Procambarus clarkii, alias red crayfish or freshwater crayfish, is a world's leading species of freshwater crayfish cultures.

Copper, zinc, iron and manganese hydroxymethionine is an organic type of trace minerals chelated with methionine hydroxy analogue. They are safe, high bioavailable, good palatable and very stable. The properties of low water solubility and high stable chemical structure greatly reduce dissolution of the trace minerals in feed into water and release of ionized metals. As results, it reduces probability of oxidization of feed nutrients such as vitamins, fatty acids and enzymes and loss of the trace minerals in feed and then increase supplemental effectiveness of the trace minerals and improve growth performance, feed efficiency, immunity and survivability of cultured aquatic animals.

In this respect, this experiment was to test the effects of copper, zinc, iron and manganese hydroxymethionine chelates on growth performance and non-specific immunity of Procambarus clarkii. The results would provide a scientific guide in application of the organic trace elements in cultured aquatic animals.

Experimental design

The purchased Procambarus clarkii were raised in a cement pool of 30m3 for 2 weeks. For the experiment, 360 of health animals with an initial weight of 7.50g were selected and allocated into 12 aquariums (80cm × 60cm × 75cm) with 30 animals each. The 12 aquariums were randomly assigned to 2 dietary treatments. The basal diet consisted of fishmeal and soybean, and soybean oil (crude protein = 31.8%, crude fat = 5.32%, lysine = 1.55%, crude fiber = 9.57%, total phosphorus = 0.98%). The treatment diets were prepared by adding normal nutrition level of Cu, Zn, Fe and Mn in form of sulfate salt (T1) and lower nutrition level in form of hydroxymethionine chelate (T2).

Results and Discusions

Growth performances

Table 1 shows that the copper, Zinc, Iron and manganese in form of hydroxymethionine chelate significantly improved weight gain, survivability and feed efficiency of the animals when compared to the animals fed the diet containing copper, zinc, iron and manganese in form of sulfate salt (p<0.05). Weight gain rate, survivability and feed efficiency were improved by 19.79%, 9.65%, and 9.93%, respectively.

Table 1. Effect of copper, zinc, iron and manganese hydroxymethionine chelates on growth performance of Procambarus clarkii

Blood Biochemical Parameters

Table 2 indicates that in comparison with the animals fed the diet containing those trace minerals in form of sulfate salt, Cu, Zn, Fe and Mn hydroxymethionine chelates significantly increased serum ceruloplasmin content and lysozyme activity (P<0.05), but did not impact on total protein concentration and alkaline phosphatase activity of the animals (p>0.05).

Table 2. Effect of copper, zinc, iron and manganese hydroxymethionine chelates on serum biochemicals of Procambarus clarkii

Conclusion

Copper, zinc, iron and manganese hydroxymethionine chelates can significantly improve production performances and feed efficiency of Procambarus clarkia. Significantly enhanced blood ceruloplasmin and lysozyme activity and tendency to increase blood total protein concentration and alkaline phosphatase activity indicate that copper, zinc, iron and manganese hydroxymethionine chelates have potentials to enhance immune response and resistance to diseases in Procambarus clarkia.

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Article made possible through the contribution of XJ BIO-ENGINEERING INTERNATIONAL PTE LTD — Singapore

Effects of Copper, Zinc, Iron and Manganese Hydroxymethionine Chelate on Growth and Immunity of Procambarus clarkii