Mineral nutrition in fish. XX. Availability to carp of manganese in whitefish meal and of various manganese compounds.

Abstract

Feeding experiments were conducted to examine availability to carp of Mn contained in white fish meal and that of various Mn compounds (MnSO4, MnCO3, MnO2, MnCl2) and to determine a minimum supplementary Mn levels to white fish meal based diet for normal growth of carp. The lowest growth and the highest rate of occurrence of dwarfism were observed in the fish receiving a diet without supplementary Mn (No-Mn diet) and were effectively improved by the addition of Mn at a level more than 10μg/g wlth MnSO4 or MnCl2, but not by MnO2 and MnCO3. The results of these experiments have demonstrated that supplementation of Mn at more than 10μg/g to white fish meal diets is necessary to obtain normal growth of carp without appearance of dwarfism and that MnSO4 or MnCl2 is most suitable as a Mn source. No Mn diets used in these experiments contained 2-3μg of Mn/g diet derived mostly from white fish meal, and the addition of 10μg of Mn to the diets, namely 12-13μg of Mn in total is equivalent to the Mn re-quirement of carp which resulted in satisfactory performance in terms of growth, feed efficiency and nonappearance of dwarfism. This result indicates a high availability to carp of Mn in white fish meal. The availability of MnO2 and MnCO3 to carp was found to be low in carp.