PROBLEM TO BE SOLVED: To provide a livestock meat quality improving agent and livestock meat quality improving method, which can control hardness of meat or meat grain feeling in a short period, in a simple manner at a low cost and to provide a livestock.SOLUTION: There is provided the livestock meat quality improving agent containing acetylhydroxyproline in which shear stress (SFV), cutting stress (SAC) and the mass ratio between insoluble collagen and soluble collagen (insoluble collagen/soluble collagen) are increased.COPYRIGHT: (C)2013,JPO&INPIT【課題】短期間で簡便かつ安価に、食肉の硬さや肉粒感を制御することができる家畜肉質改善剤、家畜肉質改善方法及び家畜の提供。【解決手段】本発明の家畜肉質改善剤は、アセチルヒドロキシプロリンを含有し、家畜の筋肉における剪断応力(SFV)、切断応力(SAC)、及び不溶性コラーゲンと可溶性コラーゲンとの質量比(不溶性コラーゲン/可溶性コラーゲン)を増加させる。【選択図】なし