食物类型对红耳滑龟幼体摄食特殊热动力作用的影响

Influence of food types on specific dynamic action of feeding in hatchling red-eared slider turtles Trachemys sripta elegans

We used hatchling red eared slider turtles Trachemys sripta elegans to study the influence of food types on specific dynamic action (SDA) of feeding. A total of 27 turtles were purchased in July 2003 from a private hatchery operator in Hangzhou, and were equally assigned into three groups, two experimental and one control. Body mass of our turtles varied from 7 3 to 9 0 g, and the mean values did not differ among groups. After fasting all turtles for 3 days at 30℃, we provided the experimental turtles with a single meal, consisting of either mealworms (larvae of Tenebrio molitor ) or commercial shell free shrimps. Turtles feeding on mealworms consumed less food than did turtles feeding on shell free shrimps in terms of quantity, whereas turtles of both experimental groups did not differ in food intake in terms of energy. Defecation occurred earlier in turtles feeding shell free shrimps (mean = 40 3 h) than in turtles feeding mealworms (mean = 46 4 h). Turtles were housed individually in a 300 ml closed respiratory chamber, and oxygen consumption was measured at 0, 4 5, 10 5, 16 5, 22 5, 33, 45, 57 and 72 h since the start of our experiment. Temporal variation in oxygen consumption was found in experimental turtles but not in control turtles, suggesting that feeding exerts an effect on metabolic rate (and thus, SDA) in T. s. elegans . Turtles of both experimental groups consumed significantly more oxygen than did control ones during the period between 4 5 and 33 h since feeding. The mean time to reach a peak SDA was 10 2 h for turtles feeding mealworms and 18 0 h for turtles feeding shell free shrimps. The height of SDA peak did not differ between turtles feeding the two different types of food. A two way ANOVA, with food type and measuring time as the factors, showed that changes in metabolic rate following feeding were affected by the food type but not by the food × time interaction. Our study adds evidence that animals feeding different food differ in SDA When comparing our data with the corresponding data reported for other species, we find that the time to reach a peak of SDA, duration of SDA and the height of SDA peak differ considerably among species.