Effects of Lycium barbarum polysaccharides on growth, digestive enzyme activity and intestinal tissue morphology of Nile tilapia(Oreochromis niloticus)

【Objective】This study clarified the effects of Lycium barbarum polysaccharide(LBP) on the growth,development and digestive function of tilapia. The research results provided theoretical reference for healthy tilapia aquaculture and new ideas for promoting the sustainable and healthy development of tilapia aquaculture industry.【Method】Five different doses(0-2000 mg/kg) of LBP were added to the basic feed of Nile tilapia for a 40-day breeding experiment. After the experiment,the body weight and full length of Nile tilapia were measured to calculated the relative weight gain rate(WG),relative growth rate(LG),specific growth rate(SGR) and feed coefficient(FCR). ELISA kits were used to detect the activities of amylase,protease and lipase. The foregut,midgut and hindgut tissue sections of the experimental fish were prepared to observe the changes of intestinal tissue morphology.【Result】Adding different doses of LBP to the food could promote the growth and development of Nile tilapia. The group supplemented with 1500 mg/kg had the best promo-ting effect,and the final full length,final body weight,WG,LG and SGR reached the highest,which were 13.45 cm,48.74 g,6.96%,0.94% and 5.19%/d,respectively. FCR was the smallest,only 1.88. The activities of protease and amylase in midgut tissue significantly increased in 1500 mg/kg treatment group(P<0.05,the same below). The activities of protease and amylase in stomach tissue activities of lipase in liver tissue were also the highest in 1500 mg/kg treatment group. The However, there was no significant difference compared with the control group(0 mg/kg) (P>0.05). The villus length of the foregut tissue was the shortest(0.351 mm) and the villus length of the hindgut tissue was the longest(0.320 mm) in the 1500 mg/kg treatment group,representing significante difference compared with the control group(0 mg/kg). The muscle layer thickness in the foregut and midgut tissues were the thickest in the 500 mg/kg treatment group,at 0.089 and 0.087 mm,respectively. The muscle layer thickness of hindgut tissue was the thinnest(0.065 mm) in the 1000 mg/kg treatment group,and was the thickest(0.099 mm) in the 2000 mg/kg treatment group.【Conclusion】LBP can promote the growth and development of Nile tilapia by increasing the activity of digestive enzymes and improving the morphology of intestinal tissue. Adding 1500 mg/kg LBP to the feed has the best effect.