What is the ratio of concentrated feed to roughage in dairy cow diet in China?

The ratio of concentrate to roughage is different in different physiological stages of dairy cows. Now people generally don't talk about this when making recipes, mainly the content of acid fiber and neutral fiber. The old habit in China is that the concentrate-to-coarse ratio of high-yield cattle (early lactation and peak lactation) is 50-60: 40-50. The ratio of middle-class cattle is 40: 60; The ratio of low-yield cattle is 30: 70.