Debbie Burnette, who has Cardigan Welsh Corgis, highly recommends goats for starting dogs. When I questioned this because their groups break apart very easily. She responded that yes they break apart, but they don’t take off. So, the dog can easily put them back together again. A good alternative when there are no appropriate sheep available. Also, although sheep are known for grouping much better than goats, so many sheep we see today, actually group worse than goats. In some areas, it seems like there are not heavy wooly sheep available to work. No one wants to sheer. Therefore, only light haired sheep which are bad for starting GSDs on are available. However, haired goats can be heavy and therefore are a much better choice for GSDs than haired sheep. If all you have is light sheep in your area, seek out goats.
Cow dog folks often start dogs on goats and then progress to cattle. They find this produces a much better on dog then starting on sheep. Goats behave much more like cattle than they do sheep and aren’t as intimidating for a starting dog as are cattle. After they have a handle on the dog and it has gained in confidence, then they move on to cows.