Effect of β-glucan in water on growth performance, blood status and intestinal microbiota in tilapia under hypoxia

• Main Authors: Felipe Pinheiro de Souza, Ed Christian Suzuki de Lima, Victor César Freitas Pandolfi, Natalia Gonçalves Leite, Pâmela Juliana Furlan‐Murari, Cindy Namie Seino Leal, Raffaella Meneguetti Mainardi, Suelen Aparecida Suphoronski, Leonardo Mantovani Favero, João Fernando Albers Koch, Ulisses de Pádua Pereira, Nelson Mauricio Lopera-Barrero
• Format: Article
• Language: English
• Published: Elsevier 2020-07-01
• Series: Aquaculture Reports
• Subjects: Fish; Metagenomics; Oreochromis niloticus; Prebiotics; Stress
• Online Access: http://www.sciencedirect.com/science/article/pii/S2352513419304752

In the present study, the effects of β-glucan administration in water on growth performance and blood status (hematological indexes, immunological and biochemical parameters) were evaluated in Nile tilapia fingerlings (Oreochromis niloticus) under hypoxia-induced stress. In parallel, effect of this prebiotic (beta-glucan) was evaluated on gut microbiota diversity (16S rRNA gene) under normal oxygenation condition. Three treatments were implemented according to beta-glucan water supplementation: 0 (control), 0.1 and 0.3 mg L−1. Blood was collected before hypoxic challenge (BHC) and 9 h after hypoxic challenge (AHC). No significant differences were observed according to growh performance parameters. A significant increase in erythrocyte number and decrease in mean corpuscular volume (P < 0.05) were identified in control group when were under hypoxia. The plasma glucose level was higher in the 0.3 group than in the 0.1 group BHC; however, for all groups, the glucose level increased markedly AHC, and then receded seven days AHC (7AHC, P < 0.05). Total protein, serum lysozyme, plasma lactate, triglyceride, and cholesterol concentrations did not differ between groups. Comparison of the two β-glucan concentrations indicated that the 0.3 mg L−1 concentration promoted an increase in lymphocyte count. The 0.1 group showed the highest survival rate 7 days after hypoxia. Metagenomic analysis revealed a greater number of operational taxonomic units (OTUs) in the 0.1 and 0.3 groups. The Chao richness value was higher in the 0.1 group than in the control group (P <  0.05), with a greater abundance observed for members of the Vibrionaceae family. It is concluded that the concentration of 0.1 mg L−1 was able to increase tolerance to hypoxia, increasing the survival rate and regulating glucose levels. The concentration of 0.3 mg L−1 modulated hematological responses under stress and increased the lymphocyte count before hypoxic challenge.