I think a little more clarification needs to be made on this comment. What are these "Best management practices "you speak of. I've had great success running large groups of lambing ewes, 200+, in/with large groups of calving cattle,100+, while maintaining an 180% weaned lamb crop. I have found them to be very complementary. One of the biggest costs in small ruminant production is the loss of gain that is caused by intestinal parasites. Cattle are dead end hosts to the same parasites that plague small's and the same is true with small's as a dead end host to cattle parasites. Cattle with sheep can/will significantly reduce the need to worm both species while improving the average daily gain of both. I have found this to be the key to having a low input small ruminant operation in a humid climate. I cannot speak to any of the diseases that were brought accept to say that I have had none. Run them together.The main point that I was trying to make is that with best management practices, sheep and cows should not ever be grazing the same pastures at the same time. They have different grazing needs, and as such, need to be managed separately
Dairy cows, and cattle in general, are a higher value class of livestock, so I do not want to make less than optimal use of my pasture resource feeding sheep. Sheep and cows are largely competitive with one another, so I am taking on extra labor to deal with two species, and also raising a lower value animal with sheep. For these reasons I do not raise sheep anymore, and just keep my stocking numbers as high as my pasture will support with cows.
Sheep are excellent improvers of pasture. With proper grazing management, they will turn an average pasture into a dairy quality pasture faster than any other class of livestock. So it is great to run sheep for a few years without cows, simply to get your pastures where they need to be. Sheep have much lower quality requirements than cows so they will thrive in situations where cows would struggle. All the while improving the pasture.