{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T16:54:06Z","timestamp":1785430446827,"version":"3.56.0"},"reference-count":40,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2026,6,18]],"date-time":"2026-06-18T00:00:00Z","timestamp":1781740800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Shanghai Agriculture Applied Technology Development Program","award":["G20190301"],"award-info":[{"award-number":["G20190301"]}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["32100033"],"award-info":[{"award-number":["32100033"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"award":["32100033"],"award-info":[{"award-number":["32100033"]}],"id":[{"id":"https:\/\/ror.org\/01h0zpd94","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Animals"],"abstract":"<jats:p>Copper supplements are prominent antibiotic alternatives in livestock production, but their excessive use poses environmental risks, necessitating safer substitutes. Potassium diformate (KDF), an organic acid salt, has shown potential as a feed additive, yet its effectiveness in copper-unsupplemented diets remains unclear. This study compared the effects of copper glycinate (Cu_Gly) and KDF on weaned piglets fed a copper-unsupplemented basal diet. Forty-five Meishan piglets were allocated to a control group (basal diet), a Cu_Gly group (basal diet + 60 mg\/kg Cu_Gly), or a KDF group (basal diet + 10 g\/kg KDF). The KDF group exhibited a lower feed conversion ratio (FCR) than the control group. Although no significant differences in average daily gain were observed, KDF supplementation significantly enhanced immune function by increasing plasma IgG and decreasing IgM, IL-6, and IL-1 levels compared to the control. 16S rRNA sequencing analysis revealed that the Control group was enriched with pathogenic genera (Staphylococcus, Escherichia-Shigella, Brevibacterium) in the ileum and cecum. Cu_Gly supplementation enriched Bacillus, Longispora, and Terrisporobacterin the ileum, while KDF increased the abundance of beneficial taxa (TM7, Nesterenkoniain the ileum; Lachnospiraceae_UCG-007 in the cecum). Correlation analysis showed that the abundances of Escherichia-Shigella and Staphylococcus were negatively correlated with IgG but positively correlated with IgM and IL-6. Cecal Lachnospiraceae_UCG-007 (enriched in the KDF group) was negatively correlated with IL-1. In summary, KDF improved feed efficiency and demonstrates superior immunomodulatory effects compared to Cu_Gly. The enrichment of bacteria linked to metal resistance in the Cu_Gly group suggested a potential drawback not associated with KDF. Therefore, KDF represented a viable and sustainable alternative to copper supplements, offering a combination of improved gut health, enhanced immunity, and a reduced environmental risk profile.<\/jats:p>","DOI":"10.3390\/ani16121889","type":"journal-article","created":{"date-parts":[[2026,6,18]],"date-time":"2026-06-18T08:59:38Z","timestamp":1781773178000},"page":"1889","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Comparative Effects of Copper Glycinate and Potassium Diformate on Immunity and Gut Microbiota of Pigs\u2014Potential Analysis of Potassium Diformate as a Copper Additive Substitute"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-4333-3801","authenticated-orcid":false,"given":"Xueyuan","family":"Jiang","sequence":"first","affiliation":[{"name":"Key Laboratory of Livestock and Poultry Resources (Pig) Evaluation and Utilization of Ministry of Agriculture and Rural Affairs, Shanghai Engineering Research Center of Breeding Pig, Institute of Animal Science and Veterinary Medicine, Shanghai Academy of Agricultural Sciences, Shanghai 201106, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hulong","family":"Lei","sequence":"additional","affiliation":[{"name":"Key Laboratory of Livestock and Poultry Resources (Pig) Evaluation and Utilization of Ministry of Agriculture and Rural Affairs, Shanghai Engineering Research Center of Breeding Pig, Institute of Animal Science and Veterinary Medicine, Shanghai Academy of Agricultural Sciences, Shanghai 201106, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuan","family":"Mei","sequence":"additional","affiliation":[{"name":"Key Laboratory of Livestock and Poultry Resources (Pig) Evaluation and Utilization of Ministry of Agriculture and Rural Affairs, Shanghai Engineering Research Center of Breeding Pig, Institute of Animal Science and Veterinary Medicine, Shanghai Academy of Agricultural Sciences, Shanghai 201106, China"},{"name":"College of Animal Science &Technology, Nanjing Agricultural University, Nanjing 210095, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Peng","family":"Jia","sequence":"additional","affiliation":[{"name":"Key Laboratory of Livestock and Poultry Resources (Pig) Evaluation and Utilization of Ministry of Agriculture and Rural Affairs, Shanghai Engineering Research Center of Breeding Pig, Institute of Animal Science and Veterinary Medicine, Shanghai Academy of Agricultural Sciences, Shanghai 201106, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Wen","family":"Yao","sequence":"additional","affiliation":[{"name":"College of Animal Science &Technology, Nanjing Agricultural University, Nanjing 210095, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dong","family":"Xia","sequence":"additional","affiliation":[{"name":"Key Laboratory of Livestock and Poultry Resources (Pig) Evaluation and Utilization of Ministry of Agriculture and Rural Affairs, Shanghai Engineering Research Center of Breeding Pig, Institute of Animal Science and Veterinary Medicine, Shanghai Academy of Agricultural Sciences, Shanghai 201106, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0849-1572","authenticated-orcid":false,"given":"Naisheng","family":"Lu","sequence":"additional","affiliation":[{"name":"Key Laboratory of Livestock and Poultry Resources (Pig) Evaluation and Utilization of Ministry of Agriculture and Rural Affairs, Shanghai Engineering Research Center of Breeding Pig, Institute of Animal Science and Veterinary Medicine, Shanghai Academy of Agricultural Sciences, Shanghai 201106, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,6,18]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"313","DOI":"10.1038\/nri2515","article-title":"The gut microbiota shapes intestinal immune responses during health and disease","volume":"9","author":"Round","year":"2009","journal-title":"Nat. Rev. Immunol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"28","DOI":"10.1186\/s40168-015-0091-8","article-title":"Diet shapes the gut microbiome of pigs during nursing and weaning","volume":"3","author":"Frese","year":"2015","journal-title":"Microbiome"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"54","DOI":"10.1186\/s40104-018-0269-6","article-title":"The dynamics of the piglet gut microbiome during the weaning transition in association with health and nutrition","volume":"9","author":"Guevarra","year":"2018","journal-title":"J. Anim. Sci. Biotechnol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1503","DOI":"10.2527\/1993.7161503x","article-title":"Effect of galactan on selected microbial populations and pH and volatile fatty acids in the ileum of the weanling pig","volume":"71","author":"Mathew","year":"1993","journal-title":"J. Anim. Sci."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"134","DOI":"10.2527\/jas.53798","article-title":"Meta-analysis of effects of microbial phytase on digestibility and bioavailability of copper and zinc in growing pigs","volume":"90","author":"Bikker","year":"2012","journal-title":"J. Anim. Sci."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"917","DOI":"10.1515\/pjvs-2016-0113","article-title":"Supplementation of pigs diet with zinc and copper as alternative to conventional antimicrobials","volume":"19","author":"Debski","year":"2016","journal-title":"Pol. J. Vet. Sci."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"5447","DOI":"10.2527\/jas2017.1702","article-title":"Copper hydroxychloride improves growth performance and reduces diarrhea frequency of weanling pigs fed a corn\u2013soybean meal diet but does not change apparent total tract digestibility of energy and acid hydrolyzed ether extract","volume":"95","author":"Espinosa","year":"2017","journal-title":"J. Anim. Sci."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"2267","DOI":"10.1128\/AEM.71.5.2267-2277.2005","article-title":"Influence of dietary zinc oxide and copper sulfate on the gastrointestinal ecosystem in newly weaned piglets","volume":"71","author":"Canibe","year":"2005","journal-title":"Appl. Environ. Microbiol."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"184","DOI":"10.1007\/s12011-012-9410-0","article-title":"Effects of copper-loaded chitosan nanoparticles on intestinal microflora and morphology in weaned piglets","volume":"149","author":"Wang","year":"2012","journal-title":"Biol. Trace Elem. Res."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"209","DOI":"10.1007\/s11270-019-4249-z","article-title":"Copper and zinc in rhizosphere soil and toxicity potential in white oats (Avena sativa) grown in soil with long-term pig manure application","volume":"230","author":"Benedet","year":"2019","journal-title":"Water Air Soil Poll."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"54","DOI":"10.1186\/s40104-020-00457-y","article-title":"Optimal dietary copper requirements and relative bioavailability for weaning pigs fed either copper proteinate or tribasic copper chloride","volume":"11","author":"Lin","year":"2020","journal-title":"J. Anim. Sci. Biotechnol."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1875","DOI":"10.2527\/2000.7871875x","article-title":"Effect of dietary formates on growth performance, carcass traits, sensory quality, intestinal microflora, and stomach alterations in growing-finishing pigs","volume":"78","author":"Granli","year":"2000","journal-title":"J. Anim. Sci."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"169","DOI":"10.1016\/j.livsci.2007.07.007","article-title":"Organic acids in diets for entire male pigs: Effect on skatole level, microbiota in digesta, and growth performance","volume":"115","author":"Kjos","year":"2008","journal-title":"Livest. Sci."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"85","DOI":"10.1016\/j.livsci.2014.12.003","article-title":"Potassium diformate influences gene expression of GH\/IGF-I axis and glucose homeostasis in weaning piglets","volume":"172","author":"Zhou","year":"2015","journal-title":"Livest. Sci."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"131","DOI":"10.1016\/S0377-8401(02)00069-X","article-title":"Establishment and application of an in vitro methodology to study the effects of organic acids on coliform and lactic acid bacteria in the proximal part of the gastrointestinal tract of piglets","volume":"99","author":"Knarreborg","year":"2002","journal-title":"Anim. Feed Sci. Techol."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"2123","DOI":"10.2527\/2001.7982123x","article-title":"Effect of K-diformate in starter diets on acidity, microbiota, and the amount of organic acids in the digestive tract of piglets, and on gastric alterations","volume":"79","author":"Canibe","year":"2001","journal-title":"J. Anim. Sci."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"84","DOI":"10.1111\/j.1439-0396.2005.00537.x","article-title":"Investigations on prophylactic effects of coarse feed structure and\/or potassium diformate on the microflora in the digestive tract of weaned piglets experimentally infected with Salmonella Derby","volume":"89","author":"Papenbrock","year":"2005","journal-title":"J. Anim. Physiol. Anim. Nutr."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"350","DOI":"10.1111\/j.1439-0396.2008.00894.x","article-title":"Effects of dietary additives (potassium diformate\/organic acids) as well as influences of grinding intensity (coarse\/fine) of diets for weaned piglets experimentally infected with Salmonella Derby or Escherichia coli","volume":"93","author":"Taube","year":"2009","journal-title":"J. Anim. Physiol. Anim. Nutr."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"102","DOI":"10.1046\/j.1439-0396.2000.00288.x","article-title":"Effects of potassium diformate (Formi\u00ae LHS) in combination with different grains and energy densities in the feed on growth performance of weaned piglets","volume":"84","author":"Paulicks","year":"2000","journal-title":"J. Anim. Physiol. Anim. Nutr."},{"key":"ref_20","first-page":"87","article-title":"Effect of potassium diformate in combination with different amounts and sources of excessive dietary copper on production performance in weaning piglets","volume":"54","author":"Windisch","year":"2001","journal-title":"Arch. Anim. Nutr."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"321","DOI":"10.1016\/j.aninu.2021.10.007","article-title":"Different copper sources and levels affect growth performance, copper content, carcass characteristics, intestinal microorganism and metabolism of finishing pigs","volume":"8","author":"Wen","year":"2022","journal-title":"Anim. Nutr."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1062","DOI":"10.2527\/2004.8241062x","article-title":"Copper proteinate in weanling pig diets for enhancing growth performance and reducing fecal copper excretion compared with copper sulfate","volume":"82","author":"Veum","year":"2004","journal-title":"J. Anim. Sci."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"757","DOI":"10.5713\/ajas.2010.80437","article-title":"Effect of dietary copper sources (cupric sulfate and cupric methionate) and concentrations on performance and fecal characteristics in growing pigs","volume":"23","author":"Huang","year":"2010","journal-title":"Asian-Australas. J. Anim. Sci."},{"key":"ref_24","unstructured":"(2018). The Laboratory Animal-Guideline for Ethical Review of Animal Welfare (Standard No. GB\/T 35892-2018)."},{"key":"ref_25","first-page":"123","article-title":"The use of organic acids in animal nutrition, with special focus on dietary potassium diformate under European and Austral-Asian conditions","volume":"18","author":"Mellor","year":"2011","journal-title":"Recent Adv. Anim. Nutr. Aust."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"45","DOI":"10.1186\/s40104-015-0042-z","article-title":"A review of the effects of dietary organic acids fed to swine","volume":"6","author":"Suiryanrayna","year":"2015","journal-title":"J. Anim. Sci. Biotechnol."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Rathnayake, D., Mun, H.S., Dilawar, M.A., Baek, K.S., and Yang, C.J. (2021). Time for a paradigm shift in animal nutrition metabolic pathway: Dietary inclusion of organic acids on the production parameters, nutrient digestibility, and meat quality traits of swine and broilers. Life, 11.","DOI":"10.20944\/preprints202104.0085.v1"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"623","DOI":"10.1016\/S0271-5317(02)00371-8","article-title":"Phytase and acetic acid supplementation in the diet of early weaned piglets: Effect on performance and apparent nutrient digestibility","volume":"22","author":"Valencia","year":"2002","journal-title":"Nutr. Res."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"113","DOI":"10.1016\/S0301-6226(00)00179-2","article-title":"The effects of microbial phytase, organic acids and their interaction in diets for growing pigs","volume":"67","author":"Jongbloed","year":"2000","journal-title":"Livest. Prod. Sci."},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"F\u00e9vrier, C., Gotterbarm, G., Jaguelin-Peyraud, Y., Lebreton, Y., Legouevec, F., and Aumaitre, A. (2001). Effects of adding potassium diformate and phytase excess for weaned piglets. Digestive Physiology of Pigs, Swedish University of Agricultural Sciences.","DOI":"10.1079\/9780851995175.0192"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"439","DOI":"10.1016\/S0739-7240(98)80001-5","article-title":"Cytokines as markers for infections and their effect on growth performance and well-being in the pig","volume":"15","author":"Fossum","year":"1998","journal-title":"Domest. Anim. Endocrinol."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"93","DOI":"10.5713\/ajas.2013.13411","article-title":"Comparison of single and blend acidifiers as alternative to antibiotics on growth performance, fecal microflora, and humoral immunity in weaned piglets","volume":"27","author":"Ahmed","year":"2014","journal-title":"Asian-Australas. J. Anim. Sci."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"144","DOI":"10.1016\/j.aninu.2021.06.009","article-title":"Dietary ferulic acid and vanillic acid on inflammation, gut barrier function and growth performance in lipopolysaccharide-challenged piglets","volume":"8","author":"Hu","year":"2022","journal-title":"Anim. Nutr."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"S41","DOI":"10.1016\/j.jaci.2009.09.046","article-title":"Structure and function of immunoglobulins","volume":"125","author":"Schroeder","year":"2010","journal-title":"J. Allergy Clin. Immunol."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"139","DOI":"10.1016\/j.domaniend.2009.04.004","article-title":"Temporal pattern and effect of sex on lipopolysaccharide-induced stress hormone and cytokine response in pigs","volume":"37","author":"Williams","year":"2009","journal-title":"Domest. Anim. Endocrinol."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"681","DOI":"10.1021\/acscombsci.8b00088","article-title":"Combating a master manipulator: Staphylococcus aureus immunomodulatory molecules as targets for combinatorial drug discovery","volume":"20","author":"Rakesh","year":"2018","journal-title":"Acs Comb. Sci."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"3341","DOI":"10.1007\/s12011-022-03434-w","article-title":"Selenium mitigates ammonia-induced neurotoxicity by suppressing apoptosis, Immune Imbalance, and gut microbiota-driven metabolic disturbance in fattening pigs","volume":"201","author":"Li","year":"2022","journal-title":"Biol. Trace Elem. Res."},{"key":"ref_38","first-page":"12","article-title":"Effect of graphene and graphene oxide on antibiotic resistance genes during copper-contained swine manure anaerobic digestion","volume":"1","author":"Zhang","year":"2022","journal-title":"Environ. Sci. Pollut. Res."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"124403","DOI":"10.1016\/j.biortech.2020.124403","article-title":"The fate of antibiotic resistance genes in cow manure composting: Shaped by temperature-controlled composting stages","volume":"320","author":"Sardar","year":"2021","journal-title":"Bioresour. Technol."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"35","DOI":"10.1186\/s40793-015-0021-1","article-title":"Genome sequences of copper resistant and sensitive Enterococcus faecalis strains isolated from copper-fed pigs in Denmark","volume":"10","author":"Zhang","year":"2015","journal-title":"Stand. Genom. Sci."}],"container-title":["Animals"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-2615\/16\/12\/1889\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,6,18]],"date-time":"2026-06-18T09:30:40Z","timestamp":1781775040000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-2615\/16\/12\/1889"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,6,18]]},"references-count":40,"journal-issue":{"issue":"12","published-online":{"date-parts":[[2026,6]]}},"alternative-id":["ani16121889"],"URL":"https:\/\/doi.org\/10.3390\/ani16121889","relation":{},"ISSN":["2076-2615"],"issn-type":[{"value":"2076-2615","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,6,18]]}}}