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The study was conducted to develop practical diets in Tanzania for Nile tilapia using
fish meal (FM), soybean meal (SBM), cotton seed meal (CSM), sunflower seed meal
(SFSM), freshwater shrimp meal (FSM) and blood meal (BM). Eleven isonitrogenous
(30g 100g-1), isolipidic (10g 100g-1) and isoenergetic (18 kJg-1) test diets were prepared;
the control diet (FM) used FM (22%) and SBM (30%) as the major sources of protein.
In the test diets, FM was fixed at 5%, while inclusion of SBM, CSM and SFSM varied
as follows; SBM diets contained SBM at 20(SBM20), 25(SBM25) and 30(SBM30).
CSM diets contained CSM at 15(CSM15), 20(CSM20) and 25(CSM25) and SFSM diets
contained SFSM at 10(SFSM10), 15(SFSM15) and 20(SFSM20). Blended diet
(BLEND) contained CSM and SFSM at 10% and SBM at 5%. Chemical composition
was determined using standard method (AOAC, 2002). A total of 330 fingerlings with
an average weight of 3.5 g were stocked at rate of 10 fish per 20 L tank. Dietary
treatments were in triplicates in complete randomized design. Fish were fed for eight
weeks and once a week were weighed and ration adjusted accordingly. Collected data
was analysed using descriptive statistics and one way ANOVA at p<0.05. SBM, CSM,
SFSM, FSM and BM had 42.3/44.6/19.5/59.1/83.1% of CP and 11.9/14.4/35.5/7.0/0.20%
of CF respectively. There was no significant difference in growth between FM and
CSM diets (p<0.05). Higher growth was observed in CSM diets and least in SFSM
diets. Optimum growth for each ingredient was observed at CSM20, SBM25 and
SFSM20. Feed utilization followed the same trend. SFSM, BLEND and CSM diets
were cost-effective than FM and SBM diets (p<0.05). Long-term feeding trials using the
BLEND, CSM20, SBM25 and SFSM20 diets should be done to evaluate their
biological and economical performance under actual farming conditions. |
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