{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,27]],"date-time":"2026-01-27T15:23:52Z","timestamp":1769527432956,"version":"3.49.0"},"reference-count":49,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2016,2,19]],"date-time":"2016-02-19T00:00:00Z","timestamp":1455840000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Nutrients"],"abstract":"<jats:p>Poultry feathers, consisting largely of keratin, are a low-value product of the poultry industry. The safety and digestibility of a dietary protein produced from keratin (KER) was compared to a cysteine-supplemented casein-based diet in a growing rat model for four weeks. KER proved to be an effective substitute for casein at 50% of the total dietary protein, with no changes in the rats\u2019 food intake, weight gain, organ weight, bone mineral density, white blood cell counts, liver glutathione, or blood glutathione. Inclusion of KER in the diet reduced total protein digestibility from 94% to 86% but significantly increased total dietary cysteine uptake and subsequent liver taurine levels. The KER diet also significantly increased caecum weight and significantly decreased fat digestibility, resulting in a lower proportion of body fat, and induced a significant increase in blood haemoglobin. KER is therefore a safe and suitable protein substitute for casein, and the cysteic acid in keratin is metabolised to maintain normal liver and blood glutathione levels.<\/jats:p>","DOI":"10.3390\/nu8020104","type":"journal-article","created":{"date-parts":[[2016,2,19]],"date-time":"2016-02-19T11:29:39Z","timestamp":1455881379000},"page":"104","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":11,"title":["Cysteic Acid in Dietary Keratin is Metabolized to Glutathione and Liver Taurine in a Rat Model of Human Digestion"],"prefix":"10.3390","volume":"8","author":[{"given":"Frances","family":"Wolber","sequence":"first","affiliation":[{"name":"School of Food and Nutrition, Massey University, Palmerston North 4442, New Zealand"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Michelle","family":"McGrath","sequence":"additional","affiliation":[{"name":"School of Food and Nutrition, Massey University, Palmerston North 4442, New Zealand"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Felicity","family":"Jackson","sequence":"additional","affiliation":[{"name":"Riddet Innovation, Massey University, Palmerston North 4442, New Zealand"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kim","family":"Wylie","sequence":"additional","affiliation":[{"name":"School of Food and Nutrition, Massey University, Palmerston North 4442, New Zealand"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Anne","family":"Broomfield","sequence":"additional","affiliation":[{"name":"School of Food and Nutrition, Massey University, Palmerston North 4442, New Zealand"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2016,2,19]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"673","DOI":"10.1093\/jn\/33.6.673","article-title":"Nutritive value of keratin; effect of source, particle size, and method of grinding","volume":"33","author":"Newell","year":"1947","journal-title":"J. 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