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Abstract
A sixty day long experiment was conducted to evaluate the growth enhancing effect of saponin in Nile Tilapia, Oreochromis niloticus in hapas. There were 5 different diets (30 % protein) containing 0, 150, 300, 500 and 1000 mg/kg saponin designated as diet 1, 2, 3, 4 and 5 respectively. Each dietary treatment had three replicates each with 50 fish. All the fish were of same age group and mean initial weight was 2.25±0.03 g. At the beginning of the experiment, fish were fed three times daily at the rate of 10% body weight and subsequently the feeding rate was reduced to 8% and 6% body weight daily. Results on growth performance of fish showed that Tilapia attained the significantly (P< 0.05) higher growth in dietary treatment 2 (S 150) and 3 (S 300) respectively. The mean specific. growth rate (SGR % day) values ranged between 3.37 and 3.59 and mean food conversion ratio (FCR) values ranged between 1.77 to 2.04 with dietary treatment 2 and 3 resulting the lower FCR. Diet 2 and 3 had significantly (P<0.05) higher PER (1.93 and 1.95 respectively) and ANPU values (32.78 and 34.42 respectively). The lowest gonado-somatic index (GSI) for male and female were found in those fishes fed diets supplemented with the highest doses of saponins. The GSI of males were much lower than that of females. The females in control group showed the highest GSI values. Hepato-somatic index (HIS) were more or less similar females than the males. There were no significant (P< 0.05) differences in the GSI and HIS values of fishes in different dietary treatments. Significantly (P< 0.05) the highest relative gut mass (RGM) value was found in fish fed diet 3. The results of the present investigation demonstrated that a feed supplemented with lower doses of saponin (150 or 300 mg/kg) significantly increased the growth of Nile Tilapia compared to the control.