Rather than just increasing protein levels in feed that may not be digestible, it is best to use a moult supplement consisting of digestible proteins which contain adequate levels Methionine and Lysine. Biotin, and other B vitamins, A,D,E are all important during moult. It is a hassle free way of ensuring these are available by professional formulators rather than purchasing the lab equipment necessary for testing food stuffs to make sure they have adequate amounts. I have little confidence in large commercial feeds based upon what I have seen over 30 years. All one needs to do is look at FDA recall lists to see adequate amounts of nutrients are not always present, among other things, in livestock feeds which can present problems.