DIRECT-FED MICROBIALS AS A GROWTH ENHANCER OF GENETICALLY MALE NILE TILAPIA FRY (GMT) (OREOCHROMIS NILOTICUS L.)JOSEPH G. CAMPANG AND EMMANUEL M. VERA CRUZ
This experiment was conducted to evaluate the growth and survival of Genetically Male Nile Tilapia (GMT) (Oreochromis niloticus) fry fed with commercial diet (CF) supplemented with different inclusion levels of Direct Fed Microbials (DFM) under aquarium rearing condition. The treatments evaluated were: Treatment I (control), Treatment II (1 g DFM/kg + commercial feed (CF), Treatment III (5 g DFM/kg + CF, and Treatment IV (10 g DFM/kg + CF). Growth, survival and feed conversion ratio of the GMT were monitored after six weeks of feeding. Results indicated significantly better growth of fish fed with diet supplemented with 5 g and 10 g DFM/kg of feed, respectively compared with the control and 1 g DFM/kg of feed, in terms of specific growth rate (SGR; P < 0.01), absolute growth rate (AGR; P < 0.05) and survival rate (SR) (P < 0.01). The GMT fed 5 g and 10 g DFM recorded the highest survival rate at 95% and 93.33 %, respectively and were significantly higher than those fed 5 g DFM and control diet with a common mean value of 89%. Water parameters such as dissolved oxygen, temperature, pH, total alkalinity, total hardness, and total NH3-N were within the acceptable range for GMT culture. However, significant difference on total NH3-N concentration of water (P < 0.01) was observed. Lowest NH3-N concentration in the aquarium was recorded in fish fed 10 g DFM/kg of CF at 0.18 mg/L only while highest concentration occurred in the control treatment of 0.71 mg/L apparently indicating the NH3 suppressing ability of DFM through the feces and urine.
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