Short-term starvation at different feeding regimes on appetite responses, feeding utilization and physiological indices, of red hybrid tilapia (Oreochromis mossambicus × Oreochromis niloticus) fingerlings reared in brackish water.

A 42 day factorial trial (3x2) was designed to evaluate the effect of short-term starvation with different feeding frequencies on performance, feed utilization, physiological status and appetite responses of red hybrid tilapia fingerlings. Eighteen plastic tanks with a capacity of (55 L) were used to accomplish this work. Fingerlings with an average initial weight of 23 g ± 0.2 (SE) were randomly stocked at a rate of 8 fingerlings/aquarium. Six groups were designated as the following: II/ED: fish was fed twice every day; IV/ED: fish fed four times every day; II/EOD: fish fed twice every other day (alternate-day feeding or one day of feeding followed by another of fasting); IV/EOD: was fed four times every other day; II/EO3D: fish fed twice every other three days (three day of feeding followed by another of fasting) and IV/EO3D: fish fed four times every other three days. Fish were fed on commercial diets 30 % protein (4 % of biomass). Results showed insignificant differences between fish fed every other day and those fed every day in some growth indicators. In the same trend, the interaction between feed deprivation and feeding frequency cleared that fingerlings of IV/EOD did not significantly differ with those fed every day in growth indices. Moreover this treatment was the best in feed conversion efficiency and several physiological indicators.

Evaluation of fermented soybean meal by Bacillus subtilis as an alternative to fishmeal on the growth, and physiological status of Nile tilapia Oreochromis niloticus fingerlings.

A feeding trial was conducted to investigate the effect of fermented soybean meal with Bacillus subtilis bacteria on growth performance, feed utilization, carcass composition, and hematological, and histological section of the liver and intestine of Nile tilapia Oreochromis niloticus fingerlings. Commercial soybean meal (SBM) containing 44% Crude Protein (CP) was fermented using the solid-state fermentation method which depended on autoclaving of SBM, then bacterial treatment injection by Bacillus subtilis, and finally incubation at 40C for 72 h then autoclaved to stop the growth of bacteria. Five isonitrogenous (25% crude protein) and isocaloric (4.4 kcal\g gross energy) experimental fish meal-free diets were formulated to compare with a common control diet containing fishmeal and unfermented soybean meal. Diets without fish meal contain fermented soybean meal (FSM) as a sole protein, FSM with corn gluten (CG), FSM with free amino acid methionine (Meth), FSM with corn gluten and methionine, and unfermented soybean meal. Eighteen glass aquaria, 80-L net volume, were used to stock 10 fingerlings (10.0 ± 0.1 g/fish) in each aquarium in the replicates group. The feed amount was given three times daily, six days a week throughout the 98 days experimental period. Fish were weighed biweekly and feed amounts were adjusted based on the new fish weight. Bacterial fermentation enhanced the protein content of commercial soybean meals by 6%. The crude protein of fermented soybean meal increased from 43.44% to 50.67%. Used of FSM as a sole dietary protein source resulted in a decrease in growth rate and feed utilization. However, the incorporation of FSM with corn gluten, and/or methionine amino acid led to an improvement in the performance of fish. Finally, the best final body weight, weight gain, specific growth rate, protein efficiency ratio, and protein productive value were recorded by a fish-fed mixed plant protein diet (FSM + CG + Meth). Also, Hematocrit and red blood cells were not significantly affected including the FSM.