title: Supplemental effects of mixed ingredients and rice bran on the growth performance, survival and yield of Nile tilapia, Oreochromis niloticus reared in fertilized earthen ponds.
abstract: Unaffordability of commercial feeds to semi-intensive Nile tilapia, Oreochromis niloticus farmers has led to reliance on supplemental feeding and fertilization for nutrition of their fish without a scientific basis. This study compared the growth, survival, condition factor and yield performance of O. niloticus fed on mixed ingredients (MI) and rice bran alone (RB) diets reared in fertilized earthen ponds in small scale farmers' ponds. The study also determined phytoplankton composition, biomass and abundance in the experimental ponds. Quadruplicate ponds were stocked with O. niloticus and African sharptooth catfish, Clarias gariepinus at a stocking ratio of 1:3. The initial mean weights of O. niloticus and C. gariepinus were 14.62 ± 0.61 and 20.34 ± 1.44 g respectively. The fish were fed on MI and RB diets with protein content of 184.74 and 126.06 g kg(-1) respectively for 270 days. The results showed that growth performance, survival rate and condition factor of O. niloticus were not affected by either feeding with MI or RB diet (p > 0.05). Moreover, there were no significant differences obtained in phytoplankton biomass and abundance in O. niloticus ponds fed on the two diets (p > 0.05). Furthermore, feeding O. niloticus either on MI or RB diet did not affect the net and gross fish yields (p > 0.05). The study revealed that the use of either MI or RB diet does not significantly affect the performance of O. niloticus cultured in semi-intensive earthen ponds where natural food organisms are an integral part of the culture system. Rice bran could be used for semi-intensive culture of O. niloticus in fertilized ponds to boost the production based on its availability and low cost.
authors.affiliation: Department of Aquatic Sciences and Fisheries, University of Dar es Salaam, P. O. Box 35064, Dar es Salaam, Tanzania ; Department of Biology, School of Life Sciences, East China Normal University, Shanghai, China.
authors.forename: S M
authors.initials: SM
authors.lastname: Limbu
authors.affiliation: Tanzania Fisheries Research Institute, Headquarters, Dar es Salaam, Tanzania.
authors.forename: A P
authors.initials: AP
authors.lastname: Shoko
authors.affiliation: Department of Animal Science and Production, Sokoine University of Agriculture, Morogoro, Tanzania.
authors.forename: H A
authors.initials: HA
authors.lastname: Lamtane
authors.affiliation: Tanzania Fisheries Research Institute, Headquarters, Dar es Salaam, Tanzania.
authors.forename: M A
authors.initials: MA
authors.lastname: Kishe-Machumu
authors.affiliation: Kilombero District Council, Ifakara, Morogoro, Tanzania.
authors.forename: M C
authors.initials: MC
authors.lastname: Joram
authors.affiliation: Tanzania Fisheries Research Institute, Kigoma Centre, Kigoma, Tanzania.
authors.forename: A S
authors.initials: AS
authors.lastname: Mbonde
authors.affiliation: Tanzania Fisheries Research Institute, Kigoma Centre, Kigoma, Tanzania.
authors.forename: H F
authors.initials: HF
authors.lastname: Mgana
authors.affiliation: Department of Aquatic Sciences and Fisheries, University of Dar es Salaam, P. O. Box 35064, Dar es Salaam, Tanzania.
authors.forename: Y D
authors.initials: YD
authors.lastname: Mgaya
keywords: Mixed feed ingredients; Oreochromis niloticus; Phytoplankton; Rice bran; Semi-intensive culture