{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,19]],"date-time":"2026-02-19T03:53:44Z","timestamp":1771473224002,"version":"3.50.1"},"reference-count":32,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2023,4,4]],"date-time":"2023-04-04T00:00:00Z","timestamp":1680566400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100007917","name":"United States Department of Agriculture, Agricultural Research Service (USDA-ARS) as part of National Program 101, Food Animal Production","doi-asserted-by":"publisher","award":["5042-32630-003-00D"],"award-info":[{"award-number":["5042-32630-003-00D"]}],"id":[{"id":"10.13039\/100007917","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Veterinary Sciences"],"abstract":"<jats:p>The isoflavone biochanin A was previously shown to promote weight gain in growing steers by selectively inhibiting rumen bacteria-like growth-promoting feed antibiotics. The hypothesis that biochanin A inhibited the action of drug efflux pumps was tested by enumerating tetracycline-insensitive bacteria from steers in a subacute rumen acidosis (SARA) challenge. Steers (n = 3\/group) treatment groups were forage only, SARA control, SARA with monensin (0.2 g d\u22121), and SARA with biochanin A (6.0 g d\u22121). As the steers were stepped up from the forage-only basal diet to 70% cracked corn, the number of rumen bacteria enumerated on two tetracycline-containing media types (nutrient glucose agar and tetracycline, and bile esculin azide and tetracycline) increased (p &lt; 0.05) from as little as 1.7(105) to as great as 6.7(106) cfu mL\u22121 on the nutrient glucose agar in the SARA and monensin control groups. The biochanin A group maintained the same number of tetracycline-insensitive bacteria as the forage-only controls (p &gt; 0.05). The effects were similar to the more selective media type, but the differences were smaller. These results support the hypothesis that biochanin A inhibits the activity of drug efflux pumps in vivo.<\/jats:p>","DOI":"10.3390\/vetsci10040273","type":"journal-article","created":{"date-parts":[[2023,4,4]],"date-time":"2023-04-04T04:52:14Z","timestamp":1680583934000},"page":"273","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Reduction in Rumen Tetracycline-Insensitive Bacteria during a Grain Challenge Using the Isoflavone Biochanin A"],"prefix":"10.3390","volume":"10","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8868-9169","authenticated-orcid":false,"given":"Michael D.","family":"Flythe","sequence":"first","affiliation":[{"name":"Forage-Animal Production Research Unit, Agricultural Research Service, United States Department of Agriculture, Lexington, KY 40546, USA"},{"name":"Department of Animal & Food Sciences, University of Kentucky, Lexington, KY 40546, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2269-351X","authenticated-orcid":false,"given":"Brittany E.","family":"Davis","sequence":"additional","affiliation":[{"name":"Forage-Animal Production Research Unit, Agricultural Research Service, United States Department of Agriculture, Lexington, KY 40546, USA"},{"name":"Department of Animal & Food Sciences, University of Kentucky, Lexington, KY 40546, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Isabelle A.","family":"Kagan","sequence":"additional","affiliation":[{"name":"Forage-Animal Production Research Unit, Agricultural Research Service, United States Department of Agriculture, Lexington, KY 40546, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2023,4,4]]},"reference":[{"key":"ref_1","first-page":"43","article-title":"Ionophores: Their use as ruminant growth promotants and impact on food safety","volume":"4","author":"Callaway","year":"2003","journal-title":"Curr. 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