Effects Of Elevated Dietary Copper Levels On Growth Performance And Copper, Iron, Zinc Concentration In Vivo Of Grass Carp, Common Carp And Yellow Catfish

This paper was done to investigate that effects of elevated dietary copper levels on growth performance and copper, iron, zinc concentration in vivo of grass carp, common carp and yellow catfish, to provide test basis for safely adding of dietary copper. The contents are as follows:1. A 56-day experiment was conducted to determine the effects of dietary copper levels on growth performance and copper, iron, zinc concentrations in muscle and hepatopancrears of grass carp Ctenopharyngodon idella (initial weight 25.57±0.47 g·fish^-1). Nine semi-purified diets were formulated to contain 9.38(control), 28.17, 46.21, 80.07, 208.54, 439.50, 679.72, 873.37 and 1365.42 mg Cu·kg^-1 diet (provided as CuSO₄·5H₂O), respectively. The sampling points were settled at the end of 2 w, 4 w, 6 w, 8 w, respectively. The results showed that there were no significant differences of the survival rate, specific growth rate, feed conversion rate, carcass moisture, crude fat and crude ash contents of grass carp fed diets supplemented various concentrations of copper (P>0.05). The contents of crude protein of the grass carp, which were fed diets with the supplement of above 873.37 mg Cu·kg^-1, were significantly lower than that of fish fed control diets (P<0.05). With increasing of dietary copper levels, the copper concentrations in the muscle were not affected (P>0.05), the iron concentrations in the muscle significantly increased (P<0.05), the zinc concentrations in the muscle significantly decreased at the end of 2nd week (P<0.05); the copper concentrations in the hepatopancreas significantly increased; iron concentrations in the hepatopancreas were increased at first and then decreased subsequently at the end of 8th week; zinc concentrations in the hepatopancreas were significantly higher in grass carp fed diets with the supplement of above 439.50 mg Cu·kg^-1 than that of fish fed control diets at the end of 8th week (P<0.05). It showed that the concentrations of copper in muscle and hepatopancreas of grass carp in the experiment were according with related Chinese criterions about aquatic products.2. A 10-week experiment was conducted to determine the effects of dietary copper levels on growth performance and copper, iron, zinc concentrations in muscle and hepatopancrears of common carp Cyprinus Carpio (initial weight 2.24±0.11 g·fish^-1). Nine semi-purified diets were formulated to contain 3.66(control), 27.62, 47.10, 92.62, 227.17, 455.92, 693.05, 817.11 and 1278.48 mg Cu·kg^-1 diet (provided as CuSO₄·5H₂O), respectively. The sampling points were settled at the end of 2 w, 4 w, 6 w, 8 w, 10 w, respectively. The results showed that there were no significant differences of the survival rate, carcass moisture, crude peotein and crude ash contents of common carp fed diets supplemented various concentrations of copper (P>0.05). The contents of crude fat of common carp fed diets with the supplement of 27.62 mg Cu·kg^-1 were highest of all, and significantly higher than that of fish fed control diets (P<0.05). Specific growth rate of the group with 27.62 mg Cu·kg^-1 diet was biggest. Feed conversion rate of the group with 27.62 mg Cu·kg^-1 diet was smallest. With increasing of dietary copper levels, the copper concentrations in the muscle were not affected (P>0.05). Iron concentrations in the muscle were decreased at the end of 10th week. Zinc concentrations in the muscle were decreased at the end of 10th week. Copper concentrations in the hepatopancreas significantly increased. Iron concentrations in the hepatopancreas significantly increased at the end of 2nd week, but were increased at first and then decreased subsequently at the end of 4th, 6th, 8th and 10th week. Zinc concentrations in the hepatopancreas were not affected at the end of 2nd week, but increased at the end of 4th, 6th, 8th and 10th week. Specific growth rate analyzed indicated that the optimal levels for dietary copper in common carp were 27.62 mg·kg^-1. Regression analysis of dietary copper levels and hepatic copper levels at the end of 10th week showed that dietary copper levels of common carp should was <462.68 mg·kg^-1.3. A 12-week experiment was conducted to determine the effects of dietary copper levels on growth performance and copper, iron, zinc concentrations in whole fish of yellow catfish pelteobagrus fulvidraco (initial weight 2.22±0.19 g·fish^-1). Seven semi-purified diets were formulated to contain 3.34(control), 7.01, 25.58, 52.87, 140.17, 432.59 and 1454.12 mg Cu·kg^-1 diet (provided as CuSO₄·5H₂O), respectively. The sampling points were settled at the end of 4 w, 8 w, 12 w, respectively. The results showed that there were no significant differences of the survival rate and moisture, crude protein, crude ash contents of yellow catfish among various concentrations of fish fed diets supplemented copper (P>0.05). The contents of crude fat of the yellow catfish, which were fed diets with the supplement of above 140.17 mg Cu·kg^-1, were significantly lower than that of fish fed control diets (P<0.05).Specific growth rate of the group with 25.58 mg Cu·kg^-1 diet was highest of all. Feed conversion rate of the group with 7.01 mg Cu·kg^-1 diet was smallest. With increasing of dietary copper levels, the copper concentrations in whole body increased on the 4th, 8th, 12th week. Iron concentrations in whole body were increased at first and decreased subsequently on the 12th week. Zinc concentrations in whole body were significantly higher in the group with 1454.12 mg Cu·kg^-1 than the other group. Specific growth rate and feed conversion rate analyzed indicated that the optimal level for dietary copper in common carp were 7.01-25.58 mg·kg^-1, and the dietary copper level of common carp shoulde was <432.59 mg·kg^-1.