It WAS an obvious oversight by the Vet, who really should have thought things thru and seemingly didn't. Its not clear to me that he/she understood the formulation differences between a "layer" feed, "scratch", or any other (grower, rooster maintenance, game bird, etc) in order to have had the...
Not actually a course.
OK, I'm sure its a course somewhere. Here in Florida, UF has a decent reputation for turning out Vets. You can get your degree, and a Certificate in Food Animal Medicine, without a dedicated poultry class...
Fun as it may be to pick on this vet, its entirely possible they are a qualified generalist. Their ignorance on the topic of poultry should not be imputed to be ignorance on everything animal, or they would never have obtained their license. Possible they are highly qualified on dogs and cats...
Get a new Dr.
your current vet has recommended deliberately starving the birds to the point that it ceases their perfectly normal egg laying cycle. Forgot to mention that said birds will first cannibalize their own bodies - including leaching calcium from their bones - to support more or less...