Effect of prebiotic konjac mannanoligosaccharide on growth performances, intestinal microflora, and digestive enzyme activities in yellow catfish, Pelteobagrus fulvidraco

In the present study, konjac mannanoligosaccharide (KMOS) was evaluated as a prebiotic in yellow catfish. The fish were fed with diets containing KMOS in four concentrations: 0 g kg−1 (C), 1.0 g kg−1 (KM1), 2.0 g kg−1 (KM2), and 3.0 g kg−1 (KM3) for 49 days, respectively. Another group fed with diets containing 3.0 g kg−1 yeast cell wall mannanoligosaccharide (MOS) (M3) was set as positive control. The results indicated that fish receiving the diets supplemented with KMOS or MOS showed higher relative gain rate (RGR), specific growth rate (SGR), and lower feed conversion ratio (FCR) with significantly differences (P < 0.05) than those fed with the basal diets. Moreover, fish receiving the diets with 2.0 g kg−1 KMOS inclusion showed higher RGR, SGR, and lower FCR (P < 0.05) than that feeding the diets supplemented with 3.0 g kg−1 MOS. The quantities of Bifidobacterium spp. were significantly increased (P < 0.05). Meanwhile, Escherichia coli and Aeromonas spp. were significantly reduced (P < 0.05) in the fish-feeding diets with 2.0 g kg−1 KMOS supplement. Compared with the control group, the significantly enhancement of protease and amylase activity (P < 0.05) in intestine and pancreas was observed in fish fed with diets containing KMOS or MOS. Collectively, an optimum level of KMOS inclusion in diets could modulate intestinal microflora, induce digestive enzyme activity, and improve the growth performance of yellow catfish significantly.