Keeping livestock on pasture is great, but it comes with some challenges. One that I constantly watch for is predation. So far my chickens have done very well on pasture with only electric poultry netting to protect them from predators. Occasionally one gets stupid and gets out of the protective fence and not back in before dark. I used to chase them around like a crazy person every time they got out, but there are a few who just will not stay in. Last night one of the "suicide gang" didn't make it back through the fence before dark. Reddy the fox (or some other night time opportunist) eliminated them from the gene pool and put their molecular resources back into community circulation.
The other challenge we have been facing recently is grass, or more precisely, the lack of grass. We have had about 3/4 of an inch of rain in the last 8 weeks. Not a good situation for growing grass. I did some measurements today and the paddocks coming up in the rotation are about half as high as they should be. The paddock we left 20 days ago, which should have grass at least a foot tall, is mostly brown with some spots of grass standing three to four inches. We should be back on that paddock in about 10 days, but there wont be anything for the critters to eat. I still have about two months of grass left, counting my winter stockpile, but that won't take me to January. If we don't get extremely lucky and have some consistent rain move in, paired with a nice long warm fall, I'll be at least two months short of grazing. That means one of two things, I can reduce the number of grazers (which extends the amount of grass), or I can buy more hay. This is the second year this has happened. We got through the first year without a problem, but we have more livestock this year. Not sure what I will do, but it will hurt either way. We are, however, in much better shape than our neighbors. This year, like last year, they started feeding hay in August. They run about the same stocking density as I do (stocking density = the number of pounds of livestock per acre) but they set graze rather than using a rotational system. Works fairly well when the weather cooperates, but it is a disaster when it gets dry or otherwise stressed.
I've explored this and other grazing issues in my soon to be released e-booklet about grazing.