Case Study: Intrauterine infusion of oregano essential oils leads to carvacrol in milk of dairy cows

Abstract

ABSTRACT Objective Our objective was to quantify carvacrol (5-isopropyl-2-methylphenol) in milk after prophylactic intrauterine administration of a natural oregano essential oil product in primiparous lactating Holstein cows under an organic management setting. Materials and Methods A single group of 5 Holstein cows was selected from a certified organic herd. A composite milk sample was collected from each cow as the baseline (0 h). All cows were treated 3 times every other day with an intrauterine solution containing 3.75 mL of natural oregano essential oils (NOEO) diluted in 117 mL of distilled water. Milk sampling schemes were (1) 5 cows sampled at 6, 12, 24, and 48 h after the first NOEO treatment and (2) 2 cows sampled at 6, 12, 24, and 48 h after the third NOEO administration. Carvacrol concentrations were determined using gas chromatograph mass spectrometry. Results and Discussion Carvacrol was detected in the samples collected after NOEO treatment. The highest concentration of carvacrol was at 6 h after the first NOEO treatment (mean ± SD; 0.217 ± 0.159 mg/kg). Most samples were below the limit of quantification after 48 h of the first treatment. Carvacrol reached the mammary alveoli after intrauterine administration of NOEO, with a considerable reduction of concentrations after 48 h of treatment completion. Implications and Applications Carvacrol, the main active ingredient of oregano essential oils, can reach different tissues after local application. This opens research opportunities to investigate the effects of carvacrol on milk quality and flavor, as well as the potential benefits of carvacrol as a antimicrobial and anti-inflammatory agent in the mammary gland and other tissues. Additionally, as we demonstrated the presence of carvacrol in unprocessed milk, the effects of this compound on consumers should be further investigated in relationship to potential health effects.