Ill. Admin. Code tit. 35, § 502.103
An Animal Feeding Operation is defined as a Large CAFO if at least the numbers of animals specified in any of the following categories are stabled or confined:
| Number of Animals | Kind of Animals |
| 700 | Mature dairy cows, whether milked or dry |
| 1,000 | Veal calves |
| 1,000 | Cattle other than mature dairy cows or veal calves. Cattle includes heifers, steers, bulls, and cow/calf pairs. |
| 2,500 | Swine, each weighing 55 pounds or more |
| 10,000 | Swine, each weighing less than 55 pounds |
| 500 | Horses |
| 10,000 | Sheep or lambs |
| 55,000 | Turkeys |
| 30,000 | Laying hens or broilers, if the Animal Feeding Operation uses a liquid manure handling system |
| 125,000 | Chickens (other than laying hens), if the Animal Feeding Operation uses other than a liquid manure handling system |
| 82,000 | Laying hens, if the Animal Feeding Operation uses other than a liquid manure handling system |
| 30,000 | Ducks, if the Animal Feeding Operation uses other than a liquid manure handling system |
| 5,000 | Ducks, if the Animal Feeding Operation uses a liquid manure handling system |
(Source: Amended at 48 Ill. Reg. 3196, effective February 15, 2024)