Abstract
Nonantibiotic
treatments for mastitis are needed in organic dairy herds.
Plant-derived oils may be useful but efficacy and potential mechanisms
of action of such oils in mastitis therapy have not been well
documented. The objective of the current study was to evaluate the
antibacterial activity of the plant-derived oil components of Phyto-Mast
(Bovinity Health LLC, Narvon, PA), an herbal intramammary product,
against 3 mastitis-causing pathogens: Staphylococcus aureus, Staphylococcus chromogenes, and Streptococcus uberis. Plant-derived oils evaluated were Thymus vulgaris (thyme), Gaultheria procumbens (wintergreen), Glycyrrhiza uralensis (Chinese licorice), Angelica sinensis, and Angelica dahurica.
Broth dilution testing according to standard protocol was performed
using ultrapasteurized whole milk instead of broth. Controls included
milk only (negative control), milk + bacteria (positive control), and
milk + bacteria + penicillin-streptomycin (antibiotic control, at 1 and
5% concentrations). Essential oil of thyme was tested by itself and not
in combination with other oils because of its known antibacterial
activity. The other plant-derived oils were tested alone and in
combination for a total of 15 treatments, each replicated 3 times and
tested at 0.5, 1, 2, and 4% to simulate concentrations potentially
achievable in the milk within the pre-dry-off udder quarter. Thyme oil
at concentrations ≥2% completely inhibited bacterial growth in all
replications. Other plant-derived oils tested alone or in various
combinations were not consistently antibacterial and did not show
typical dose-response effects. Only thyme essential oil had consistent
antibacterial activity against the 3 mastitis-causing organisms tested
in vitro. Further evaluation of physiological effects of thyme oil in
various preparations on mammary tissue is recommended to determine
potential suitability for mastitis therapy.
Key words
- mastitis;
- plant-derived oils;
- alternative to antibiotics;
- organic
Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.
