Effects of stocking density on growth, digestive enzyme activities and biochemical indices of juvenile Procambarus clarkii

Abstract

Stocking density is a crucial factor involved in aquatic productivity.This paper evaluates the effects of stocking density on growth,digestive enzyme activities and biochemical indices of juvenile Procambarus clarkii,whose initial average body weight was(0.015±0.004) g.A 30-day rearing experiment was conducted at the stocking densities of 50,100,300,600,and 900 individuals/ m 2.Results showed that the final body weight of juvenile P.clarkii decreased with the increasing stocking density.The activities of pepsin,tryptase,and amlase presented the reduced trend with the increasing stocking density,while cellulase,lipase,and the content of moisture were indistinctly changed(P 0.05).The content of crude protein increased from 54.02% to 60.75%(P 0.05),and also,muscle concentrations of triglyceride,total protein,urea nitrogen,and cholesterol increased(P 0.05) with the increasing stocking density,while the content of crude fat decreased from 26.19% to 19.19%(P 0.01),and concentration of glucose in muscle in the same manner.Increasing trends of hepatopancreas concentrations of glucose,triglyceride,total protein,and urea nitrogen with the increasing stocking density were observed.These data indicate that high stocking density exerts a negative impact on the growth and digestive enzymes of juvenile Procambarus clarkii,and could alter the contents of protein,fat,glucose,and urea nitrogen.