Dietary inclusion of non-conventional palm kernel meal enhances growth, digestive enzyme activities and carcass characteristics of juvenile rohu (Labeo rohita)

A 60-day feeding trial was performed to test the nutritional value and utilization possibility of palm kernel meal (PKM) as a feed ingredient for juvenile Labeo rohita. Five iso-nitrogenous diets were prepared with various inclusions of PKM which replaced sunflower oil cake and de-oiled rice bran namely, control (without PKM), T1 (50 g/kg PKM), T2 (100 g/kg PKM), T3 (150 g/kg PKM) and T4 (200 g/kg PKM). The experiment was conducted in 350 L fibre reinforced plastic tanks in triplicate and each tank stocked with twenty-five juvenile rohu (7.2 +/- 0.01 g) were fed twice daily at 5% of body weight with the experimental diet. The growth performance values showed a higher overall linear trend in T2 and it is significantly different from control as well as T1 groups. Final results showed highest average body weight, specific growth rate, protein efficiency ratio, and apparent net protein utilization in a dose-dependent manner (p < 0.05). Significantly higher amylase, protease, and lipase activities were recorded in T2 treatment (p = 0.003, p = 0.001 and p = 0.002, respectively). Additionally, dietary PKM significantly lowered the aspartate amino transferase, alkaline amino transferase and alkaline phosphatase enzyme activities in a dose-dependent manner (p < 0.05). Significantly higher lactate dehydrogenase, malate dehydrogenase, superoxide dismutase and catalase activities in the liver tissues were recorded in T4 (p = 0.004, p = 0.01 and p = 0.02 and p = 0.001, respectively). Based on the polynomial regression analysis, the PKM inclusion at 26.17-100.11 g/kg can be effectively used in the diet of juvenile L. rohita as a non-conventional growth-promoting feed ingredient without any harmful effects on its growth performance and physiological activities.