{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,6]],"date-time":"2026-03-06T04:02:51Z","timestamp":1772769771355,"version":"3.50.1"},"reference-count":44,"publisher":"Oxford University Press (OUP)","license":[{"start":{"date-parts":[[2026,1,1]],"date-time":"2026-01-01T00:00:00Z","timestamp":1767225600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,1,8]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>Three experiments were conducted to determine if nitrogen is a limiting factor for growth performance when feeding low protein, amino acid (AA) fortified diets and determine the effects of standardized ileal digestible lysine to crude protein (SID\u00a0Lys:CP) ratio on growth performance of 11- to 25-kg pigs. In Exp. 1,981 pigs ([Fast Large White \u00d7 PIC L02] \u00d7 PIC 800; initially 10.3\u2009\u00b1\u20090.19\u2009kg) were used in a 21-d study. Diets were corn-soybean meal-based consisting of: 1) a low level of feed-grade AA with a SID Lys:CP ratio of 6.0%; 2) a moderate level of feed-grade AA with a SID Lys:CP ratio of 6.5%; 3) a high level of feed-grade AA with a SID Lys:CP ratio of 7.0%; 4) diet 3 with added diammonium phosphate (DAP) added to achieve a SID Lys:CP ratio of 6.5%; and 5) diet 3 with L-Gly added to achieve a SID Lys:CP ratio of 6.5%. Average daily gain (ADG) was unaffected by dietary treatment but gain:feed ratio (G:F) decreased (linear, P\u2009=\u20090.002; quadratic, P\u2009=\u20090.054) as SID Lys:CP ratio exceeded 6.5%. Adding DAP or L-Gly to the high feed-grade AA diet increased (P\u2009\u2264\u20090.003) G:F compared to pigs fed the high feed-grade AA diet. In Exp.\u00a02, 4,167 pigs (337\u2009\u00d7\u20091050, PIC; initially 13.0\u2009\u00b1\u20090.27\u2009kg) were used in a 14-d study. Diets were corn-soybean meal-based, and treatments arranged in a 2\u2009\u00d7\u20095 factorial with main effects of SID Lys (1.15 or 1.30%) and SID Lys:CP ratio (6.00, 6.22, 6.46, 6.72, and 7.00%). Overall ADG was unaffected by dietary treatment; however, a SID Lys:CP \u00d7 SID Lys interaction was observed for G:F (linear, P\u2009=\u20090.012) where increasing SID Lys:CP ratio decreased (linear, P\u2009&amp;lt;\u20090.001) G:F at both SID Lys levels with a more pronounced effect in diets formulated to 1.15% SID Lys. Lastly, Exp. 3 used 5,059 pigs (PIC 800\u2009\u00d7\u2009Camborough and DNA 600\u2009\u00d7\u2009241; initially 11.0\u2009\u00b1\u20090.90\u2009kg) in an 18-d trial. Treatment diets were arranged in a 2\u2009\u00d7\u20096 factorial with main effects of dried distillers grains with solubles (DDGS; 0 or 15%) and SID Lys:CP ratio (6.01, 6.22, 6.45, 6.70, 6.97, and 7.26%). Overall, ADG was unaffected by dietary treatment, but a SID Lys:CP \u00d7 DDGS interaction was observed (linear, P\u2009&amp;lt;\u20090.001) where G:F increased then decreased (quadratic, P\u2009&amp;lt;\u20090.001) in diets without DDGS, whereas in the diets with DDGS, G:F decreased (quadratic, P\u2009\u2264\u20090.002) as SID Lys:CP ratio increased above 6.45%. In summary, a SID Lys:CP ratio greater than approximately 6.5% decreased G:F, but adding a protein or non-protein nitrogen source to low protein diets formulated above this ratio improves G:F.<\/jats:p>","DOI":"10.1093\/jas\/skag013","type":"journal-article","created":{"date-parts":[[2026,1,17]],"date-time":"2026-01-17T12:33:45Z","timestamp":1768653225000},"source":"Crossref","is-referenced-by-count":0,"title":["Effects of standardized ileal digestible lysine:crude protein ratio and the use of non-protein nitrogen on growth performance of 11- to 25-kg pigs"],"prefix":"10.1093","volume":"104","author":[{"given":"Jessica L","family":"Smallfield","sequence":"first","affiliation":[{"name":"Department of Animal Sciences and Industry, College of Agriculture, Kansas State University , Manhattan, KS 66506-0201,","place":["United States"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Mike D","family":"Tokach","sequence":"additional","affiliation":[{"name":"Department of Animal 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