I had yb sickness for 3-4years and could not stop it reoccurring ,however whilst in hospital recovering after an operation a fancier friend who is also a gold cup winner visited me and gave me some very good books to pass my time,whilst reading about a certain German fancier he referred to I am sure he called it bogatar ? In other words Colostrum, I gave it to my breeders and then the weaned youngsters 2-3 times weekly put them on deep litter and never had a problem for years now ,I am sure we cause the problem sweeping the lofts and causing the virus to go airborne birds can't handle the dust thus the problem ,however I will stick to what works for me and the very successful German Fancier ,Atb Mick