[Stereo]

Grass is like most things, it grows in a 'S' curve. If you mow it too tight, it takes a long time to come back as there is not enough leaf to take in energy from the sun. If you let it go too far, it's growth slows. So you want to keep it in the middle somewhere. I always feel most grass is grazed way too tight. About 4cm is a good basis I would think.

Aside from worms, you should also consider the effect that animals have on beneficial plants in the sward. There is much research on the benefits of plantain to sheep and they will seek it out. If you keep the sheep in the same plot, they will just keep snipping off the new plantain leaves and eventually, this kind of treatment will kill most plants. A couple months of rest will allow those plants to establish themselves again without being hammered.

Our farm has been let to 2 graziers for many years by my father. One moves his sheep from field to field over 20 acres. The other leaves the gates open and they graze back and forth as they wish. It's interesting to compare the pastures after 12 or so years of this as the pastures that are given rest are far more diverse than the others which are going to thistles and nettles.

[Moos and ewes]

Main reason is to break the cycle in worms or if turning out fresh lambs to field used the year before will have a higher chance of picking up coccidiosis,
If this is not possible making hay or cutting grass and removing it will freshen field that or grazing with cattle as sheep and cattle don't pass worms.
The old saying I go by is you shouldn't hear the church bells more than 4 times with them in that field so idealy every 3-4 weeks move to another field, cuts down worms a bit. And slows grass to refreshen. They didn't have wormers years ago so guess one way they used.

[landroverroy]

No you don't have to, and most people don't have the luxury of having sufficient pasture that they can rest it long enough to make a real difference.
However, if on weaning your lambs, you worm them and put them on  absolutely clean grass, ie grass that hasn't seen a sheep for at least 2 years, then you will achieve a growth rate unsurpassable by any creep or supplement feeding.

[ScotsGirl]

My problem seems to be timing. I have use of approx 12-14 acres but only bits at certain times of year. I start out planning to rotate sooner but the weather usually throws a spanner in the works and grass doesn't grow at the rate I expect. I've dropped down to about 20 sheep but will increase next month with lambs. Quality definitely isn't there.

[wonderwooly]

Hi.
We try to rotate, but I always find it a struggle as the time of year also dictates whether our fields are very dry or very wet,  so although I could
take a line on a map and split it up into neat sections it would not correspond with what is really possible at that moment in the year. And it varies year on year.

I have seen though that the sheep really like the forest areas especially from Oct onwards. I had wondered whether this might give them a bit of something else when they are down to a smaller winter pasture and give more time to rest other fields in winter? Anyone with experience of running sheep in woodland sometimes ? I'm wondering whether it is worth fencing it.
Also just a thought does the frost impact on worm counts? ie if the field is grazed hard
in sept then left for a good frost and possibly frost seeded could this help?
Its an open question, I have no idea, just a thought.