An Investigation of Mineral Supplementation of Diet on the Growth and Metabolism of Carp

Abstract

The importance of trace elements in animal metabolism is becoming more and more evident. Trace elements as nutrients play a valuable role in the body, participating in the formation of such highly active biological materials as enzymes, hormones and vitamins. Many investigations have been published on the effect of trace elements on various animals. Recently, there have also been experiments on fish, showing that trace elements influence the growth rate and survival of fish. The difficulty in applying trace elements lies in the dosage; only optimal concentrations have beneficial effects. The present investigation attempted to determine the optimal concentration of cobalt and iodide for development and growth of carp, Cyprinus carpio. The results of the present study demonstrate that cobalt is an essential trace element in the diet for carp. The fish fed a diet containing no cobalt showed an extremely low growth rate and high mortality. A large number of the fish on cobalt-deficient diet were found to suffer from malformation in the tail even when the diet was supplemented with vitamin B12. The dietary cobalt also influenced the haematological characteristics and strengthened resistance to disease in carp. The proximate composition of the fish body and the contents of the cobalt in various organs varied according to the dietary cobalt levels in the diet. Judging from the growth rate of the fish, an adequate amount of cobalt, as cobelt chloride, in the diet of carp was estimated to be 3 mg per kg dry diet. For iodide, the results showed that a diet which was insufficient to maintain adequate thyroid iodide storage in carp did not interfere with the animals' normal growth. However, the results obtained showed that the optimal iodide requirement for carp was 1.2 mg per kg dry diet.