Effect of Vegetable Tanning By-product on the Growth Performance of Caged Nile Tilapia (Oreochromis niloticus) as a Fishmeal Replacement

Abstract

The effect of vegetable tanning by-product (VTBP) on the growth performance of Nile tilapia (Oreochromis niloticus, Linnaeus) under cage culture system was evaluated. The chemical composition of vegetable tanning by-product (VTBP) and Fishmeal (FM) were analyzed. The dry matter (DM), crude protein (CP), ether extracts (EE) and ash content of VTBP were found 90.63, 77.02, 2.83 and 7.19%, respectively. The dry matter content of Fishmeal was recorded 87.3%. Ether extract content of Fishmeal (4.3%) was found slightly higher than the VTBP. The ash content of fishmeal was found 29.5%. But protein content of the Fishmeal (51.9%) was found much lower than the VTBP. Amino acid profile of both VTBP and Fishmeal were analyzed where the former showed higher amounts of some essential amino acids. The presence of aflatoxin in VTBP was found to be negative. The average temperature of pond water recorded during experimental period was 28.37, 27.69 and 28.64°C for treatment 1, 2 and 3 respectively. Dissolve oxygen level was similar to all the treatments and ranged from 6.1 to 6.7 ppm. The pH value was found between the ranges of 7.3 to 7.6. However, there was no significant difference among the survival rate, temperature, dissolved oxygen and pH. The fishes under various feeding treatments showed some difference in growth performance. The initial live weights of fishes were average 3 gm fish -1 . The fish productions in cage were 8.8 kg 10.2 kg 12.9 kg in treatment 1, 2 and 3 respectively. The production showed that treatment 3 significantly different from other treatments. Treatment 3 (VTBP) showed the highest production (12.9 kg/cage) and Treatment 1 obtained the lowest production (8.8 kg cage -1 ). Mean weight gain and daily weight gain of fishes also showed similar results where the highest value for Mean weight (177.6 ± 6.65 g) gain and Daily weight gain (2.9 ± 0.11 g) were recorded in treatment 3. The survival rate was more or less similar to all the treatments which were around 97%.