Feeding higher level of de-oiled rice bran causes stress to Labeo rohita fingerlings

A 60-day feeding trial was conducted with different inclusion levels of de-oiled rice bran (DORB) to study the digestive enzyme activity, physio-metabolic changes and oxidative stress in Labeo rohita fingerlings. Six iso-nitrogenous (30% crude protein), iso-lipidic (6% crude lipid) and iso-energetic (380.14 Kcal/100 g) semi-purified diets were prepared with the graded levels of DORB viz. 0 (control), T20 (20%), T30 (30%), T40 (40%), T50 (50%) and T60 (60%). Three hundred and fifteen (315) fingerlings with an average weight of 8 ± 0.5 g were distributed randomly in seven treatments in triplicates, following a completely randomised design (CRD). The digestive enzyme, protease and amylase activities were higher in 20, 30 and 40% DORB fed groups but the Lipase activity did not vary significantly whereas, SOD and GST activity was significantly lower (p < 0.05) in the same groups. The T50 and T60 groups showed significantly higher (p < 0.05) hepatic LDH (Lactate dehydrogenase), GST (Glutathione-s-transferase) and SOD activity, while RBC (Red blood cell) and WBC (White blood cell) content were found significantly lower in these groups. The catalase activity did not vary significantly (p > 0.05) among treatment group. Serum glucose content was higher in the T40, T50 and T60 groups, while serum total protein, albumin, NBT (Nitroblue tetrazolium) and haemoglobin levels were not significantly different among the treatments. From the study, it can be concluded that DORB causes stress to fish when fed at higher inclusion level (50 & 60%).