I agree, check with your Dept of Ag. They're usually good folks. Info should be available on their website, also.
USDA is not interested in someone doing less than 1000 birds. Here in Oregon, neither is the state Ag Dept. As long as you process and sell on the farm, that is. No taking offsite and selling, like at farmer's markets. How the State guy explained it at a seminar I was just at......when they buy at a farmer's market, they (the customers) assume you're inspected or certified. When they come to the farm to pick up the butchered birds, they can see your set up with tarps and tents or whatever you have and decide for themselves if your level of cleanliness is up to standard