i would have thought whoever and whatever birds you bring in you are entering a lottery as one lofts level of immunity differs from the other i maybe wrong just something i was lead to believe. Also the fact of buying birds is a lottery as you dont know if winners are going to be bred or there going to race and be winners.
dont normally if there going to lay they dummy eggs will motivate them to lay aswell,once you see if theres 3 eggs take the dummys away but if not leave them there for 18 days and slip a young bird underneath to allow them to bring one up
i realised that but i thought you meant concerning herbs and vegetables,not like other addiatives such as honey,glucose and electrolights! Another good additive to tea is the use of chopped onion!