Housing farm animals indoors can be pretty horrendous. They poop and pee and if they must be kept confined for long periods, say, because the weather is too cold or wet or stormy outside, the conditions can get, quite frankly, rank. There are a couple of systems that get over this problem.
The totally aerobic system
I saw this system for myself in South Africa in the farm where we got our baby broiler chicks for our fish/chicken farms. In the cage where the farmer kept his laying hens and roosters, he put down a deep bed of saw dust of the type that comes from a lumber mill. It is quite coarse, unlike, for instance, sanding sawdust or even the sawdust from a table saw. Chickens have solid urine (the white part of a chicken poo) but even so, left alone, the chicken houses will become pretty rank in short order. The bedding becomes anaerobic and the anaerobic break down of organic material produces Carbon dioxide, methane and ammonia. It is an eye-watering, lung-damaging combination. So what did the farmer do.
He had his employees turn the bedding every day. This kept it aerobic. We got to know the farmer as we bought chicks every two weeks and eventually he let us come and see his system. We were amazed at how odorless it was. It was toward the end of a cycle and the bedding was a fine, brown material with the odor of fresh earth. The farmer told us that this system pretty well eliminated any disease problems. I suppose a pathological bacteria falling into this mass of micro-organisms would be like dropping a pet rabbit into the middle of Africa. The other disease control effect must have been the elimination of ammonia. Ammonia will damage the lungs of any animal breathing it in and leave the lungs open to infection.
Composting barns are also used for cattle. Here is an extreme example of a composting barn in which the cows are kept indoors 24/7/365. It is more common to have cows indoors only when the weather is too inclement to have them outside.
An anaerobic/aerobic system
I read about this one in The Omnivores Dilemma. It was developed by Joel Saladin in his farm Polyface in the Shenandoa valley in Virginia, USA. Joel keeps his cows indoors for the three winter months. Instead of aerating the bedding, he adds a layer of wood chips or hay as needed. But before adding new bedding, he scatters a pail of corn over the old bedding. Presumably the system works since there is no smell of Ammonia. The upper layers of this bedding would be aerobic so the upper layers are probably incorporating the ammonia produced by the lower levels. After three months it is time to send the cows out to pasture. When they have gone, he sends in the pigs. He calls them his pigaerators. As they go in search of the alcoholic kernels of corn, they root around and stir up the bedding, aerating it. The bedding heats up, probably killing any pathogens and results in an odorless rich compost for spreading on the fields.
There is one other example of indoor animals at Joels farm. His son grows rabbits for meat. Rabbit urine is very strong and if kept indoors, you would have to be continually cleaning to stop the rabbits damaging their lungs from the ammonia their urine produces. So, once again they put down a thick layer of wood chips or hay under the pens. Here they keep the layer aerobic by introducing chickens. The chickens forage in the litter for grubs and insects and keep the wood chips aerobic.
As I said at the beginning, holding farm animals indoors can be horrendous but it can also be very good for the animals. As usual, with all farming systems, the devil is in the detail.
