Growth, feed utilization and nutrient digestibility in tilapia fingerlings (Oreochromis aureus Steindachner) fed diets containing bacteria-treated coffee pulp

The effectiveness of bacteria treated-coffee pulp (BT-CoP) in fish diets was evaluated in a feeding trial with Oreochromis aureus (Steindachner) fingerlings. Five diets were formulated to contain 0%, 6%, 12%, 18% and 24% BT-CoP, replacing wheat meal. Fish were reared in a recirculating unit consisting of 16 aquaria. Each aquarium was stocked with 10 fish of 1.1-2.4¿g. Fish were fed ad libitum twice daily (10 and 15¿h) for 4¿weeks. Fish fed diets without BT-CoP and with 6% BT-CoP showed similar growth (body weight, growth rate: RGRm) and feed utilization (feed conversion ratio, protein efficiency ratio, apparent net protein utilization). Diets containing 0% and 6% BT-CoP gave similar dry matter and protein digestibility coefficients, but dietary BT-CoP levels higher than 6% produced lower digestibility values, except for carbohydrate. It is concluded that O. aureus fingerlings may assimilate only small amounts (6%) of BT-CoP in the diets without adverse effects on growth and feed utilization parameters. The CoP-containing diets did not affect fish survival (100%). The depression in tilapia performance may be associated mainly with the high level of fibre present in the CoP diets.