If you know you have yeast it is best to use something meant to treat yeast. And if your hens have yeast in the reproductive tract, the only way to treat that is with fluconazole or ketoconazole and that is because they work systemically and nystatin and miconazole only work on yeast it touches...
Nystatin can be used to treat some strains of candida in poultry.
According to most veterinary formularies and references, the most common Nystatin dose is 200,000 to 300,000 IU/kg two or three times a day. Lafeber vet recommends 300,000 IU 2-3 times a day, so that is what I will base my...