Substitution of organic manure for pelleted feed in tilapia production.
The partial substitution of organic manure for pelleted feed in monosex Oreochromis niloticus (20 000/ha) production ponds was studied in Honduras. Treatments were: pelleted feed only (23% protein; 3% fish biomass/day), organic manure (chicken litter 1000 kg total solids (TS)/ha weekly) only during the first 60 days, followed by pelleted feed only, and organic manure (chicken litter 500 kg TS/ha weekly) and pelleted feed (1.5% fish biomass/day) given simultaneously. Mean gross yields after 151 days were 5305, 4794 and 4351 kg/ha for treatments 1 to 3, respectively. At harvest, fish averaged 262, 284 and 251 g/fish, respectively. No differences were detected among treatments for gross yield or average individual weight. Feed conversion ratio for treatment 1 (1.83) was significantly greater than for treatment 3 (0.95). It was concluded that layer chicken litter can replace 27 to 58% of pelleted supplemental feed without significantly affecting tilapia yield. Total production costs from enterprise budgets were US $5336/ha (feed only), $4645/ha (manure followed by feed), and $3471/ha (manure and feed simultaneously).