So i have over 400 rare breed chickens and a respiratory illness has begun to spread with the purchase of what i didnt realize were sick birds. I have tried tylan 50 fed directly to the chickens twice daily and the dosage changes based on size but as it spreads i am unable to keep up with getting each bird the proper amount twice daily. I need a better option such as the now unavailable duramycin-10 to mix into their water. Is there an alternative since i know they took this off the shelf. I can get the liquid duramycin from tractor supply but i cant find any threads about mixing it in water. I surely cant inject lets say 50 birds twice daily thats just fiscally impossible. What is everyone using to combat these illnesses on a larger scale?