{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,23]],"date-time":"2026-06-23T17:52:41Z","timestamp":1782237161931,"version":"3.54.5"},"reference-count":31,"publisher":"MDPI AG","issue":"13","license":[{"start":{"date-parts":[[2026,6,23]],"date-time":"2026-06-23T00:00:00Z","timestamp":1782172800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Micronutrients"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Animals"],"abstract":"<jats:p>A study was conducted to determine the effects of the level and source of copper (Cu) on Cu concentrations and the mRNA expression of Cu regulatory proteins in the small intestine of pigs. Thirty weanling castrated male pigs, approximately 21 days of age, were stratified by weight and assigned to dietary treatments consisting of control (6.7 mg Cu\/kg from feed ingredients; no supplemental Cu) or 225 mg supplemental Cu from either Cu sulfate (CuSO4) or tribasic Cu chloride (TBCC). Pigs were harvested on days 35 or 36. The soluble Cu and mucosal Cu concentrations in the duodenum, proximal jejunum, and ileum were higher (p &lt; 0.001) in Cu-supplemented pigs versus controls. Duodenal soluble and mucosal Cu concentrations were higher in (p &lt; 0.05) CuSO4 versus TBCC-supplemented pigs. However, proximal jejunum and ileum mucosal Cu were higher (p &lt; 0.05) in TBCC versus CuSO4 pigs. The intestinal copper transporter 1 (CTR1) expression was lower (p &lt; 0.05) in Cu-supplemented pigs compared to control pigs but was not affected by the intestinal section or treatment x section. The duodenal mRNA expression of metallothionein1a (MT1a) was greater (p &lt; 0.05) in Cu-supplemented pigs and was greater in CuSO4 than TBCC-fed pigs. These data demonstrate that both the Cu level and source affect the Cu uptake and mRNA expression of Cu regulatory proteins throughout the small intestine of weanling pigs.<\/jats:p>","DOI":"10.3390\/ani16131940","type":"journal-article","created":{"date-parts":[[2026,6,23]],"date-time":"2026-06-23T17:11:49Z","timestamp":1782234709000},"page":"1940","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Level and Source of Copper Affects Gene Expression of Copper-Regulatory Proteins and Soluble and Mucosal Copper Concentrations in the Small Intestine of Weanling Pigs"],"prefix":"10.3390","volume":"16","author":[{"given":"Robert Scott","family":"Fry","sequence":"first","affiliation":[{"name":"Department of Animal Science, North Carolina State University, Raleigh, NC 27695, USA"},{"name":"Phibro Animal Health Corp., Teaneck, NJ 07666-6712, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Melissa S.","family":"Ashwell","sequence":"additional","affiliation":[{"name":"Department of Animal Science, North Carolina State University, Raleigh, NC 27695, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"William L.","family":"Flowers","sequence":"additional","affiliation":[{"name":"Department of Animal Science, North Carolina State University, Raleigh, NC 27695, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kara R.","family":"Stewart","sequence":"additional","affiliation":[{"name":"Department of Animal Science, North Carolina State University, Raleigh, NC 27695, USA"},{"name":"Smithfield Foods, Rose Hill, NC 28458, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Karen E.","family":"Lloyd","sequence":"additional","affiliation":[{"name":"Department of Animal Science, North Carolina State University, Raleigh, NC 27695, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0927-609X","authenticated-orcid":false,"given":"Jerry W.","family":"Spears","sequence":"additional","affiliation":[{"name":"Department of Animal Science, North Carolina State University, Raleigh, NC 27695, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,6,23]]},"reference":[{"key":"ref_1","unstructured":"National Research Council (2012). 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