meal experiment ingested more energy and hence had a prolonged duration of SDA response than did those in the single-meal experiment, but the integrated SDA response did not differ between both experimental treatments when the influence of variation in ingested energy was removed. Our results show that meal type and feeding frequency have important consequences on the SDA response of juvenile O. sinensis. As the integrated SDA response remained remarkably constant either between turtles ingesting different food or between turtles ingesting the same food but at different frequencies when the influence of variation in ingested energy was removed, we therefore conclude that the energetic cost associated with ingestion is primarily determined by energy content of food ingested in juvenile O. sinensis.

Influence of food type on specific dynamic action of the Chinese skink Eumeces chinensis.

We used the Chinese skink (Eumeces chinensis) as an experimental model to study influence of food type on specific dynamic action (SDA) of feeding. Thirty-three adult males collected from a natural population were divided equally into three (one control and two experimental) groups. We starved all skinks at 30 degrees C for 3 days and then provided the experimental skinks with a single meal consisting of either mealworms or meat [the flesh of the bullfrog (Rana catesbeiana)]. Food ingested by skinks of the two experimental groups differed in lipid content and lean dry mass but not in total dry mass and energy. Defecation following feeding occurred slightly earlier in skinks ingesting mealworms (mean=41.7 h) than in those ingesting meat (mean=47.7 h), but the difference was not significant. Analyses of variance (ANOVAs) with repeated measures showed that temporal variation in oxygen consumption over 72 h after feeding was evident in the experimental skinks but not in the control ones. Oxygen consumption was higher in the experimental skinks than in the control ones during the time interval between 4.5 and 36 h after feeding. The peak metabolic rate was greater but occurred later in skinks ingesting meat than in those ingesting mealworms. The estimated amounts of oxygen consumed by mealworm-fed, meat-fed and unfed skinks at 30 degrees C over 72 h after feeding were 356.5, 393.8 and 295.2 mL, respectively. Our results provide a support for the previous prediction that SDA is affected by types of food ingested by animals as skinks ingesting mealworms and meat differed in the time to reach a peak metabolic rate, the level of the peak metabolic rate and the magnitude of the SDA effect.