Effect of prolonged administration of B-glucan on the innate immunity of tilapia, Oreochromis niloticus

• Grant number: 19/23214-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: December 01, 2019
• End date: November 30, 2020
• Field of knowledge: Agronomical Sciences - Fishery Resources and Fishery Engineering - Aquaculture
• Principal Investigator: Jaqueline Dalbello Biller Takahashi
• Grantee: Victor Negri Liborio
• Host Institution: Faculdade de Ciências Agrárias e Tecnológicas. Universidade Estadual Paulista (UNESP). Campus de Dracena. Dracena , SP, Brazil
• Associated research grant: 12/22016-3 - Study of the immunostimulating potential of b-glucan and its mode of action aiming at new administration protocols in tilapia, Oreochromis niloticus, AP.JP

Abstract

B-glucan is the most studied compound used in fish feed because it promotes increased cellular and humoral defense components such as phagocytic cells such as macrophages, neutrophils and monocytes, and protective proteins such as lysozyme, complement system and other signaling cytokines, however new administration protocols should be studied in order to clarify possible actions of this immunostimulant. Thus, the aim of the present study will be to evaluate the effects of this long-term immunostimulant on immunological variables (lysozyme activity; complement hemolytic activity; leukocyte respiratory activity "in vitro" method in microplates). A total of 405 tilapias will be distributed in 27 100 L polyethylene boxes, with 15 fish each, and divided into three groups: Group 1. Tilapia will receive 90-day control diets (B-glucan free) and will be sampled after 30, 60 and 90 days of experiment; Group 2. Tilapia will receive diets containing 10g kg-1 of B-glucan for 30 days (and 60 days of control diet) and will be sampled after 30, 60 and 90 days of experiment; Group 3. Tilapia will receive diets containing 10g kg-1 of B-glucan for 60 days (and 30 days of control diet) and will be sampled after 30, 60 and 90 days of experiment. The tilapia will be fed the control diets for 90 days and experimental for 30 and 60 days, respectively, and after 30, 60 and 90 days, 4 fish from each box of all treatments will be sampled, anesthetized in clove oil solution. and will be blood drawn to evaluate immunological variables; and hematological variables. Then the fish will be individually weighed on a semi-analytical digital scale with 0.01 g precision and measured by an ichthyometer for biometric data collection and evaluation of productive performance variables. This experiment will be conducted in a completely randomized design with 9 treatments (control; 30 days of B-glucan feeding; 60 days of B-glucan feeding x 3 sampling times: 30 60 and 90 days of experiment) with 3 replications each.