分娩前後における乳牛蹄壁角質アミノ酸組成の変化

Abstract

The changes in amino acid composition in the horny hoof wall of dairy cows were investigated during the periparturition period, in relation with actual milk yield, dry matter intake (DMI), total digestible nutrients (TDN) and crude protein (CP). The growth of the horny hoof wall was most rapid during the dry period as well as one month prior to and one monthfollowing calving. The horny hoof wall during the dry period was revealed to have lower concentrations of glycine, methionine and histidine and high levels of proline. The concentrations of aspartic acid, threonine, alanine, valline, isoleucine, tyrosine and arginine were closely correlated to milk yield and to DMI, TDN and CP, while those of serine, glycine, phenylalanine and lysine were not to DMI, TDN and CP. From the contents of hystidine, lysine, and arginine the horny hoof wall was considered to be most hardly keratinized during the dry period, while most softened following calving.