Substitution of soybean meal with fermented Jatropha kernel meal: effect on growth performance, body composition, and metabolic enzyme activity of Labeo rohita

A 60-day feeding trial was conducted to evaluate the nutritional potential of fermented Jatropha kernel meal (FJKM) in the diets of rohu, Labeo rohita, fingerlings. Four iso-nitrogenous (336 g kg−1) and iso-energetic (20 MJ kg−1) diets containing 0, 100, 200, and 300 g kg−1 FJKM in replacement of 0, 33.3, 66.7, and 100% soybean meal protein, respectively, were prepared and designated as control, T1, T2, and T3, respectively. A total of 180 acclimatized fish (average weight 6.05 ± 0.04 g) were equally distributed into four experimental groups in triplicates, and were fed their respective diets to satiation twice daily at 10:00 h and 18:00 h. Higher percent weight gain (%WG); specific growth rate (SGR); protein efficiency ratio (PER); protease, aspartate amino transferase (AST), and alanine amino transferase (ALT) activities; and lower feed conversion ratio (FCR) were recorded in T2 and T3 groups compared to other groups. Whereas hepatosomatic index (HSI), intestinal somatic index (ISI), and amylase, lactate dehydrogenase (LDH), malate dehydrogenase (MDH), superoxide dismutase (SOD), and catalase activities among the various dietary groups did not vary significantly (P > 0.05). Whole body composition of fish analyzed at the end of the feeding trial exhibited significantly (P < 0.05) higher ether extract and lower crude protein in the control group compared to the FJKM-fed groups. These results indicated that rohu fingerlings can efficiently utilize FJKM without any detrimental effect on growth performance, nutrient utilization, and metabolic response.