Assessing effects of guar gum viscosity on the growth, intestinal flora, and intestinal health of Micropterus salmoides

A 56-day feeding trial was conducted to assess the effects of different viscous guar gum on the growth, intestinal flora, and intestinal health of Micropterus salmoides. Four practical diets with 42.5 % crude protein and 13.7 % crude lipid were formulated to contain 8 % cellulose and three different viscosities (2500, 5200, and 6000 mPa·s) of guar gum. Dietary guar gum inhibits fish growth and feed utilization, decreases the α-diversity of the intestinal flora, and negatively alters the intestinal flora structure and metabolite composition. High viscous guar gum down-regulated the intestinal tight junction, anti-inflammatory, and anti-apoptotic related gene's expression, decreased digesta butyrate/histamine ratio; and increased the abundance of Plesiomonas shigelloides. These results suggest that dietary guar gum adversely affects intestinal health by disrupting intestinal flora structure and metabolite composition, and that viscosity should be considered when using guar gum as a binder in aquafeeds.