I gather horse manure into piles located near gardens or around the paddock and "the gals" take over manure management composting AND harrowing as they search for bugs. "The gals" are 2 full sized Barred Rock hens, 3 full sized Aracana's and one banty Lacey.... I like at least 2 hens per horse but 3 per horse is better. We have 10  acres, mostly mountain and forest, so there is plenty of room for chickens.They are VERY industrious creatures, lining up at their door early so that they can hit the piles hard, and voluntarily retiring to their coop as dusk falls.

They break down the poop balls, turn it over and remove any bugs they find - including LOTS of fly larva and even the flies if they can catch them.

If they get bored with the poohs, they wander the property eating earwigs, ants and other critters. The organic kitchen compost pile is a treasure trove for them.

The downside is that hens can dig in gardens that aren't screened or rock mulched, and can be pests in freshly planted flower beds (they are competitive diggers), but are also easy to control with bird netting. They also dream of joining you in the kitchen, so don't make the mistake of bringing them inside unless you intend to let them in regularly! Phil loves birds and kept our first chicks in the mud / laundry room until they were almost mature, and they decided it was their room, returning to lay eggs on the dryer.... we down-sized the cat door to keep them out! They tap on the French doors in the kitchen for treats, but are fairly polite about it. The dogs do great with them, although one tenants' dog, a true egg sucker, follows them around watching their feathered hineys, waiting for dinner to pop out.

We pour a few bags of laying mix into their hanging feeder a year, and built a hen condo in an 8x8 chain link dog kennel that is covered with no-climb top and bottom; the floor is layers of old grass hay (raked off the hay barn floor) placed over the refuse; the floor composts itself and is dug out once a year for garden mulching.

The dog kennel "coop" contains a two old small dog houses and two large white supplement buckets with old grass hay in them for "laying boxes", and we have 1 inch fallen branches several feet off the ground in a few places for the birds to roost on. We're in coastal Northern California with a relatively mild climate, and intend to eventually build a solid walled hen house, but the girls do fine in their tarp covered abode (covered roof and two covered sides) for now. The Dracaena's and the Banty Lacy sleep in the dog houses, and the barred rocks roost.

Do the girls really contribute to the place? Definitely!! In addition to turning and breaking down the manure, my fly populating is about 20% of what it was before, and the hens keep down the ants, earwigs and spiders (I don't mind spiders though).

Best thing is the delicious fresh eggs, 1 egg per hen per day much of the year. We end up with lots of extra eggs, super supplement for the 2 dogs and 3 cats -  even the parrots love eggs. Fresh yard laid eggs are so much better than "store bought" that there is no comparison! And I'm not supporting the caged hen farming industry.... I love my girls, and feel horrible for their caged sisters....