Characterization of the structures and roles of glycoconjugates in pasture-based milk for manufacturing of high quality cheese

日本近50%的牛奶生产是在北海道地区进行的，那里的奶牛主要在牧场饲养，从5月到10月超过60%。然而，在牧场饲养方面，人们对这种牛奶的质量知之甚少。本研究旨在阐明放牧对乳糖组成的影响，尤其是放牧对乳糖组成的影响。放牧与非放牧奶牛乳中己糖浓度(中性糖组分)在试验期内差异不显著，而每头放牧奶牛乳汁中总唾液酸(酸性糖组分)浓度较试验期第0d显著升高。这些结果表明，放牧管理可能增加了牛奶中唾液糖偶联物的浓度。放牧管理使牛乳中总唾液酸浓度升高的原因和效果有待进一步研究。

Almost 50% of milk productions in Japan have been performed in Hokkaido region, where dairy cows are mainly fed in pasture with more than 60% from May to October. However, little is known regarding the quality of this milk with respect of pasture-based feeding. The purpose of the present study was to clarify the influence, especially for sugar compositions in milk by grazing. There was no difference in hexose concentration (neutral sugar fractions) between grazing and non grazing groups during the experimental period, while total sialic acid concentration (acidic sugar fractions) in the milk of each grazing cow significantly increased compared with that at 0 d of the experimental period. These results indicate that grazing management could have increased the concentration of sialylglycoconjugates in milk. It needs to study the reason and effect of this increasing of total sialic acid concentration in milk by grazing management, near future.