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ABSTRACT12-week feeding trials were conducted to evaluate the nutritive value of two forms of palm cull date and date pits as energy sources, supplemented with feed additives (Phytogenics), to be partially replaced (13.5%) yellow corn in feeding Nile tilapia fingerlings. Twelve experimental isonitrogenous (30.43% crude protein), isocaloric (436.43 kcal GE 100g-1) experimental diets were formulated taking into account energy sources and feed additives. Concerning energy source, four experimental diets were formulated which contain: yellow corn (YC) as control diet, dried cull date (DCD), wet cull date (WCD) and date pits (DP). As for feed additives (flavorings), three dietary sub-groups were builtup in each group to include: zero additives, 0.03 % Digestarom® (DG) and 0.03 % Marjoram leaf extract (MLE). Ten fingerlings (10.55 ± 0.30 g) were stocked/aquarium; two replicates per treatment and fed twice daily (six days) at 3% of body weight for 84 days.The results indicated that the partial replacement (13.5%) of WCD instead of YC supplemented with or without feed additives increased fish specific growth rate and feed utilization. However, replacement either DCD or DP decreased tilapia performances; meanwhile DP recorded the worst values. On the other hand, DG supplementation improved fish performances either fed WCD-based diets or control diets (YC). It could be concluded that wet cull date may be cost-effective when partially replaces yellow corn in tilapia diets as energy source, and improves fish performances when supplements with 0.03 % Digestarom®.

Twelve experimental diets containing 35% crude protein and 434.29 Kcal gross energy 100g-1 were formulated to process three groups of diets according to protein source and level: group 1 (G1) consists of: 25% fish meal (FM) + 75% soybean meal (SBM); group 2 (G2): 50% FM + 50% SBM and group 3 (G3): 75% FM + 25% SBM. Each group included four treatments according to feed additive source and level: a) control diet (without garlic or onion: D1, D5, D9), b) supplemented with 4% garlic (D2, D6, D10), c) supplemented with 6% onion (D3, D7, D11) and d) supplemented with 10% mixture (4% garlic and 6% onion: D4, D8, D12) on dry matter basis as phyto additives in order to study its effects on growth performance, feed utilization and whole body composition of Nile tilapia (Oreochromis niloticus) mono-sex fingerlings. Fish were reared in thirty six glass aquaria for 84 days, triplicate per treatment. Ten fingerlings of tilapia were placed per each aquarium with an average initial weight of 3.12 ± 0.3 g/fish. Fish were fed twice daily (six days a week) at a daily feeding rate of 5 % of live body weight on dry matter basis until the end of the trial. The results illustrated that the best growth performance values (weight gain; average daily gain, ADG; specific growth rate, SGR%) and feed utilization (feed intake, FI; feed conversion ratio, FCR; protein productive value, PPV% and energy utilization, EU) were significantly (P<0.05) realized with fingerlings fed G2 diet followed by that fed G3 diet and then that fed G1 diet, respectively regardless of type and level of phyto additives. On the other hand, addition of 10% mixture of garlic and onion as phyto additives significantly (P<0.05), increased growth performance, feed and nutrient utilization rather than solitary addition of either garlic or onion, regardless of protein source and level which clearly showed with fingerlings fed D8 diet. Furthermore, no significant differences (P0.05<) were observed in feed and nutrient utilization between fingerlings fed additive mixture diet (Gg+o) and control diet (Gc) in spite of the lowest feed intake recorded for the later group (70.55 g/fish). Taking into account the diet number, which reflects the interacted effect of both protein source and level beside phyto additives source and level, it was found that fingerlings fed diet D8 realized the best growth performance followed by diet D12. On the other hand, fingerlings fed D5 and D8 realized the higher values for protein efficiency ratio (PER), protein productive value (PPV %), energy utilization (EU %) and the best feed conversion ratio (FCR). Furthermore, the results illustrated also that fingerlings fed onion supplemented diets recorded better growth performance response than those fed supplemented diets or control diets, and fingerlings fed onion and garlic mixture supplemented diets showed better growth performance and feed utilization than any of them in the same protein combination group. It could be concluded that diets consist of 50% FM + 50% SBM with 10% mixture of garlic and onion as phyto additives in Nile tilapia (O. niloticus) mono-sex fingerlings diets, are considered ideal for optimal growth and feed utilization without any adverse effect on fish health.

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