We use a farm sitter for when we go away. She comes 4 times a day but doesn't live in. She looks after 4 dogs, 30 sheep, 2 horses, 4 geese and 2 stable cats!
However she like many sitters are horse specialists and cover other animals like dogs and farm animals as a by product (they are easier than horses!).
Some peeps with a few livestock will tend to rely on family and friends, there is still a market for it but I think its horses that make the need to get in a proper paid sitter and horsey peeps are more used to paying others to do things in respect of the animal (farrier, vet, horse dentist etc)
So if you would be prepared to get some experience with horses I think the market would be much wider.