I used to raise chickens and sell the eggs. I also raised roosters and sold them as butchered fryers. I also milked cows and sold the cream. As long as you keep the pens cleans and put straw or some other type of bedding in there it doesn't stink, no flies unless you never clean it. I live on a farm and always kept the chickens in the pen, so no poo at the house or in the yard. Those eggs had the light yellow yolk which all my customers wanted because they didn't like the taste of eggs from chickens that ate mustard and a few other choice weeds which went to the egg yolk. I sold many dozens per week, had them yr round --no heat in bldg-they got hot water to drink and mash to eat. There were enough chickens in the bldg that they made their own heat. Just had to pick the eggs more often in the winter so they didn't freeze. Had an egg washer, never candled an egg because I never had roosters with them. I always sold my yr and half old hens to a neighbor and she kept the last ones for about 6 yrs til they died. She got eggs everyday from them yr round.