PROBLEM TO BE SOLVED: To provide a modified colostrum protein and a method for using the same.SOLUTION: According to the present invention, there is provided a modified colostrum protein, which is a wild-type colostrum protein having an amino acid sequence in which isoleucine at position 33 is substituted with alanine, glutamic acid at position 101 is substituted with cysteine, and arginine at position 175 is substituted with cysteine. There is also provided a method for producing a feed, the method inducing animal immunity with an animal feed composition comprising the modified colostrum protein. There is further provided a method for producing a pharmaceutical composition comprising the modified colostrum protein. There is further provided an animal feed composition in which the ratio of the modified colostrum protein contained in the animal feed composition is 0.01 to 0.02 wt%.SELECTED DRAWING: Figure 1【課題】修飾初乳蛋白質、及びその使用方法の提供。【解決手段】野生型初乳蛋白質のアミノ酸配列における３３番目のイソロイシンがアラニンに置換され、第１０１番目のグルタミン酸がシステインに置換され、及び第１７５番目のアルギニンがシステインに置換されたアミノ酸配列を有する修飾初乳蛋白質。該修飾初乳蛋白質を含む動物飼料組成物による動物の免疫を誘発する飼料を製造する方法、及び修飾初乳蛋白質が含まれる医薬組成物を製造する方法。前記修飾初乳蛋白質が前記動物飼料組成物に含まれる比率が、０．０１～０．０２ｗｔ％である動物飼料組成物。【選択図】図１
