Edwards Joan E, Bequette Brian J, McKain Nest, McEwan Neil R, Wallace R John
Rowett Research Institute, Greenburn Road, Bucksburn, Aberdeen AB21 9SB, UK.
Br J Nutr. 2005 Jul;94(1):64-70. doi: 10.1079/bjn20051444.
Flavomycin is an antibiotic that promotes growth in ruminant and non-ruminant livestock. The aim of this study was to determine the mechanism of action of flavomycin in sheep by measuring microbial numbers, microbial metabolism and gut tissue protein turnover at different sites in the digestive tract. Two weight-matched groups (n 5) of male castrate lambs (30 kg) received 800 g grass cubes/d for 6 weeks, with one group receiving 20 mg/d flavomycin during the last 2 weeks. Samples of digesta and gut tissue segments were obtained immediately post mortem, 90 min after a flood-dose of [ring-D5]phenylalanine. Viable bacterial counts and volatile fatty acid concentrations were highest in ruminal digesta, followed by the colon and caecum, then the duodenum and ileum. The only effect of flavomycin was an increased bacterial count in the rumen (3.5 v. 1.2 x 10(9) per g; P=0.04). Acetate was proportionally greater and propionate and butyrate were lower in the caecum and colon than the rumen. Flavomycin had no effect on volatile fatty acid proportions or ammonia concentrations. Bacteria growing on peptides as sole C source were not affected by flavomycin. Proteolytic, peptidolytic and amino acid deamination activities were similar in the rumen, caecum and colon; they tended to be lower in animals receiving flavomycin. Protein turnover in ruminal wall and duodenal tissues, measured by a flood-dose technique, decreased with flavomycin (P=0.075 and 0.027, respectively). Thus, flavomycin differs from ionophores in its mode of action. It may influence protein metabolism of both digesta and tissue throughout the ruminant digestive tract.
黄霉素是一种可促进反刍动物和非反刍动物生长的抗生素。本研究旨在通过测量消化道不同部位的微生物数量、微生物代谢和肠道组织蛋白质周转情况，来确定黄霉素对绵羊的作用机制。两组体重匹配的去势雄性羔羊（每组n = 5，体重30千克），连续6周每天饲喂800克草块，其中一组在最后2周每天添加20毫克黄霉素。在给予大剂量[环-D5]苯丙氨酸90分钟后立即宰杀动物，采集消化物和肠道组织样本。瘤胃消化物中的活菌计数和挥发性脂肪酸浓度最高，其次是结肠和盲肠，然后是十二指肠和回肠。黄霉素的唯一作用是使瘤胃细菌数量增加（每克分别为3.5×10⁹和1.2×10⁹；P = 0.04）。盲肠和结肠中乙酸比例相对较高，丙酸和丁酸比例低于瘤胃。黄霉素对挥发性脂肪酸比例或氨浓度没有影响。以肽作为唯一碳源生长的细菌不受黄霉素影响。瘤胃、盲肠和结肠中的蛋白水解、肽水解和氨基酸脱氨活性相似；接受黄霉素的动物中这些活性往往较低。通过大剂量技术测量，瘤胃壁和十二指肠组织中的蛋白质周转因黄霉素而降低（分别为P = 0.075和0.027）。因此，黄霉素的作用方式与离子载体不同。它可能会影响反刍动物整个消化道中消化物和组织的蛋白质代谢。
