Abstract: A leather hydrolysate metal proteinate to be used as a metal nutrient for an animal feed. Chrome tanned leather scrap and shavings are heated in an aqueous solution with an alkali material to produce a water soluble, low molecular weight protein hydrolysate and insoluble chromium compounds which are subsequently separated from the hydrolysate. The hydrolysate is then oxidized to remove any objectionable trace organic residuals from the tanning process, and a di- or tri-valent water soluble metal salt is mixed with the hydrolysate to provide a metal proteinate. The metal proteinate, either as a liquid or a dried powder, can be used as animal or aquaculture diets.