{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,23]],"date-time":"2026-03-23T03:44:42Z","timestamp":1774237482749,"version":"3.50.1"},"reference-count":34,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2025,4,23]],"date-time":"2025-04-23T00:00:00Z","timestamp":1745366400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"CAPES PROEX","award":["88887.8444747\/2023-00."],"award-info":[{"award-number":["88887.8444747\/2023-00."]}]},{"name":"CAPES PROEX","award":["117\/2022"],"award-info":[{"award-number":["117\/2022"]}]},{"name":"CJ do Brasil","award":["88887.8444747\/2023-00."],"award-info":[{"award-number":["88887.8444747\/2023-00."]}]},{"name":"CJ do Brasil","award":["117\/2022"],"award-info":[{"award-number":["117\/2022"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Animals"],"abstract":"<jats:p>This study aimed to evaluate the effects of the standardized ileal digestible tryptophan-to-lysine (SID Trp\u2013Lys) ratio through the supplementation of different levels of L-tryptophan on pig performance and immune response following an LPS challenge. A total of 120 entire male pigs, with an average body weight of 16.5 \u00b1 0.50 kg, were allocated in a randomized block design with four treatments, ten replicates per treatment, and three animals per experimental unit. The experimental treatments consisted of SID Trp\u2013Lys ratios of 16%, 18%, 21%, and 24%, achieved through L-tryptophan supplementation. The evaluated performance parameters included the final body weight (BW), average daily gain (ADG), average daily feed intake (ADFI), and feed conversion ratio (FCR). Blood samples were collected on day 21 to determine serum serotonin levels, and on day 26, pigs were inoculated with LPS to induce an immune challenge, followed by blood sampling to assess cytokine responses. The results showed that pigs fed the 16% SID Trp\u2013Lys ratio exhibited a lower FBW (p &lt; 0.05). The SID Trp\u2013Lys ratios influenced performance parameters, with quadratic responses (p &lt; 0.05) observed for the FBW and FCR, where the highest FBW and lowest FCR were recorded at 22.05% and 21% SID Trp\u2013Lys, respectively. A linear increase (p &lt; 0.05) was observed for ADG, with a trend for a linear increase (p = 0.056) in ADFI. No effects (p &gt; 0.10) of the SID Trp\u2013Lys ratios were detected on serum serotonin levels. An increase in cytokine levels (GM-CSF, IFN-\u03b3, IL-1\u03b1, IL-1\u03b2, IL-1ra, IL-4, IL-6, IL-8, IL-10, IL-12, IL-18, and TNF-\u03b1) was observed in pigs challenged with LPS (p &lt; 0.10) compared to non-challenged animals. An interaction effect (p &lt; 0.10) was detected for IL-2 and IL-18. SID Trp\u2013Lys ratios between 21% and 24% optimize growth performance in pigs from 16 to 33 kg and modulate the immune response under LPS-induced challenge conditions.<\/jats:p>","DOI":"10.3390\/ani15091194","type":"journal-article","created":{"date-parts":[[2025,4,23]],"date-time":"2025-04-23T03:43:37Z","timestamp":1745379817000},"page":"1194","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["SID Trp\u2013Lys Ratio on Pig Performance and Immune Response After LPS Challenge"],"prefix":"10.3390","volume":"15","author":[{"given":"Stephane Alverina Briguente","family":"Da Motta","sequence":"first","affiliation":[{"name":"Department of Animal Science, Federal University of Vi\u00e7osa, Vi\u00e7osa 36570-900, Minas Gerais, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0004-4295-5750","authenticated-orcid":false,"given":"Nathana Rudio","family":"Furlani","sequence":"additional","affiliation":[{"name":"Department of Animal Science, Federal University of Vi\u00e7osa, Vi\u00e7osa 36570-900, Minas Gerais, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Antonio Carlos","family":"Louren\u00e7o","sequence":"additional","affiliation":[{"name":"Department of Animal Science, Federal University of Vi\u00e7osa, Vi\u00e7osa 36570-900, Minas Gerais, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sergio Xavier Silva","family":"Junior","sequence":"additional","affiliation":[{"name":"Department of Animal Science, Federal University of Vi\u00e7osa, Vi\u00e7osa 36570-900, Minas Gerais, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Juliana Cristina Ramos","family":"Rezende","sequence":"additional","affiliation":[{"name":"CJ do Brazil, Piracicaba 13432-700, S\u00e3o Paulo, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3198-0155","authenticated-orcid":false,"given":"Melissa Izabel","family":"Hannas","sequence":"additional","affiliation":[{"name":"Department of Animal Science, Federal University of Vi\u00e7osa, Vi\u00e7osa 36570-900, Minas Gerais, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,4,23]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"165","DOI":"10.1016\/bs.acc.2019.08.005","article-title":"Tryptophan in health and disease","volume":"95","author":"Comai","year":"2020","journal-title":"Adv. Clin. Chem."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1873","DOI":"10.2527\/1992.7061873x","article-title":"Interactive effects of dietary levels of tryptophan and protein on voluntary feed intake and growth performance in pigs, in relation to plasma free amino acids and hypothalamic serotonin","volume":"70","author":"Henry","year":"1992","journal-title":"J. Anim. Sci."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"212","DOI":"10.2527\/2006.841212x","article-title":"Use of supplementary tryptophan to modify the behavior of pigs","volume":"84","author":"Li","year":"2006","journal-title":"J. Anim. Sci."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"IJTR-S2129","DOI":"10.4137\/IJTR.S2129","article-title":"L-tryptophan: Basic metabolic functions, behavioral research and therapeutic indications","volume":"2","author":"Richard","year":"2009","journal-title":"Int. J. Tryptophan Res."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Liu, G., Lu, J., Sun, W., Jia, G., Zhao, H., Chen, X., Kim, I.H., Zhang, R., and Wang, J. (2022). Tryptophan supplementation enhances intestinal health by improving gut barrier function, alleviating inflammation, and modulating intestinal microbiome in lipopolysaccharide-challenged piglets. Front. Microbiol., 13.","DOI":"10.3389\/fmicb.2022.919431"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"581","DOI":"10.1038\/nm.4117","article-title":"Regulating inflammation with microbial metabolites","volume":"22","author":"Marsland","year":"2016","journal-title":"Nat. Med."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"103493","DOI":"10.1016\/j.mcn.2020.103493","article-title":"Short-chain fatty acids (SCFAs) alone or in combination regulate select immune functions of microglia-like cells","volume":"105","author":"Wenzel","year":"2020","journal-title":"Mol. Cell. Neurosci."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"1303","DOI":"10.2527\/2005.8361303x","article-title":"The tryptophan requirement of growing and finishing barrows","volume":"83","author":"Guzik","year":"2005","journal-title":"J. Anim. Sci."},{"key":"ref_9","unstructured":"Rostagno, H.S., Albino, L.T., Donzele, J.L., Gomes, P.C., Oliveira, R.F., Lopes, D.C., Ferreira, A.S., Barreto, S.L.T., and Eucl\u00eddes, R.F. (2011). Brazilian Tables for Poultry and Swine: Composition of Feedstuffs and Nutritional Requirements, Federal University of Vi\u00e7osa. [3rd ed.]."},{"key":"ref_10","unstructured":"NRC (2012). Nutrient Requirements of Swine, National Academy Press. [11th ed.]."},{"key":"ref_11","unstructured":"Rostagno, H.S., Albino, L.F.T., Hannas, M.I., Donzele, J.L., Sakomura, N.K., Perazzo, F.G., Saraiva, A., de Abreu, M.L.T., Rodrigues, P.B., and de Oliveira, R.F. (2017). Brazilian Tables for Poultry and Swine: Composition of Feedstuffs and Nutritional Requirements, Federal University of Vi\u00e7osa. [4th ed.]."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"315","DOI":"10.1093\/jas\/sky401","article-title":"Immune system stimulation induced by Escherichia coli lipopolysaccharide alters plasma free amino acid flux and dietary nitrogen utilization in growing pigs","volume":"97","author":"McGilvray","year":"2019","journal-title":"J. Anim. Sci."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"2027","DOI":"10.1071\/AN15504","article-title":"Digestible tryptophan to lysine ratios for weaned piglets at 26 days of age","volume":"57","author":"Oliveira","year":"2016","journal-title":"Anim. Prod. Sci."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1686","DOI":"10.2527\/jas.2008-1348","article-title":"The effect of sanitary status degradation and dietary tryptophan content on growth rate and tryptophan metabolism in weaning pigs","volume":"87","author":"Lebellego","year":"2009","journal-title":"J. Anim. Sci."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"114","DOI":"10.1016\/j.livsci.2015.09.021","article-title":"Simultaneous determination of standardized ileal digestible tryptophan and lysine for barrows from 15 to 30 kg live weight","volume":"181","author":"Pasquetti","year":"2015","journal-title":"Livest. Sci."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"25","DOI":"10.1016\/j.livsci.2019.01.016","article-title":"The response of performance in grower and finisher pigs to diets formulated to different tryptophan to lysine ratios","volume":"222","author":"Liu","year":"2019","journal-title":"Livest. Sci."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"114342","DOI":"10.1016\/j.anifeedsci.2019.114342","article-title":"Estimating the standardised ileal digestible tryptophan requirement of pigs kept under commercial conditions in the immediate post-weaning period","volume":"259","author":"Capozzalo","year":"2020","journal-title":"Anim. Feed. Sci. Technol."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"594","DOI":"10.1017\/S1751731111001960","article-title":"Estimation of the tryptophan requirement in piglets by meta-analysis","volume":"6","author":"Simongiovanni","year":"2012","journal-title":"Animal"},{"key":"ref_19","first-page":"2646","article-title":"The tryptophan requirement of nursery pigs","volume":"80","author":"Guzik","year":"2002","journal-title":"J. Anim. Sci."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"47","DOI":"10.1016\/j.domaniend.2006.04.005","article-title":"Tryptophan enhances ghrelin expression and secretion associated with increased food intake and weight gain in weanling pigs","volume":"33","author":"Zhang","year":"2007","journal-title":"Domest. Anim. Endocrinol."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"skab356","DOI":"10.1093\/jas\/skab356","article-title":"Effects of dietary leucine and tryptophan on serotonin metabolism and growth performance of growing pigs","volume":"100","author":"Kwon","year":"2022","journal-title":"J. Anim. Sci."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"213","DOI":"10.1016\/j.livsci.2012.11.003","article-title":"Supplemental dietary tryptophan modifies behavior, concentrations of salivary cortisol, plasma epinephrine, norepinephrine and hypothalamic 5-hydroxytryptamine in weaning piglets","volume":"151","author":"Liu","year":"2013","journal-title":"Livest. Sci."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1270","DOI":"10.2527\/jas.2011-4537","article-title":"Standardized ileal digestible tryptophan-to-lysine ratios in growing pigs fed corn-based and non-corn-based diets","volume":"90","author":"Quant","year":"2012","journal-title":"J. Anim. Sci."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"90","DOI":"10.1016\/j.livsci.2015.02.012","article-title":"Optimum standardized ileal digestible tryptophan to lysine ratio for pigs weighing 7\u201314 kg","volume":"175","author":"Pedersen","year":"2015","journal-title":"Livest. Sci."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"3909","DOI":"10.2527\/jas.2015-9083","article-title":"Effects of standardized ileal digestible tryptophan: Lysine ratio on growth performance of nursery pigs","volume":"93","author":"Nitikanchana","year":"2015","journal-title":"J. Anim. Sci."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"37","DOI":"10.1016\/j.livprodsci.2003.09.005","article-title":"Modifications of protein and amino acid metabolism during inflammation and immune system activation","volume":"87","author":"Melchior","year":"2004","journal-title":"Livest. Prod. Sci."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1091","DOI":"10.2527\/2004.8241091x","article-title":"Chronic lung inflammation affects plasma amino acid concentrations in pigs","volume":"82","author":"Melchior","year":"2004","journal-title":"J. Anim. Sci."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"32","DOI":"10.1186\/1751-0147-50-32","article-title":"Blood concentrations of the cytokines IL-1beta, IL-6, IL-10, TNF-alpha and IFN-gamma during experimentally induced swine dysentery","volume":"50","author":"Kruse","year":"2008","journal-title":"Acta Vet. Scand."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1808","DOI":"10.1080\/21505594.2021.1948276","article-title":"An\u00e1lise do transcriptoma de PBMCs porcinos revela respostas imunomoduladoras induzidas por lipopolissacar\u00eddeos e intera\u00e7\u00e3o cruzada da sinaliza\u00e7\u00e3o do receptor imune e glicocorticoide","volume":"12","author":"Li","year":"2021","journal-title":"Virulence"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"417","DOI":"10.1089\/jir.1996.16.417","article-title":"Interferons and other cytokines in bacterial infections","volume":"16","year":"1996","journal-title":"J. Interferon Cytokine Res."},{"key":"ref_31","first-page":"4069","article-title":"Tryptophan alleviates lipopolysaccharide-induced liver injury and inflammation by modulating necroptosis and pyroptosis signaling pathways in piglets","volume":"34","author":"Gu","year":"2023","journal-title":"Anim. Biotechnol."},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Liu, G., Tao, J., Lu, J., Jia, G., Zhao, H., Chen, X., Tian, G., Cai, J., Zhang, R., and Wang, J. (2022). Dietary tryptophan supplementation improves antioxidant status and alleviates inflammation, endoplasmic reticulum stress, apoptosis, and pyroptosis in the intestine of piglets after lipopolysaccharide challenge. Antioxidants, 11.","DOI":"10.3390\/antiox11050872"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"1514","DOI":"10.2527\/1997.7561514x","article-title":"Time course of increased plasma cytokines, cortisol, and urea nitrogen in pigs following intraperitoneal injection of lipopolysaccharide","volume":"75","author":"Webel","year":"1997","journal-title":"J. Anim. Sci."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"291","DOI":"10.1016\/j.livsci.2007.06.011","article-title":"Influences of lipopolysaccharide-induced immune challenge on performance and whole-body protein turnover in weanling pigs","volume":"113","author":"Chen","year":"2008","journal-title":"Livest. Sci."}],"container-title":["Animals"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-2615\/15\/9\/1194\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T17:19:45Z","timestamp":1760030385000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-2615\/15\/9\/1194"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,4,23]]},"references-count":34,"journal-issue":{"issue":"9","published-online":{"date-parts":[[2025,5]]}},"alternative-id":["ani15091194"],"URL":"https:\/\/doi.org\/10.3390\/ani15091194","relation":{},"ISSN":["2076-2615"],"issn-type":[{"value":"2076-2615","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,4,23]]}}}