Density-Independent does not effect the sheep like some other animal. Due to there large wooled coat cold weather does not bother them. But sometime sheep get heat stress because they are less tolerable than most animals.
Some Density-dependent factors for sheep would be availability to food. Also decease in a flock could bring down the population of the sheep.
Reproducing is important and increase with the amount of resources. Including food and a place where the baby sheep would not get harmed. The population would increase with more births.