Chickens like all bird species have IgY antibodies that are very stable and found in the yolk. Gallus Gallus domestica is the Latin name of the Chicken.Chicken yolk polyclonal Immunoglobulin Y (abbreviated as IgY) is a type of immunoglobulin which is the major antibody in bird, reptile, and lungfish blood. It is also found in high concentrations in chicken egg yolk. As with the other immunoglobulins, IgY is a class of proteins which are formed by the immune system in reaction to certain foreign substances, and specifically recognize them.