为了研究幼鱼阶段团头鲂对饲料中铜(Cu)的需要量,以体重50 g左右的团头鲂为试验对象,以五水硫酸铜(CuSO₄·5H₂O)为Cu源配制5种半纯化饲料。5种半纯化饲料中Cu的添加量分别为0、5、10、15、20 mg/kg,实测饲料中Cu含量分别为16.73、21.11、25.24、29.87、34.58 mg/kg。将400尾试验鱼随机分为5组,每组4个重复,每个重复20尾鱼,每组饲喂1种半纯化饲料,在池塘网箱中养殖43 d。结果表明:团头鲂的特定生长率随着饲料中Cu添加量的增加呈先升后降的趋势,Cu添加量为10 mg/kg的组的特定生长率显著高于其他4组(P<0.05),而饲料系数则呈相反的变化趋势。经回归分析,具有最大特定生长率时饲料中Cu添加量为9.94 mg/kg,此时饲料中Cu含量为25.45 mg/kg;具有最小饲料系数时饲料中Cu添加量为10.16 mg/kg,此时饲料中Cu含量为25.65 mg/kg。饲料中添加Cu后团头鲂的脊椎骨长/体长、脊椎骨重/体重均有所增加,其中Cu添加量为20 mg/kg的组脊椎骨长/体长较未添加Cu的组显著增加(P<0.05),Cu添加量为5、15、20 mg/kg的组脊椎骨重/体重较未添加Cu的组显著增加(P<0.05);随着饲料中Cu添加量的增加,内脏指数呈下降趋势,并在Cu添加量为20 mg/kg的组达到最小值,显著低于未添加Cu的组(P<0.05)。随着饲料中Cu添加量的增加,团头鲂的蛋白质沉积率、脂肪沉积率均呈先升后降的趋势,Cu添加量为10 mg/kg的组的脂肪沉积率显著高于其他4组(P<0.05),且该组的蛋白质沉积率显著高于未添加Cu和Cu添加量为20 mg/kg的组(P<0.05)。经回归分析,具有最大蛋白质沉积率时饲料中Cu的添加量为9.62 mg/kg,此时饲料中Cu含量为25.17 mg/kg;具有最大脂肪沉积率时饲料中Cu的添加量为10.15 mg/kg,此时饲料中Cu含量为25.64 mg/kg。综合考虑团头鲂的特定生长率、饲料系数、蛋白质沉积率、脂肪沉积率,得到幼鱼阶段团头鲂对饲料中Cu的需要量为25.17~25.65 mg/kg。

In order to estimate the dietary copper (Cu) requirement of bluntnose black bream (Megalobrama amblycephala) in juvenile fish stage, 5 semi-purified diets with different Cu supplementation of 0, 5, 10, 15 and 20 mg/kg (measured values of Cu contents in 5 diets were 16.73, 21.11, 25.24, 29.87 and 34.58 mg/kg, respectively) were formulated with CuSO₄·5H₂O as the Cu source. A total of 400 bluntnose black bream with an initial body weight about 50 g were used as experimental animal and randomly divided into 5 groups with 4 replicates per group and 20 bluntnose black bream per replicate. Each group of fish was fed one diet for 43 days which cultured with net-cage in pond. The results showed as follows: with the Cu supplementation increasing, the specific growth rate (SGR) of bluntnose black bream was firstly increased and then decreased, and the SGR in the group with the Cu supplementation of 10 mg/kg was significantly higher than that in the other groups (P<0.05), while the feed conversion ratio (FCR) had an opposite trend. Through regression analysis, when ditary Cu supplementation was 9.94 mg/kg, equivalent to ditary Cu content was 25.45 mg/kg, the bluntnose black bream had the maximum of SGR; when ditary Cu supplementation was 10.16 mg/kg, equivalent to ditary Cu content was 25.65 mg/kg, the bluntnose black bream had the minimum of FCR. The spine length/body length and spine weight/body weight of bluntnose black bream were increased after supplemented Cu in diets, and the spine length/body length in the group with the Cu supplementation of 20 mg/kg and the spine weight/body weight in the groups with the Cu supplementation of 5, 15 and 20 mg/kg were significantly higher than those in the group without Cu supplementation (P<0.05). The visceral index showed a down trend with the Cu supplementation increasing, and the minimum of visceral index was found in the group with the Cu supplementation of 20 mg/kg, which significantly lower than that in the group without Cu supplementation (P<0.05). With the Cu supplementation increasing, the protein deposition rate and fat deposition rate of bluntnose black bream were firstly increased and then decreased, and the fat deposition rate in the group with the Cu supplementation of 10 mg/kg was significantly higher than that in the other groups (P<0.05), while the protein deposition rate in this group was significantly higher than that in the groups with the Cu supplementation of 20 mg/kg and without Cu supplementation. Through regression analysis, when ditary Cu supplementation was 9.62 mg/kg, equivalent to ditary Cu content was 25.17 mg/kg, the bluntnose black bream had the maximum of protein deposition rate; when ditary Cu supplementation was 10.15 mg/kg, equivalent to ditary Cu content was 25.64 mg/kg, the bluntnose black bream had the maximum of fat deposition rate. Then, by a comprehensive consideration of the SGR, FCR, protein deposition rate and fat deposition rate of bluntnose black bream, dietary Cu requirement of bluntnose black bream in juvenile fish stage is 25.17 to 25.65 mg/kg.