In vitro and in vivo effects of isolated or combined immunonutrients on nutrition and health of Nile tilapia (Oreochromis niloticus) subjected to bacterial challenges

• Grant number: 17/06122-1
• Support Opportunities: Scholarships in Brazil - Post-Doctorate
• Effective date (Start): July 01, 2017
• Effective date (End): February 29, 2020
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Animal Nutrition and Feeding
• Principal Investigator: José Eurico Possebon Cyrino
• Grantee: Pedro Luiz Pucci Figueiredo de Carvalho
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

Antibiotics and chemotherapeutics have been used in the treatment of bacterial infections associated with the intensification of aquaculture practices. However, these measures are not appropriate from the environmental and biosafety points of view, which stimulates the search for sustainable alternatives. In recent years, the use of nutritional strategies and immunonutrition have emerged as promising tools for disease prevention and control. Based on the foregoing, two studies will be developed: in Study I, leukocytes from head-kidney, spleen and peripheral blood of healthy Nile tilapia will be isolated and cultured in vitro. Then, different culture media will be prepared containing, in isolated or combined form: ²-glucan, functional amino acids (arginine and glutamine), and micronutrients related to the antioxidant system (vitamins C, vitamin E, zinc and selenium). The non-specific immune response will be evaluated through the following parameters: phagocytic activity, respiratory burst, bactericidal activity and nitric oxide production. The best results found in this first step will then be applied in Study II, which aims to determine the immunomodulatory capacity of these nutrients in vivo through the hematological and immunological responses of Nile tilapia juveniles fed supplemented diets for different periods and subjected to bacterial challenge (Streptococcus agalactiae and Francisella sp). The data obtained will be analysed by one-way analysis of variance (ANOVA) followed by Tukey's test. 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)