Flythe Michael D, Davis Brittany E, Kagan Isabelle A
Forage-Animal Production Research Unit, Agricultural Research Service, United States Department of Agriculture, Lexington, KY 40546, USA.
Department of Animal & Food Sciences, University of Kentucky, Lexington, KY 40546, USA.
Vet Sci. 2023 Apr 4;10(4):273. doi: 10.3390/vetsci10040273.
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 ( = 3/group) treatment groups were forage only, SARA control, SARA with monensin (0.2 g d), and SARA with biochanin A (6.0 g d). 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 ( < 0.05) from as little as 1.7(10) to as great as 6.7(10) cfu mL 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 ( > 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.
异黄酮生物活性成分A先前已被证明，通过选择性抑制瘤胃细菌样促生长饲料抗生素，可促进生长中的阉牛体重增加。通过在亚急性瘤胃酸中毒（SARA）挑战中对阉牛体内耐四环素细菌进行计数，验证了生物活性成分A抑制药物外排泵作用的假说。阉牛（每组 = 3头）治疗组分别为仅饲喂草料组、SARA对照组、添加莫能菌素（0.2 g/天）的SARA组和添加生物活性成分A（6.0 g/天）的SARA组。随着阉牛从仅饲喂草料的基础日粮逐步过渡到70%的破碎玉米日粮，在两种含四环素的培养基类型（营养葡萄糖琼脂和四环素，以及胆汁七叶苷叠氮化物和四环素）上计数的瘤胃细菌数量在SARA组和莫能菌素对照组的营养葡萄糖琼脂上从低至1.7×10⁶增加到高达6.7×10⁶ cfu/mL（P < 0.05）。生物活性成分A组的耐四环素细菌数量与仅饲喂草料的对照组相同（P > 0.05）。这些影响与选择性更强的培养基类型相似，但差异较小。这些结果支持了生物活性成分A在体内抑制药物外排泵活性的假说。
