I rescued a couple of older ducks (maybe around 4 months old or so?) and I gave them a Vitamin B supplement (like the cattle vitamins), salmon, peas, and brewer's yeast. It took a couple of weeks, but their beaks started to gain their color back. I also made sure I was feeding them a good water fowl food! Good luck!Hi! I think I am having the same issue. Did the cattle supplement work? Thanks so much!