At the risk of being incredibly insulting, the sheer amount of ignorance and yes, stupid, in this ages old thread is frightening to me, when I consider that some portion of these commentors likely vote, helping to set the policy direction for their cities, counties, state, and nation...
@Nuescolina you are not allergic to "shellfish". You are, at best, allergic to something commonly found IN shellfish, some part of their overall chemical makeup, which is likely concentrated in some parts of the offending ingredient more than others. Many people with allergies to "shellfish" (shrimp, lobster, crab, etc) may eat mollusks (clams, oysters, mussels, etc) without any concern whatsoever. A shrimp's carapace, largely chitin, does not chemically resemble a mollusk's shell in any significant ways.
Other people can't eat mollusks, but CAN eat shellfish. Interestingly, some of those persons can eat mollusks harvested from different locations without incident. In those cases, the person is not allergic to the mollusk itself, but rather something the mollusk consumes in the environment and concentrates within it. Typically, this is some toxin produced by another species present in the local waters - the production of various dinoflagelates, domoic acid from various plankton, brevitoxins (in large quantity, these are what makes "red tides" so dangerous, but in tiny quantities, they are almost always present in US Gulf Waters), saxitoxins in the New England waters, Northern CA to AK, etc....
Still others *think* they are allergic to both due to prior cross-contamination - fish mongers and restaurants tend to store them side by side, and prepare them with the same methods and tools.
And some people truly are alergic to both the flesh of shellfish and the flesh of mollusks due to a common shared family of molecules, most commonly the unique expresion of tropomyosins found in those species. You have tropomyosins (expressed differently) in yourself, by the way - they are part of the process that controls skeletal muscle movements. Again, DETAILS MATTER.
Now, for practical reasons, it may be perfectly adequate to claim a "shellfish" allergy, because its largely unimportant in your personal food consumption as to what, specifically, you are *actually* allergic to. Alternative foods are easily sourced, there is normally no need for you to have greater understanding in your day to day life.
That ignorance does not, however, assist you in determining whether something that consumes a food you are alergic to will then move the offending molecule/class of molecules into itself in a way which is potentially harmful to you, or if instead its biological processes denature the molecule in ways which render it safe to you - or pass the chemical thru their digestive tract and out into waste - or store it in a portion of themselves that you don't consume.
To begin with the adage "you are what you eat" (which conveys an important, if inexact, message) and then jump to the conclusion that you can't eat things which have eaten things which you want (or need) to avoid is a logical fallacy so great I lack words to convey it. To put it in vary basic terms, apple seeds contain cyanide, yet we eat apples. It vary rarely kills any of us, and most for reasons other than cyanide poisoning.
Life is **COMPLICATED**.
To answer your question, you are going to have to put more effort into understanding yourself, before you can then do the research to discover the answer you seek regarding the feeding of your fowl.
