Effect of purified macronutrients on specific dynamic action in carnivorous southern catfish
2007
FU, S.J. | CAO, Z.D. | PENG, J.L.
The effect of purified macronutrients on specific dynamic action (SDA) was assessed in juvenile southern catfish (39.81 ± 1.35 g) at 27.5 °C by stuffing iso-energetic (5 kJ) casein, corn oil, corn starch in sections of grass carp intestine (0.25 g). A control (without filler) and mixed diets were also made (each macronutrient provide one-third energy). The postprandial metabolic response, i.e. the oxygen consumption curve, was markedly different among fish fed different food. The peak postprandial metabolic rate of fish fed mixed diet (76.7 mgO₂ h⁻¹) was significantly higher than that of protein group (66.1 mgO₂ h⁻¹), while the latter was significantly higher than those of other groups (56.1 mgO₂ h⁻¹ for lipid, 54.0 mgO₂ h⁻¹ for carbohydrate and 56.1 mgO₂ h⁻¹ for control) (P < 0.05). The SDA durations were 32, 32, 30, 14 and 10 h for mixed, casein, corn oil, corn starch and control groups, respectively. The SDA coefficient (energy expended on SDA as per cent of ingested energy) of casein (9.41%) was significantly higher than that of mixed diet (7.43%) (P < 0.05), while the latter was significantly higher than those of corn oil (3.97%) and corn starch (0.84%) (P < 0.05). The results of this study suggested that the method of using casing on investigation of SDA in carnivorous fish was feasible. The SDA response of carnivorous southern catfish fed protein was higher than lipid while latter was higher than carbohydrate (nearly to zero). The result of this study may give interesting information for understanding the physiological mechanism under SDA.
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