Resumen de Food restriction in Nile tilapia juveniles (Oreochromis niloticus)

T.A. Lui, Wesley P. da Silva, Juliana A. L. Nervis, Jackeline M. D. Brum, Fabio Bittencourt, Dacley Hertes Neu, Wilson Rogério Boscolo

• Aim of study: To evaluate if dietary restriction influence muscle and intestinal morphology as well as the production performance of juvenile Nile tilapia (Oreochromis niloticus).Area of study: State University of Western Paraná (Universidade Estadual do Oeste do Paraná – Unioeste), Toledo Campus, Brazil.Material and methods: The experimental design was completely randomized with four treatments and five replicates. The treatments were: 7:0 (fed daily; control); 6:1 (fed 6 consecutive days followed by 1 day of fasting); 5:2 (fed 5 consecutive days followed by 2 days of fasting); and 1:1 (fed 1 day followed by 1 day of fasting). A commercial ration with 33.70% crude protein and 4.60% lipid was used, and fish were fed four times daily until apparent satiety for 60 days.Main results: The following parameters were found to have differences among treatments (p<0.05): final weight, weight gain, final length, hepatosomatic index, visceral fat, intestinal quotient, protein efficiency rate, protein retention, ash, and frequency of muscle fiber diameters within the classes of<20 μm and between 20 and 50 μm. The intestinal villi height and hepatic glycogen content did not differ (p>0.05) among treatments. The cost of food and partial net revenue were higher in the 7:0 treatment compared to the experimental treatments.Research highlights: Dietary restriction for Nile tilapia in the juvenile phase negatively influences productive performance, centesimal composition, and muscle growth, which demonstrates that this practice is economically unfeasible for commercial production.