Effects of dietary copper sources and levels on performance, copper status, plasma antioxidant activities and relative copper bioavailability in Carassius auratus gibelio

The experiment was conducted to compare the effects of dietary tribasic copper chloride (TBCC), copper amino acid complex (Cu–AA) and copper sulfate on performance, copper status and plasma antioxidant activities in crucian carp, Carassius auratus gibelio , fed a fish meal based diet. Two hundred and eighty crucian carps (18.10 ± 0.04 g average body weight) were randomly assigned to 10 treatments. Treatments consisted of 0, 3, 6 or 9 mg supplemental Cu/kg from TBCC, Cu–AA or copper sulfate. Growth performance, copper status and plasma antioxidant activities were analyzed after a 55-day feeding period. Fish fed diets supplemented with copper at levels of 3–6 mg/kg had obviously higher WG and SGR ( p 0.05) and relatively lower FCR ( p > 0.05) than fish fed the basal diet. Whole-body copper concentrations were significantly higher in fish fed diets supplemented with 3–9 mg Cu/kg (independent on copper sources) than fish fed the basal diet ( p 0.05). There was a trend that fish fed diets with Cu–AA had higher liver copper than those fed diets with equal levels of copper from copper sulfate or TBCC ( p > 0.05). Fish consuming diets supplemented with 6 or 9 mg Cu/kg from Cu–AA, or 9 mg Cu/kg from TBCC had significantly higher ceruloplasmin activities than those fed diets with 3 mg Cu/kg from either TBCC or copper sulfate ( p 0.05). GSH-Px activities were obviously higher in fish fed diets supplemented with 6 or 9 mg Cu/kg from copper sulfate than fish fed the basal diet ( p 0.05). Using linear regression and a slope ratio technique, relative bioavailability values (RBVs) of TBCC were 1.18, 1.31 and 1.73, based on plasma ceruloplasmin, plasma copper and liver copper, respectively, and RBV of Cu–AA were 1.04, 1.00 and 1.42, compared with copper sulfate (1.00). This study showed that TBCC is more bioavailable to crucian carp than copper sulfate and could be used as a new copper source.