This is undoubtedly linked to the fact that the results of experimental application of these antibodies in poultry have not always been consistent. Another interesting point is that the number of studies concerning possible beneficial effect of the use of IgY in poultry is quite low compared to studies in other animal species. Indeed, despite the fact that the European legislation does not prohibit the use of egg products in feed, since the mad cow crisis, there is still a wide spread misconception that egg yolk antibodies can not be used in chicken feed, just like animal flour in cattle feed