Browsing by Author "Mmanda, Francis"

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    Climate-smart aquaculture in Tanzania: Assessment of transitional and heavy metals concentrations in a commonly used local feed ingredient for Tilapia farming
    (IJASRE, 2023-11) Vulla, Kelvin; Mmanda, Francis; Makule, Edna
    A study conducted from January through May 2023 to assess the concentrations of heavy and transitional metals in a commonly used local feed ingredient in a farmed Nile tilapia diet (Oreochromis niloticus) in Tanzania. Eleven fish feed ingredients such as, sunflower seed cake (SFSC), wheat pollard (WP), maize bran (MB), fish meal (FM), freshwater shrimp (FWS), cattle blood meal (CBM), bone meal (BM), soya bean meal (SBM), and rice bran (RB), brewers’ spent grain (BSG) and Taro leaves (Colocasia esculenta; TL) were randomly sampled from feed manufacturers, animal feeds’ centers and other animal feeds suppliers in Arusha and Dar es Salaam region for inclusion in this study. Heavy metals and transition metals in feed ingredients were analyzed using the Energy- Dispersive X-rays Fluorescence (XRF) (Xla Pro-Spectrometer/German) at the Tanzania Atomic Energy Commission (TAEC) laboratory. The results showed that most of the fish-feed ingredients used in this study comply with the maximum allowable concentrations in Nile tilapia diets-according to the Tanzania bureau of standards and the European commission. However, the results showed that, the concentrations of reported metals (As, Pb, Cd, Hg, Co, Cu, Mo, Mn, Ni, Ag, V, Cr, Fe and Zn) varied significantly (p < 0.05 ) in most of the analyzed local feed ingredients collected in Tanzania. The study has paved the way for other researchers to further assess more feed ingredients used not only on heavy metals but other potential contaminants in feeds to ensure sustainable fish farming in Tanzania.
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    Potential Application of Linear Programming Method and Solid-State Fermentation in Improving the Quality of Fish Feed and Profits of Small-Scale Nile Tilapia (Oreochromis niloticus) Farming in Tanzania
    (Wiley, 2026-01-30) Vulla, Kelvin; Mmanda, Francis; Makule, Edna
    The scarcity of affordable and high-quality fish feeds limits aquaculture development in many developing countries. The present study assessed the use of linear programming (LP) techniques for formulating Nile tilapia ( Oreochromis niloticus ) diets and solid- state fermentation (SSF) technology to improve their nutritional value. The formulated diets produced using LP and improved through SSF technology were analyzed for their chemical composition. The combined techniques enable the production of high- quality f ish feeds at low cost of 0.4 USD per kilogram. The resulting diets contained 36.2% of crude protein and 5.6% of crude lipid, and adequate minerals and essential amino acids and minerals align with Nile tilapia requirements. The fermented feeds provided optimum levels of lysine (15 g/kg), tryptophan (3.59 g/kg), and methionine-cysteine (11.25 g/kg), supporting healthy growth in juvenile tilapia. Overall, the model provides practical guidance for small-scale fish farmers and local feed producers in Tanzania to develop cost-effective, nutritionally balanced feeds.