| Tribasic copper chloride (TBCC) is a more concentrated form of copper than copper sulfate (58%vs25%Cu). Since it has low hygroscopicity and is insoluble in neutral water, it should be a less reactive and less destructive form of copper when combined with vitamins in diets. Studies with weanling pigs, chicks and steer indicated that tribasic copper chloride was as effective as or more bioavailable than copper sulfate in improving growth. This paper was conducted to study the effects of dietary tribasic copper chloride on growth performance, copper status, antioxidant activities and intestinal microflora in Carassius auratus gibelio and Megalobrama amblycephala, and to evaluate relative bioavailabilities of different copper sources in freshwater fish.1Effects of dietary tri-basic copper chloride on growth, digestibility, intestinal bacteria and blood chemistry in Carassius auratus gibelioThis experiment was conducted to study the effects of dietary tribasic copper chloride (TBCC) on growth, digestibility, intestinal bacteria, blood chemistry and copper status of Carassius auratus gibelio. Two hundred and forty fish (59g of initial average body weight) were randomly distributed into12tanks,20fish per tank. Triplicate groups of fish were fed a basal diet (control) containing5mg Cu kg-1diet from copper sulfate, or this diet supplemented with50,100or150mg TBCC kg-1diet. Growth, digestibility, intestinal bacteria, blood index and tissue copper were measured. The results showed that fish fed dietary TBCC of50,100and150mg kg-1increased weight gain ratio by22.66%(P＜0.05),11.90%(P>0.05) and15.03%(P>0.05), respectively, compared to fish fed the control diets. Fish fed dietary TBCC of100mg kg-1had highest apparent digestibility for dry matter, protein and copper and had the lowest feed conversion ratio among all the treatments(P＜0.05). Intestinal Escherichia coli contents were significantly reduced by 19.63%and15.93%in fish fed dietary TBCC of100and150mg kg-1; Bacillus contents were significantly increased by12.54%,9.70%and8.16%(P＜0.05) in fish fed dietary TBCC of50,100and150mg kg-1, respectively, compared fish fed the control diets. Dietary TBCC significantly increased plasma ceruloplasmin activities (P<0.05); fish fed fed dietary TBCC of50mg kg-1had higher GSH-Px activity, compared to those fed the basal diet (P<0.05). Liver copper concentrations in fish fed dietary TBCC of100and150mg kg-1were significantly higher than those in fish fed the control diets (P<0.05). This study demonstrated that dietary TBCC could influence growth, digestibility and blood chemistry in Carassius auratus gibelio; when dietary TBCC at levels of100-150mg kg-1could significantly affect structure of intestinal microflora, which suggested that dietary TBCC is effective for Carassius auratus gibelio.2Gastrointestinal processing and assimilation of tribasic copper chloride in vivo of Carassius auratus gibelioGastrointestinal processing and assimilation of tribasic copper chloride (TBCC) in vivo was investigated by sequential chyme analysis over a96h period following ingestion of a practical diet with100mg TBCC kg-1diet by Carassius aurutus gibelio (150g of initial average body weight). The results showed that most TBCC dissolved in the intestine at8-12h; the mucus may bind some copper at8h. Copper absorption by intestine happened since24h and copper transportation to other tissues in fish happened since72h.3Effects of tribasic copper chloride, copper amino acid complex and copper sulfate on performance, copper status in Carassius auratus gibelioThe 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 in Carassius auratus gibelio, fed a fish meal based diet. Two hundred and eighty fish (18g of initial average body weight) were randomly assigned to10treatments. Treatments consisted of0,3,6or9mg supplemental Cu kg-1from TBCC, Cu-AA or copper sulfate. Growth performance and copper status were analyzed after a55-day feeding period. Fish fed diets supplemented with copper at levels of3-6mg kg-1had obviously higher WG and SGR (P＜0.05) and relatively lower FCR (P>0.05) than fish fed the basal diet. When dietary copper level was at3mg kg-1, fish fed diets with TBCC got relatively higher SGR than those fed diets with Cu-AA and copper sulfate (P>0.05). Whole-body copper concentrations were significantly higher in fish fed diets supplemented with3-9mg Cu kg’1(independent on copper sources) than fish fed the basal diet (PO.05). Tissue copper concentrations were highest in kidney, intermediate in intestine, and lowest in gill and muscle. Muscle copper concentrations were not related to dietary copper levels (P>0.05). Intestinal copper concentrations were not affected by dietary copper sources (P>0.05), but increased with elevated dietary copper (p<0.05). There was a trend for gill copper concentrations to be reduced by elevating dietary copper (P>0.05). This study showed that dietary optimal level of copper from TBCC was suggested to be3-6mg Cu kg1.4Relative copper bioavailabilities of tribasic copper chloride, copper amino acid complex and copper sulfate in Carassius auratus gibelioThe experiment was conducted to compare the effects of dietary tribasic copper chloride (TBCC), copper amino acid complex (Cu-AA) and copper sulfate on plasma antioxidant activities, copper level in liver and plasma in Carassius auratus gibelio, fed a fish meal based diet. Two hundred and eighty fish (18g of initial average body weight) were randomly assigned to10treatments. Treatments consisted of0,3,6or9mg supplemental Cu kg-1from TBCC, Cu-AA or copper sulfate. Plasma antioxidant activities, copper level in liver and plasma were analyzed after a55-day feeding period. Fish consuming diets supplemented with6or9mg Cu kg-1from Cu-AA, or9mg Cu kg-1from TBCC had significantly higher ceruloplasmin activities than those fed diets with3mg Cu kg-1from either TBCC or copper sulfate (P＜0.05). GSH-Px activities were obviously higher in fish fed diets supplemented with6or9mg Cu kg-1from copper sulfate 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). Using linear regression and a slope ratio technique, relative bioavailability values (RBVs) of TBCC were1.18,1.31and1.73, based on plasma ceruloplasmin, plasma copper and liver copper, respectively, and RBV of Cu-AA were1.04,1.00and1.42, compared with copper sulfate (1.00). This study showed that TBCC is more bioavailable to Carassius auratus gibelio than copper sulfate and could be used as a new copper source. 5Effects of tribasic copper chloride on growth, copper status of Megalobrama amblycephala fed practical dietsA study was conducted to investigate the effects of dietary tribasic copper chloride on growth, copper status in Megalobrama amblycephala. Eight practical diets containing different levels of copper (0,3,6,9,25,50,100and150mg Cu kg-1) from tribasic copper chloride were fed to Megalobrama amblycephala (31g of initial average body weight) in quadruplicate groups in outdoor cages. Growth and copper status were analyzed after a56-day feeding period. Weight gain and specific growth rates in fish fed diets supplemented with3-6mg Cu kg-1were significantly higher than those in fish fed the control diets (which supplemented with0mg Cu kg-1)(P＜0.05). Fish fed diets supplemented with9mg Cu kg-1had significantly lower feed conversion ratio than fish fed the control diets (P＜0.05). Copper concentrations in liver, kidney and intestine were significantly higher in fish fed diets with50-150mg Cu kg-1than those in fish fed the control diets (P＜0.05). The study showed that diets supplemented with3-6mg Cu kg-1could meet the copper requirements for Megalobrama amblycephala fed practical diets; diets supplemented with9mg Cu kg-1could increase feed efficiency; diets supplemented with100mg Cu kg-1increase copper accumulation in tissues.6Effects of tribasic copper chloride on antioxidant activities, immune responses and intestinal microflora of Megalobrama amblycephala fed practical dietsA study was conducted to investigate the effects of dietary tribasic copper chloride on antioxidant activities, immune responses and intestinal microflora in Megalobrama amblycephala. Eight practical diets containing different levels of copper (0,3,6,9,25,50,100and150mg Cu kg-1) from tribasic copper chloride were fed to Megalobrama amblycephala (31g of initial average body weight) in quadruplicate groups in outdoor cages. Antioxidant activities, immune responses and intestinal microflora were analyzed after a56-day feeding period. Dietary copper at levels ranging from9mg kg-1to100mg kg-1significantly enhanced T-AOC activities (P＜0.05). In addition, diets supplemented with100-150mg Cu kg-1significantly increased activities of AKP and ACP (P＜0.05). Intestinal bacterial community structures in fish fed diets supplemented with6-150mg Cu kg-1were different from those in fish fed diets supplemented with0-3mg Cu kg-1. The study showed that diets supplemented with9or25mg Cu kg-1could significantly enhanced T-AOC activities; diets supplemented with100mg Cu kg’1could increase activities of T-AOC, AKP and ACP; diets supplemented with9,25or100mg Cu kg-1had similar intestinal microflora structure, which different from those in fish fed the control diets. |
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