There are a few key factors to consider-
First- What type of grazing animal are you using? For example, sheep will graze down a pasture far shorter than
cattle. So sheep can follow cattle without any recovery time. But for cattle to follow sheep, I would say 8 weeks is a good minimum. Horses, IME, are erratic in their grazing, leaving many areas long and others clipped very short, so do not work as well as other species for pasture management.
Second- When in the growing season? In May and June, when our pastures are growing at their fastest, I would say two weeks is enough rest on fertile, well irrigated ground. But by September, the resting time needs to be more like 6 weeks, as the pasture growth rate has slowed down. This variable of changing pasture growth rates is key.
Third- How hard are you going to graze a given area? For cattle, a rule of thumb I like, is put the cows in when the grass is knee high. Take them out before you can see their hooves. So they graze it down from 15" to 4", then you let it recover. If they graze it shorter than that, the pasture plants suffer a lot of stress and will regrow much more slowly. On the other end of the spectrum, if the pasture gets overgrown and tough, you will need to keep the animal pressure on for longer in order to get it all grazed down evenly, and the result will be a much more closely grazed pasture. Otherwise you will have large areas of dead tough grass that you animals will not eat, which has the effect of reducing your acreage.
The resource I reccomend most is Management Intensive Grazing by Jim Gerrish. He has taken the work of Voison and Hogsdon, and really advanced the understanding of pasture management. As good a book as they come, IMHO.
Also,
Alan Nation publishes the Stockman Grass Farmer
magazine, an invaluable resource to those new to grass-based livestock management.
Hope those generalizations help you out a bit, I am out moving electirc
fence and rotating cows at full speed this time of year. It is truly a joy to manage pasture in this way. The animals are so vibrantly healthy, and the soil fertility increases in ways you can see. Farming at its best! Feel
free to ask any questions you may have.