Influence of a mixture of oligosaccharides and β-glucan on growth performance, feed efficacy, body composition, biochemical indices, combating Streptococcus iniae infection, and gene expression of Nile tilapia (Oreochromis niloticus)

A 60-feeding day was performed to explore the potential influence of dietary intervention with a mixture of oligosaccharides and β-glucan (OLG) on growth, feed utilization, body composition, biochemical parameters, growth-related genes, and resistance to Streptococcus iniae infection of Nile tilapia ( Oreochromis niloticus ). Fish ( n = 360, average weight 24 ± 0.2 g) were allotted into four experimental groups. Fish were received basal diets and inclusion of a mixture of oligosaccharides and β-glucan (1:1) at various levels 0 (OLG0), 1 (OLG1), 1.5 (OLG1.5), and 2 (OLG2) g/kg feed for 60 days. Fish were erratically scattered into tanks at a density of 30 fish/tank and the experiment was conducted in triplicates. All OLG groups had better final body weight, feed conversation ratio (FCR), and body weight gain and percentages ( p 0.05). Fish fed with 1.5 or 2 g of OLG exhibited higher SGR, survival rates, and ADG than the OLG1 and OLG0 groups. All OLG-treated groups significantly improved the fish body composition in dose-dependent manner ( p