Digestibility of dry matter and nutrients from three ingredients by the carps, Labeo fimbriatus (Bloch, 1795) and Cyprinus carpio Linnaeus, 1758 with a note on digestive enzyme activity

Abstract

This study was conducted in indoor, aerated plastic tubs to estimate the digestibility of dry matter and nutrients by the carps, Labeo fimbriatus (Bloch, 1795) and Cyprinus carpio Linnaeus, 1758, from three feed ingredients viz., azolla, soybean meal and silkworm pupa incorporated at levels ranging from 0-40% in a diet comprising equal amounts of rice bran and groundnut oil cake using crude fibre as the marker. Activity of the major digestive enzymes was also estimated in the gut of fish at the end of the experimental trial. Utilisation of azolla protein was comparable with that of control diet up to 20% incorporation in both L. fimbriatus and common carp. Major nutrients from soybean were better utilised up to 40% incorporation by the two species. Protein digestibility from silkworm pupae increased at 20% incorporation and decreased at 40% in L. fimbriatus, while fat and nitrogen-free extract digestibility was higher at 20-40% incorporation. In common carp, higher digestibility of protein and fat was recorded at 10-30% inclusion levels of silkworm pupa.