Growth Performance of Nile Tilapia (Oreochromis niloticus) Fed with Diets Containing Different Levels of Hydrolysable and Condensed Tannin

This study was undertaken to evaluate the effect of hydrolysable tannin (HT) and condensed tannin (CT) on growth performance and body composition of Nile tilapia. Hydrolysable tannin and CT were included into diets at four levels (0, 5, 15, and 25 g kg-1 diet). The diet with zero tannin level acted as control and the response of fish fed diets containing tannin was compared to that of the control diet. All the diets were iso-nitrogenous and iso-energetic. Hydrolysable and condensed tannin had a significant (P<0.05) effect on body weight gain (WG), feed intake (FI), feed conversion ratio (FCR), specific growth rate (SGR) and protein efficiency ratio (PER). Weight gain, SGR and PER of fish fed on the diets containing 15 and 25 g HT/ kg diet were significantly (P< 0.05) lower than those fed on the other diets. Feed conversion ratio of fish fed diets containing 15 and 25 g kg-1 HT were significantly (P<0.05) higher than those fed on the other diets. Feed intake of fish fed diets containing 15 and 25 g HT/kg diet were significantly (P< 0.05) lower than those fed on the other diets, except for diet containing 15 g kg-1condensed tannin (CT2). It is concluded that adverse effect of HT is higher on tilapia compared to that of CT and that protein sources of plant origin containing high amounts of tannins, in particular HT, should be used with caution as fish meal substitutes in tilapia diets.