Apparent digestibility of various feedstuffs for bluntnose black bream Megalobrama amblycephala Yih

The apparent digestibility of 66 different feedstuffs by the bluntnose black bream Megalobrama amblycephala Yih was determined in digestibility trials in a recirculation aquaculture system. The ingredients consisted of 26 distinct energy feedstuffs, 18 nonanimal protein feedstuffs and 22 animal protein feedstuffs. In each of three trials, a reference diet was mixed with various test ingredients in a 70 : 30 ratio; reference and test diets were fed to the fish, and faecal samples were collected using a hand-held screen system. Energy availability for the 26 energy feedstuffs varied between -23.0% (silkworm manure) and 89.5% (millet grain), protein digestibility for the 18 nonanimal protein ingredients varied from 58.0% (pea protein meal) to 98.1% (soybean meal), and protein digestibility for the 22 animal protein feedstuffs varied between -5.7% (feather meal) and 99.1% (fermented dried blood meal). The average protein digestibility of 85.9% for the nonanimal protein feedstuffs was significantly higher than that for the animal feedstuffs (P < 0.05), partly validating the assumption that herbivorous bluntnose black bream would digest proteinic nutrients in nonanimal feedstuffs better than in animal ingredients under intensive aquaculture. Finally, the energy availability of nonanimal protein feedstuffs was significantly lower than that of animal feedstuffs (P < 0.05).