Effect of dietary lipid levels on liver free fatty acids,serum biochemical parameters and liver histological structure in mirror common carp at different temperatures

An experiment was conducted to study the effects of dietary lipid levels(5,8,11,and 15%) on liver free fatty acids,serum biochemical and liver histological structure in mirror common carp(Cyprinus specularis) juveniles at different temperature(16,23,and 30 ℃).756 mirror common carp(initial body weight 5.51±0.05 g) were divided into 12 experimental triplicate groups.The results showed that: At 16 ℃,the free fatty acids(FFA) of liver were significantly increased with the increase of dietary lipid level(P0.05),at 30 ℃,the FFA concentration of liver in 15% lipid group was significantly higher than other groups(P0.05);Serum biochemical indicators of change was not same at different temperatures.At 16 ℃,the total protein(TP),globuim(GLB),glutamic-pyruvic transaminase(GPT),glutamic-oxalacetic transaminease(GOT),Triglyceride(TG),total cholesterol(CHOL) and blood glucose(GLU) concentration of serum were significantly increased with the increase of dietary lipid level(P0.05),and ALT,AST,TG and CHOL concentration of serum 15% lipid group was significantly higher than other groups.At 23 ℃,the TP,albumin(ALB),GLB,ALT,AST,total bilirubin(TBIL) and indirect bilirubin(IBIL) concentration of serum were significantly increased with the increase of dietary lipid level(P0.05);At 30 ℃,only ALT and AST concentration of serum increased with the increase of dietary lipid level,and the ALT concentration in 11% and 15% lipid group were significantly higher than in the 5% and 8% groups(P0.05),AST concentration in 15% lipid group was significantly higher than in the 5% and 8% groups(P 0.05);Other indicators were no significantly difference at different lipid levels.Tissue section analysis showed that the mirror carp liver cells have appeared nutritional fatty liver symptoms: irregular,vacuolated,the nucleus offset and swelling with increasing lipid levels at different temperatures.It was easy lead to the formation of nutritional fatty liver and had a obvious impact to liver tissue structure when feed fat levels over 8% at 16 ℃ and over 11% at 23 and 30 ℃.