Microbial phytase and myo-inositol supplementation: potential effects on growth performance, immunological status and antioxidant system of Nile Tilapia subjected to a bacterial challenge

• Grant number: 23/07863-6
• Support Opportunities: Regular Research Grants
• Start date: November 01, 2023
• End date: December 31, 2024
• Field of knowledge: Agronomical Sciences - Fishery Resources and Fishery Engineering - Aquaculture
• Principal Investigator: Margarida Maria Barros
• Grantee: Margarida Maria Barros
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil
• City of the host institution: Botucatu
• Associated researchers: Samir Moura Kadri
• Associated scholarship(s): 23/16388-0 - Microbial phytase and myo-inositol supplementation: effects on growth performance, immune system, gene expression and antioxidant capacity of Nile tilapia subjected to bacterial infection, BP.TT

Abstract

This study aims to assess the effects of myo-inositol (MI) and phytase (UF) supplementation on growth performance, antioxidant status and health of Nile tilapia subjected to Aeromonas hydrophila infection. The study will be divided in two phases: growth performance and immunological challenge. In the first phase, 675 juveniles (~15 g) will be randomly distributed in 45 250-L aquaria. Fish will be fed the respective diets for 90 days. After that period, growth performance, body chemical composition, gene expression of Nrf-2 and antioxidant system enzymes will be assessed. Subsequently, five fish per treatment will be sampled to evaluate: hematological profile, antioxidant enzyme activity (superoxide dismutase, catalase and glutathione peroxidase) and innate immune response (neutrophil metabolism burst, lysozyme, and complement system activity). The data obtained will be used as a parameter for comparison before stress. The second phase will be a 15-day bacterial challenge conducted with a group of 180 juveniles from the first phase. The same immunological, genic, and antioxidant parameters will be re-evaluated after the challenge to generate the after-stress data. The study will be carried out in a completely randomized design with nine treatments and five replicates as follows: control (no supplementation), four phytase levels (500, 1500 2500 and 3500 UF kg-1), and four MI levels (300, 600, 900, 1200 mg kg-1). Fish will be fed four times a day until apparent satiation. The data will be subjected to one-way variance analysis (ANOVA). Posteriorly, a Tukey's test (P < 0.05) will be used to compare the supplementation effects on the evaluated parameters. Polynomial regression analysis will be used to determine optimum dietary levels of MI and UF for the evaluated parameters. Variables that do not follow normal distribution will be evaluated by the Kruskal-Wallis test and complemented by the Mann-Whitney's comparison test. Differences will be considered statistically significant at P < 0.05. (AU)