饲料铜水平对赤眼鳟幼鱼生长性能、体组成和成活率的影响

Effects of dietary copper on survival,growth and body composition of juvenile Squaliobarbus curriculus

以CuSO4·5H2O为铜源,在饲粮中分别添加0、1、2、3、4、6、8、10和12 mg/kg的铜,制得实测铜含量分别为0.29、1.31、2.28、3.43、4.57、6.61、8.77、10.73和12.89 mg/kg的9种饲粮,选取810尾初始体重为(6.22±0.11)g的赤眼鳟(Squaliobarbus curriculus)幼鱼,置于27个300 L的圆柱形水族箱中饲喂56 d,每个水箱放30尾鱼,每个处理设置3个重复。结果表明,①饲粮中未添加铜(0.29 mg/kg饲料铜组)时试验鱼会出现典型的饲粮铜缺乏症状,如生长不良和骨骼畸形。②饲粮中添加4 mg/kg的铜时(4.57 mg/kg饲料铜组),试验鱼的特定生长率、蛋白质效率、肝体比、脏体比和存活率均达到最大,饲料系数达到最小(P<0.05)。③饲粮中添加12 mg/kg的铜时(12.89 mg/kg饲料铜组),试验鱼肝体比、脏体比最低(P<0.05)。④饲粮铜水平对试验鱼肥满度无显著性影响(P>0.05);饲粮铜水平对试验鱼体组成有显著影响(P<0.05);随着饲粮铜水平的升高,试验鱼肝脏和全鱼铜含量均显著升高(P<0.05),肝脏硫代巴比妥酸反应物(TBARS)先降低后升高(P<0.05),在3.43 mg/kg饲料铜组达到最低值。在饲料中添加适量铜可以提高赤眼鳟幼鱼的生长性能和免疫力,对试验鱼增重率和饲料系数进行折线回归分析以及全体铜蓄积量的二次曲线回归分析表明,赤眼鳟幼鱼饲料中铜的适宜量为3.94~4.92 mg/kg。

Treatments consisted of nine semi-purified diets containing graded levels of dietary copper(CuSO4·5H2O was added to a basal diet at 0,1,2,3,4,6,8,10 and 12.0 mg/kg),providing actual dietary values of 0.29,1.31,2.28,3.43,4.57,6.61,8.77,10.73 and 12.89 mg/kg diet,respectively.Each diet was fed to triplicate groups of juvenile Squaliobarbus curriculus with initial body weight of 6.22 g in 300 L cylindrical fiberglass tank.The results showed that the typical dietary Cu deficient signs such as poor growth and malformation of skeleton were observed in fish fed the diets with 0.29 mg/kg diet.Fish fed the diet containing 4.57 mg/kg had the highest specific growth rate(SGR).The lowest hepatosomatic index(HSI)and viscerosomatic index(VSI)were observed in fish fed the diet containing the highest Cu content diet(P<0.05).Condition factor showed no significant differences among the treatments(P>0.05).Proximate composition of fish body was significantly affected by dietary copper level(P<0.05).Cu contents of whole body and hepatic increased with dietary Cu levels(P<0.05).Hepatic thiobarbituric acid reactive substances(TBARS)was found to decrease with increasing dietary concentrations of copper up to 3.43 mg/kg beyond which a reverse trend in this parameter was noted.(Conclu⁃sion)Analysis by the linear regression of weight gain(WG)and feed conversion ratio(FCR)and second-order regression of wholebody Cu retention of the fish indicated that dietary Cu requirement of juvenile Squaliobarbus curriculus was 3.94~4.92 mg/kg diet.