| 摘要 |
PROBLEM TO BE SOLVED: To obtain a pisciculture feed containing an oligopeptide produced by hydrolyzing wheat protein and effective for decreasing the damage in fishery by improving the resistance of cultured fish to streptococcicosis and lowering the mortality of fish caused by the deterioration of the culture field environment e.g. by the generation of water mass having low oxygen content. SOLUTION: This feed contains an oligopeptide produced by hydrolyzing wheat protein or corn protein (preferably an oligopeptide having a peptide chain length of 2-6). The hydrolysis can be carried out e.g. by using an alkaline protease originated from alkalophilic bacteria preferably at pH9-11 and 50-60 deg.C for 5-30hr using 0.1-1g (20,000-200,000 unit) of the alkaline protease based on 100g of the protein substrate. The oligopeptide is preferably added to a feed at a ratio of 0.01-1% and administered at a daily rate of 25-500mg in terms of the peptide based on 1kg of the fish. |
