Effects Of Dietary Chromium Picolinate Levels On Growth Performance, Nutriment Metabolism And Antioxidant Ability Of Heat Stressed Jian Carp (Cyprinus Carpio Var.Jian)

This research was conducted to investigate the effect of dietary chromium picolinate levels on growth performance, nutriment metabolism and antioxidant ability of heat-stressed Jian carp (Cyprinus carpio var. Jian).360 fish (average initial weight, 32.88±0.17 g) were randomly divided into six groups, with 4 replicates respectively. Fish were fed six diets with different chromium picolinate addition (0,300,600,900,1200 and 1500μg/kg) for 60 d (20 d at 26℃, then 20 d at 31℃, last 20 d at 26℃). The experiment were 4 parts.Experiment 1:Effects of chromium picolinate on growth performance, intestinal digestive enzyme activities of heat stressed Jian carpEffects of dietary chromium picolinate levels on growth performance, intestinal digestive enzyme activities of heat stressed Jian carp were investigated. The results showed that weight gain (WG) of fish fed the diet added with 600 and 900μg/kg chromium picolinate increased by 20.12% and 12.57%(P<0.05) respectively than that of control group. WG of fish fed diet with supplemental chromium picolinate of 1500μg/kg decreased by 3.4%(P>0.05). Protein efficiency ratio of fish fed the diet added with 600 and 900μg/kg chromium picolinate were significantly(P<0.05) higher than that of control group, while feed conversion ratio (FCR) decreased significantly (P<0.05). Hepatosomatic index of Jian carp increased with dietary chromium picolinate levels, especially significantly (P<0.05) higher in fish fed the diet supplemented with 900,1200 and 1500μg/kg chromium picolinate. When adding more than 900μg/kg chromium picolinate, viscerosomatic index of Jian carp decreased significantly (P<0.05) compared with control group. Adding 600μg/kg chromium picolinate could increase lipase activity (P<0.05) and protease activity (P>0.05) of intestinal. Chromium picolinate had insignificant effect on amylase activity of intestinal (P>0.05).Experiment 2:Effects of chromium picolinate on nutritions of muscle and liver,and serum biochemical indicators of heat stressed Jian carpEffects of dietary chromium picolinate levels on nutritions of muscle and liver, and serum biochemical indicators of heat stressed Jian carp were investigated. The results showed that there were no significant (P>0.05) differences in lipid, ash, moisture of muscle and lipid of liver for fish fed different diets. Muscle and liver protein content of fish fed diet with 300 and 600μg/kg chromium picolinate was significantly (P<0.05) higher than that of the control group. Adding 600μg/kg chromium picolinate could significantly (P<0.05) increase serum albumin concentration compared with control group, while adding 1500μg/kg chromium picolinate could significantly (P<0.05) decrease serum albumin concentration and total protein concentration. The concentrations of serum total cholesterol and triacyglycerol descreased with chromium picolinate levels.Experiment 3:Effects of chromium picolinate on resist heat stress and antioxdant ability of heat stressed Jian carpEffects of dietary chromium picolinate levels on resist heat stress and antioxdant ability of heat stressed Jian carp were investigated. The results showed that dietary chromium picolinate levels had no significant (P>0.05) effect on serum glucose, insulin and cortisol concentration of heat stressed Jian carp. Adding 600μg/kg chromium picolinate could significantly (P<0.05) increase liver alanine aminotransferase (GPT) activity compared with control group. There were no significant (P>0.05) differences in GPT activity among experiment groups. Liver aspartate aminotransferase (GOT) activity of fish fed diet with 300μg/kg and 600μg/k chromium picolinate were indistinctively (P>0.05), but significantly (P<0.05) higher than other groups. The GOT activity of 1500μg/kg group was lower than all the other groups. Along with the addition of chromium picolinate increasing, liver superoxide dismutase (SOD) and catalase (CAT) activity first increased then decreased, especially 600μg/kg group showed the highest SOD activity (P>0.05). Adding 900μg/kg and 600μg/kg could significantly (P<0.05) increase CAT activity. Chromium picolinate had no significant (P>0.05) effects on liver malondialdehyde (MDA) concentration, but the MDA concentration in 600μg/kg group was the lowest.Experiment 4:Effects of chromium picolinate on chromium distribution of Jian carpEffects of dietary chromium picolinate levels on chromium distribution of heat stressed Jian carp were investigated. The results showed that the distribution of chromium in Jian carp mainly in the kidney, serum, liver, gill, intestine, and muscle distribution is least. The chromium content of liver, kidney, intestine, gill and muscle increased with chromium picolinate levels. Chromium in the liver of control group was indistinctively (P>0.05) compared with 300μg/kg group, while it was significantly (P<0.05) lower than 600,900,1200 and 1500μg/kg groups. There were significant (P<0.05) differences of chromium content in kidney between control group and experiment groups, while the chromium content difference was not significantly(P>0.05) among 600,900 and 1200μg/kg groups. The chromium content of muscle and intestine in experiment groups had no significant(P>0.05) differences compared with control group. The chromium content in gill of control group was lower than 300,600 and 900μg/kg groups, but it was not significantly(P>0.05).It is concluded that the supplementation of 600μg/kg chromium picolinate can increase WG and protein efficiency ration significantly, improve growth, increase muscle and liver protein content, increase SOD and CAT activity and improve the ability to resist heat stress and antioxdant ability of heat stressed Jian carp...