乳牛

Its safety and efficacy were tested and used to immunize the lactational and gestational bovines.

分别免泌期和妊娠牛，收集免。

You cannot sell the cow and sup the milk.

能既想卖牛,又想喝牛奶。

Only because yak is living in remote area and oxherd, with low knowledge,  has less communication with outside world , the yak is less heard and popular as sheep and milk cow.

只因牦牛栖息在偏远地区，养畜牦牛的牧民又甚少与界接触，知识水平都普遍低下，致牦牛的经济价值及羊和牛般广为人知。