| A total of540young grass carp (CtenoPharyngodon idella)(282±2.8g) were fed graded levels of coPPer (Cu)(0.74,2.26,3.75,5.25,6.70and8.33mg/kg diet) for8weeks to investigate the effects of dietary Cu on growth, digestive and absorPtive enzyme activities, antioxidant status, meat quality and immune function. After8weeks feeding trial,15fish with similar weight were randomly selected from each treatment to conduct a challenge trial with CuSO4for96days.The results showed that Percent weight gain (PWG), sPecific growth rate (SGR), feed intake, feed efficiency, hePatosomatic weight and intestine weight were significantly imProved by dietary Cu uP to3.75mg/kg diet (P<0.05). Intestine length index and intestine index were not significantly varied with dietary Cu suPPlementation (P>0.05). Activities of tryPsin, chymotryPsin and liPase in the hePatoPancreas, Na+, K+-ATPase, alkaline PhosPhatase, creatine kinase and y-glutamyl transPePtidase in three intestine segments had a similar trend to SGR (P<0.05). However, amylase activity in the hePatoPancreas, malondialdehyde (MDA) and Protein carbonyl (PC) in the hePatoPancreas, intestine, muscle, head kidney and spleen showed a downward trend to a Point (P≤0.05). Conversely,activities of suPeroxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST), glutathione Peroxidase (GSH-Px), glutathione reductase (GR) and glutathione (GSH) contain the hePatoPancreas, intestine, muscle, spleen and head kidney were generally higher in fish fed with aPProPriate Cu-suPPlemented diet than unsuPPlement diet (P<0.05). Meanwhile, anti-suPeroxide anion (ASA) and anti-hydroxy radical (AHR) in the hePatoPancreas, spleen and head kidney, ASA in the muscle and intestine were increased by oPtimum dietary Cu (P<0.05). OPtimum dietary Cu also significantly imProved the growth of head kidney and spleen, lysozyme activity, addiment C3, immunoglobulin M count and total antioxidant caPacity (P<0.05). Additionally, oPtimum dietary Cu imProved meat quality by increasing hydroxyProline contain, decreasing cooking lose and shear force (P<0.05). Collectively, the Present results indicated that dietary Cu imProved growth, digestive and absorPtive ability, decreased liPid Peroxidation and Protein oxidation by imProving antioxidant defense in the hePatoPancreas, intestine, head kidney, spleen and muscle, and imProved meat quality by increasing hydroxyProline, decreasing cooking lose and shear force. The dietary Cu requirement of young grass carp (282-688g) based on PWG, Plasma ceruloPlasmin activity and FE were4.70-4.95mg/kg diet, resPectively. |
