The effect of dietary macronutrient composition on specific dynamic action (SDA) in southern catfish Silurus meridionalis Chen juveniles (39.0

In previous growth experiments with carnivorous southern catfish (Silurus meridionalis), the non-fecal energy lose was positively related to dietary carbohydrate level. To test whether metabolic energy expenditure accounts for such energy loss, an experiment was performed with southern catfish juveniles (33.2–71.9 g) to study the effect of dietary carbohydrate level on fasting metabolic rate and specific dynamic action (SDA) at 27.5 ℃. The fasting metabolic rate in this catfish was increased with dietary carbohydrate level, and the specific dynamic action (SDA) coefficient (energy expended on SDA as percent of assimilated energy) was not affected by dietary carbohydrate level. The results suggest that in southern catfish, carbohydrate overfeeding increases metabolic rate to oxidize unwanted assimilated carbohydrate. A discussion on the poor capacity of intermediate metabolism for adapting dietary carbohydrate in carnivorous fish and its possible relationship with facultative component of SDA was also documented in this paper.

etabolic response was investigated in southern catfish Silurus meridionalis at 27.5℃. The results showed that there was no significant difference in the specific dynamic action (SDA) coefficient among the groups of different feeding levels (P >0.05). The duration increased from 26.0 to 40.0 h and the peak metabolic rate increased from 207.8 to 378.8 mg O2 kg-1 h-1 when the feeding level was increased from 0.5 to 4%. The relationship between the peak metabolic rate (RP, mg O2 kg-1 h-1) and FL could be described as: RP =175.4 t 47.3 FL (r2 = 0.943, n = 40, P < 0.001). The relationship between the SDA duration (D, h) and FL could be described as D=30.97FL0.248 (r2=0.729, n=40, P < 0.001).