Effects of feeding detoxified rubber seed meal on growth performance and haematological indices of Labeo rohita (Hamilton) fingerlings

• Rubber seeds are the good source of protein, however they contain toxic substances.
• Toxicants need to be removed to use it as an alternative source of dietary protein supplement in the aquafeed.
• Economical ways of detoxification can remove 85% of the toxicant.
• Up to 200 g of detoxified rubber seed meal could be incorporated in 1 kg diets of Labeo rohita fingerlings without compromising the growth response and health status in terms of haematological indices.

A feeding trial was conducted for 60 days to study the effect of detoxified rubber seed meal as protein source in the diet of Labeo rohita fingerlings on growth performance and haematological indices. One hundred and eighty fingerlings (22.5 ± 7.7 g) were equally distributed in four experimental groups having three replicates each. The experiment was conducted in FRP tanks of 500 L capacity each and temperature range was 22.6–28.5 ̊C. Four isoproteinous (329.9–323.1 g/kg) and isocaloric (17.0–18.0 MJ/kg) diets were prepared with detoxified rubber seed meal incorporated at the level of 0 g/kg (control diet), 100 g/kg (diet T1), 200 g/kg (diet T2) and 300 g/kg (diet T3) of diet. The growth parameters such as weight gain, feed conversion ratio (FCR), protein efficiency ratio (PER), specific growth rate (SGR) and survival rate were monitored in the study period. Blood samples were collected to determine the different haematological indices like total red blood cells count, white blood cells count, packed cell volume, haemoglobin concentration, mean corpuscular volume, and mean corpuscular haemoglobin concentration. The water quality parameters were maintained within the optimum range. Control, T1 and T2 group showed significantly (P < 0.05) higher growth performance in terms of biomass gain, FCR and SGR as compared to T3 groups. Haematological parameters like PCV were significantly better (P < 0.05) in C and T1 groups as compared to T3. However, haemoglobin content of control, T1 and T2 groups were significantly (P < 0.05) similar. Based on the findings up to 200 g of detoxified rubber seed meal could be incorporated in 1 kg diets of L. rohita fingerlings without compromising the growth response and health status in terms of haematological indices.