Keratins as Sources of Protein for the Growing Chick: 3. The Metabolizable Energy and Amino Acid Composition of Raw and Processed Hog Hair Meal with Emphasis on Cystine Destruction with Autoclaving

Abstract

RAW ground hog hair, when used in semi-purified rations as a sole source of protein, failed to support chick growth regardless of amino acid supplementation; processing the hair (30 minutes at 148°) resulted in a meal which when supplemented with deficient amino acids supported growth equal to that observed with isolated soybean protein (Moran et al., 1967). Similarly, raw feathers, source of another keratin protein, also will not support chick growth, but upon autoclaving (30 minutes at 142°) proves to be a valuable source of dietary protein when balanced (Moran et al, 1966).One outstanding difference between the raw and processed feather meals is the drastic reduction in cystine content (Gregory et al., 1956; Moran et al., 1966). Menefee and Bartulovich (1965) accounted for the extreme insolubility of native keratins on the basis of large numbers of crosslinkages; likewise, Earland and Knight (1955) suggest that the large molecular weight of …