First of all thanks for posting this peter.j
This is no cure just an expensive way of clearing a pigeons crop.
The fasting and feeding light and more importantly the resting of the pigeons for a week or so has been covered numerous times on other threads, this is all that’s required.
The holding of corn is only one symptom of this virus, don’t get fooled into thinking once they're eating and digesting proper they're cured...they're not. Treat them like you would treat yourself suffering from a bout of flu, the shits & vomiting goes but you ache like **** for days after.... rest is all important.