Flaxseed-enriched diets change milk concentration of the antimicrobial danofloxacin in sheep

Background: Flaxseed is the most common and rich dietary source of lignans and is an acceptable supply of energy for livestock. Flaxseed lignans are precursors of enterolignans, mainly enterolactone and enterodiol, produced by the rumen and intestinal microbiota of mammals and have many important biological properties as phytoestrogens. Potential food-drug interactions involving flaxseed may be relevant for veterinary therapy, and for the quality and safety of milk and dairy products. Our aim was to investigate a potential food-drug interaction involving flaxseed, to explore whether the inclusion of flaxseed in sheep diet affects concentration of the antimicrobial danofloxacin in milk. Results: Increased concentrations of enterodiol and enterolactone were observed in sheep plasma and milk after 2 weeks of flaxseed supplementation (P < 0.05). However, enterolactone and enterodiol conjugates were not detected in milk. Milk danofloxacin pharmacokinetics showed that area under the curve (AUC)(0-24), maximum concentration (C-max) and AUC(0-24) milk-to-plasma ratios were reduced by 25-30% in sheep fed flaxseed-enriched diets (P < 0.05). Our results demonstrate, therefore, that flaxseed-enriched diets reduce the amount of danofloxacin in sheep milk and enrich the milk content of lignan-derivatives. Conclusion: These findings highlight an effect of flaxseed-enriched diets on the concentration of antimicrobials in ruminant's milk, revealing the potential of these modified diets for the control of residues of antimicrobial drugs in milk.