Exploring the Impact of Selected Functional Feed Additives on Growth Performance, Nutrient Utilization, Enzyme Activities and Immune Gene Expression of Striped Murrel (Channa striata) Juveniles.

Abstract

Incorporating selected functional feed additives such as β-glucan, mannan oligosaccharides (MOS), Saccharomyces cerevisiae and Lactobacillus acidophilus into fish diets enhances immunity, gut health, growth and stress tolerance. These natural supplements offer sustainable alternatives to antibiotics, addressing disease outbreaks and poor feed efficiency common in intensive aquaculture. Their use supports eco-friendly practices while improving fish performance and overall farm productivity. The impacts of incorporating varied nutritional supplements into the diet, including β-glucan, MOS, yeast (Saccharomyces cerevisiae) and Lactobacillus acidophilus on growth performance, nutrient utilization, digestive and antioxidant enzyme activities, hemato-biochemical profile and immune gene expression in striped murrel (Channa striata) were examined. Five experimental diets were formulated and prepared as follows: Control, D1 (0.2% β-glucan), D2 (0.3% MOS), D3 (1% Saccharomyces cerevisiae) and D4 (0.02% L. acidophilus). A total of 450 striped murrel (average weight: 15.12 ± 0.26 g per fish) were randomly assigned to 15 experimental cages (1 m × 1 m × 1.5 m; 30 fish per cage) and fed the respective diets three times a day (08.00, 13.00 and 18.00 h) to apparent satiety for 60 days. The findings of the experimental feeding trial elucidated that significantly higher (p < 0.05) growth performance and nutrient utilization were observed in fish fed with the D4 diet, compared to other diets. The dietary supplementation of different probiotic and prebiotic supplemented diets did not significantly affect the whole-body proximate composition and antioxidant enzyme activity in striped murrel. However, fish fed the D4 diet showed significantly higher (p < 0.05) digestive enzyme activity and immune gene (TGF-β1 and NF-κB) expression, compared to other diets. In conclusion, dietary supplementation with 0.02% L. acidophilus (D4 diet) resulted in improved growth performance, digestive enzyme activities and immune gene expression in striped murrel (C. striata).