Non-Antibiotic Alternatives for Bovine Mastitis Therapy

Project Overview

Project Type: Research and Education
Funds awarded in 2012: $199,912.00
Projected End Date: 12/31/2016
Region: North Central
State: Michigan
Project Coordinator:
Dr. Bo Norby
Michigan State University

Annual Reports

Information Products


  • Animal Products: dairy


  • Animal Production: herbal medicines
  • Education and Training: focus group, on-farm/ranch research
  • Production Systems: organic agriculture


    This project aims to develop intra-mammary, non-antibiotic alternatives to treating mastitis in dairy cows raised under organic and conventional production methods.  In 2013, we determined the minimum inhibitory concentrations (MICs) of Manuka honey for E. coli, Staphylococcus and  Streptococcus isolated from cows with clinical mastitis.  The MICs obtained with Manuka honey were very likely too high to be able to achieve needed concentrations of honey in the quarters of cows with clinical mastitis.  Hence, we redirected our efforts to involve essential oils from plants that have been shown to have very good antibacterial properties.  The tested essential oils had very good antibacterial properties against pathogens isolated form mammary glands of cows with clinical mastitis.  Based on literature/web searches that provided information that essential oils in in vitro and in vivo are very tissue irritant and caused up to a 100-fold increase in somatic cell counts and bloody milk.  Hence, we terminated attempts to assess the safety of intra-mammary infusions of essential oils.


    Mastitis is the most common health condition requiring management on both conventional and organic dairy farms (APHIS, 2008; Ruegg, 2009; Werner et al., 2010).  The cost of each case of mastitis on a dairy averages $155.08 per each episode (Cha et al., 2011) and is estimated to cost the entire US Dairy industry $1.7 – 2 billion each year (Jones and Bailey, 2009).  Vaccinations to reduce the occurrence and/or severity of mastitis, adequate hygiene throughout milking procedures and sanitation in cow housing are effective control methods common to both organic and conventional dairy farms (Fluckey et al., 2009;Ruegg, 2009;USDA, 2008c).  Although conventional dairies rely on antibiotics to prevent new cases of mastitis during the cow’s non-lactating (dry) period and to treat clinical cases of mastitis during lactation (AHPIS, 2008; Werner et al., 2010), antibiotics are not allowed for use in organic dairies under the US National Organic Program (USDA, 2008c;Ruegg, 2009; Werner et al., 2010).  Both organic and conventional dairy producers would benefit from the development of new non-antimicrobial alternatives to bacterial infections in livestock.  These reasons are based on the intense scrutiny of antimicrobial drug use in animal agriculture because of antimicrobial resistance issues, a decrease in market incentives for developing new antimicrobial drugs, and the growing antibiotic-free segment of the dairy industry.

    Alternative mastitis treatments are of importance to improve the sustainability of organic dairy farmers and conventional dairy farmers who are committed to reducing their use of antimicrobial drugs.  Although several guidelines for judicious and prudent use of antimicrobial drugs are available to conventional dairy farmers, there are few documented safe and efficacious alternative treatment options.  Additionally, if there is risk to human health from use of antimicrobial drugs and antimicrobial resistance, the environment and society as a whole will benefit from the availability of non-antimicrobial alternatives for treatment of mastitis.

    Project objectives:

    The objectives of this project are to:

    To determine the minimum inhibitory concentration (MIC) of Manuka honey and guava leaf extract to bacteria commonly associated with bovine mastitis. 

    To establish in-animal safety of candidate formulations and in-milk inhibition metabolites residue depletion

    To determine cure rate of mild to moderate clinical mastitis in dairy cows using candidate formulations

    Work towards completing Objective 1 was performed during 2012-2015.  The first objective of this NCR-SARE project was to assess the in-vitro effect of Manuka Honey and Guava Extract to inhibit the growth of common mastitis pathogens isolated from dairy cows with clinical mastitis.  To accomplish that goal, we proposed to determine the minimum inhibitory concentrations (MIC) of Manuka Honey and Guava Extract for bacteria causing clinical mastitis in dairy cows.  We were not able to identify a source of Guava extract that was consistent in quality and quantity.   The MICs obtained for Manuka honey ~6-8% (weight/volume) are likely so high that we would not be able to obtain high enough concentrations of the honey in the udder of dairy cows to reach the MIC  needed.

    To compensate for the loss of Guava extract and Manuka honey as viable options for treatment of mastitis, we identified several essential oils that appeared to have much lower MICs than Manuka honey.  These oils include: oregano oil, two constituents of oregano oil; carvacrol and thymol, and trans-cinnamaldehyde.

    In 2015, we finished work to determined the MICs to the following essential oils: oregano oil, carvacrol, thymol and trans-cinnamaldehyde.

    Based on literature/web searches that provided information that essential oils in in vitro and in vivo are very tissue irritant and caused up to a 100-fold increase in somatic cell counts and bloody milk.  Hence, we had to abandon the safety studies of mammary infusion of essential oils into the quarters of lactating cows.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.