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

日本近50%的牛奶生产在北海道地区进行，那里的奶牛主要在牧场上饲养，5月至10月期间超过60%的奶牛在牧场上饲养。然而，很少有人知道这种牛奶的质量与牧场饲养有关。本研究的目的是阐明放牧对牛奶的影响，特别是对牛奶中的糖成分的影响。试验期放牧组与非放牧组的己糖浓度（中性糖组分）无显著差异，而各放牧奶牛乳中总唾液酸浓度（酸性糖组分）较试验期第0 d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缀合物的浓度。在不久的将来，需要对放牧管理导致牛奶中总唾液酸浓度升高的原因和影响进行研究。

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.