Dietary supplementation with mannan oligosaccharide influences growth, digestive enzymes, gut morphology, and microbiota in juvenile striped catfish, Pangasianodon hypophthalmus

This study was conducted to evaluate the effects of mannan oligosaccharide (MOS) dietary supplementation on growth, digestive enzyme activities, gut morphology, and microbiota in striped catfish (Pangasianodon hypophthalmus). Triplicate groups of juvenile striped catfish (initial weight 20.41 +/- 1.64 g) were fed twice per day at 2.5 % of body weight for 12 weeks, with 0 (control), 0.2, 0.4, 0.6, or 0.8 % MOS diets. Compared to control (0.74 +/- 0.03) and fish fed low MOS concentration, those fed 0.6 % (1.01 +/- 0.02) or 0.8 % (1.03 +/- 0.03) MOS had significantly higher (P < 0.05) specific growth rates. Feed conversion ratio and protein efficiency ratio, respectively, significantly improved (P < 0.05) in fish fed 0.6 % (1.62 +/- 0.23; 1.71 +/- 0.23) or 0.8 % (1.42 +/- 0.06; 1.92 +/- 0.08) MOS. Further, compared to control and fish fed 0.2 % MOS, those fed 0.6 % MOS had significantly higher (P < 0.05) apparent protein and dry matter digestibilities. Amylase, protease, and lipase activities, respectively, were significantly higher (P < 0.05) in fish fed 0.6 % MOS (5.10 +/- 0.97; 0.47 +/- 0.08; and 5.59 +/- 1.82) than in control (2.60 +/- 0.53; 0.32 +/- 0.05; and 3.78 +/- 0.72). Histological analysis of the anterior and posterior gut showed significantly higher (P < 0.05) villus length in 0.6 and 0.8 % MOS fed fish than in the control and other treatments. The guts of fish fed different MOS concentrations showed similar total lactic acid bacteria counts, which were significantly higher (P < 0.05) than those in the control. Thus, 0.6 % MOS-supplemented diet improved growth, feed utilization, digestive enzyme activities, gut morphology, and microbiota in juvenile striped catfish.