The herdsmen and the students have to move from one area to another so that the cows have more grass to eat.

为了让牛有更多的草吃，牧民和学生们不得不从一个地方搬到另一个地方。

youdao

If the grass was good, and the herd moved slowly, the cattle would get heavier and bring more money.

VOA: special.2010.03.18

The pasture is then kept empty until the grass grows to more than Experts say sheep and goats may require special preparations.

VOA: special.2009.01.06

The pasture is then kept empty until the grass grows to more than fifteen centimeters high.

VOA: special.2010.01.19

The pitch has more grass on it than I have seen at Lord's for many years.

BBC: Jonathan Agnew column

Less grain, more grass, lighter cattle.

BBC: Smaller, fewer, thinner - the future for American beef?

In order to get people to farm, thus providing local food (you know, local is good, right?), in a place which is snow and ice for half the year it is necessary to put up huge trade barriers to food coming in from places with more grass and more cows.

FORBES: The Great Norwegian Butter Famine