The best we have found is, I'm afraid, prickly. A mixed hedge which includes a high proportion of hawthorn, planted close, is good. Animals love it, birds can nest and roost in it, and eat the berries, it grows fairly fast and shelters slower growing species as they grow. Best to also have other plants such as hornbeam or beech, as these hold their leaves in winter. Please please don't plant Lawson Cypress
. So many murders and court cases seem to be sparked by that stuff, it grows too big, and doesn't provide anything that anything can eat. It does supply wind protection though (until it blows over) and somewhere for birds to shelter and nest. Oh and a hunting ground for insectivorous birds such as tits and goldcrests.
While you're at it, you might go the whole hog and plant a wildlife hedge, with a wide variety of different species, to provide nectar, fresh green leaves, berries. You will need to fence off the hedge from sheep as it grows, otherwise they will graze on it as high as they can reach. Cattle love pulling up newly planted hedge too.
If it's windy where you are, and you're feeling rich, you could put up a stretch of windbreak netting to protect the young plants as they grow, and to provide the windbreak effect for your flock until the hedge is big enough. It makes a big difference to how quickly the plants will grow. Protect from voles too - voracious wee devils