Effect of dietary tannin on growth and haemato-immunological parameters of Labeo rohita (Hamilton) fingerlings

A feeding trial was conducted for 60 days to determine the effect of dietary tannin on growth and health status of Labeo rohita fingerlings. One hundred and eighty fingerlings (average weight 3.2 g) were randomly distributed into six treatment groups with three replicates each. Six isonitrogenous (crude protein 339.8-351.1 g/kg feed) and isocaloric (16.51-16.65 MJ DE/kg) practical diets were prepared with graded levels of tannin, viz. control, T1 (2.5 g/kg), T2 (5 g/kg), T3 (10 g/kg), T4 (15 g/kg) and T5 (20 g/kg). Addition of tannin up to 20 g/kg did not affect the weight gain (%), specific growth rate, feed conversion ratio, protein efficiency ratio, and apparent net protein utilization of fingerings significantly (P>0.05). The hepato somatic index value of control group was lowest than the other experimental groups. The muscle cholesterol level and haemoglobin count in the different treatments was significantly increased compared with the control. The immunological parameters like total leucocyte count and respiratory burst activity was significantly increased in tannin-fed groups. Based on the results of the present study, it is concluded that short-term feeding for 60 days of hydrolysable tannin has no adverse effect on growth of L. rohita fingerlings. Hence feeding of hydrolysable tannin on a long-term basis needs further study.