The effects of Thymus capitatus essential oil topical application on milk quality: a systems biology approach

Abstract

Essential oils (EO) are known for their antibacterial and anti-inflammatory properties and can be used as an alternative to reduce the reliance on antimicrobials in dairy cattle. While many studies have explored the beneficial properties of EO in vitro, their effects on milk quality and milk microbiota, when applied directly to the udder skin, remain relatively unknown. This study aimed to investigate the impact of Thymus capitatus EO (TCEO) on milk microbiota, lipidomic profile and inflammatory biomarkers in dairy cows at the end of the lactation period and udder skin microbiota. Sixteen quarters from 12 Holstein cows were selected, and TCEO was topically applied to the udder skin twice a day for seven days. Milk was collected aseptically at days 0, 7, 21, and 28 before morning farm milking. The results showed no significant changes in microbiota composition after the EO treatment. TCEO had a limited impact on the milk lipidome, primarily affecting diacylglycerol components at T21. The treatment did not affect inflammatory biomarkers, milk sensory properties, and quality. Our study demonstrates that applying 10% TCEO on cow's quarters does not significantly alter milk quality or microbiota composition in milk and skin, suggesting its safe use in dairy cows.