One reason this may be so frequently found is because cows have been selectively bred this way to increase the protein content of the cow-milk (a quality desired by dairy producers). 9
其原因之一可能因为牛是通过选择性繁殖的方式来提高牛奶的蛋白质含量（乳品生产者所期望的品质）的。
Laoshan dairy goat is a new developed goat bred in China.
崂山奶山羊是我国培育的一个山羊品种。
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