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OSCII Activity D.44

Evaluating alternative therapies for the treatment of clinical mastitis on organic dairies

Activity summary

Mastitis is the most frequent and costly health problem for organic and conventional dairy producers. Mastitis has important deleterious impacts on dairy herd productivity, longevity, and profitability because of decreased milk production, decreased reproductive performance, costs associated with treatments, and the increased risk of culling and death of affected animals. Additionally, antibiotic treatments used to treat clinical mastitis (CM) represent a very large proportion of the antibiotics used on Canadian dairies. For their certification, organic dairy herds have to meet specific requirements and the use of conventional antimicrobial treatments is very restricted. In cases of clinical diseases, such as CM, alternative therapies must first be instituted, and conventional antimicrobial treatments must only be used when alternative therapies are not successful. Numerous alternative therapies for bovine mastitis have been the object of anecdotic reports, with some demonstrating promising results. Few, however, have been formally evaluated in randomized clinical trials (RCT), which is the gold-standard for evaluating the effect of medical treatments. For dairy practitioners and extension agents, providing evidence-based advice on alternative therapies is, therefore, a difficult task, since results on the efficacy of these approaches have never been collated as a coherent whole, and most have not even been formally evaluated in a RCT. The general objective of the proposed study is to identify, evaluate, and promulgate an alternative multi-pronged approach for the treatment of CM in dairy cows.

First, a systematic review of the literature will be conducted to identify alternative therapies for CM in dairy cows and to evaluate their effectiveness. Relevant literature will be identified using a combination of database searches and iterative screening of references. Findings from the selected studies will be collated into a coherent whole, explored, and described, and a statistical combination of individual effects (i.e. a meta-analysis) will be carried out if appropriate. Results from this first study will allow the identification of already proven effective therapies and of a few promising therapies for the treatment of CM in dairy cows. Furthermore, results from this study will be synthesized to constitute a reference manuscript on which veterinary practitioners and extension agents will be able to rely to provide evidence-based advice to their organic dairy clients.

Then, following the systematic review, a phase III RCT will be conducted on 30 commercial conventional dairies to scientifically evaluate the effectiveness of a multi-pronged alternative approach for the treatment of grade 1 (abnormal milk without swelling of the quarter nor systemic signs) and 2 (abnormal milk and swelling of the quarter, but no systemic signs) CM. Since a relatively high rate of spontaneous CM resolution is expected (>30%), the effectiveness of the proposed approach will be compared to negative control cows receiving a placebo formulation and to positive control cows receiving an antibiotic formulated for the treatment of CM. According to a cure chart and for welfare reasons, cows that are not responding to the initial treatment will be allowed to receive in second line an antimicrobial treatment. All analyses will be carried out on an “intent-to-treat” basis. Outcomes studied will be clinical cure (resolution of clinical symptoms), bacteriological cure (resolution of the intra-mammary infection based on routine milk bacteriological culture), and milk production following treatment.

The proposed study will allow the elaboration of a first scientifically-informed guide on alternative therapies for the treatment of CM in dairy cows. Furthermore, effectiveness of a novel alternative multi-pronged approach for the treatment of CM will be evaluated. Identifying an efficient multi-pronged alternative approach for the treatment of CM will help enhance animal health and welfare, which are important concerns for organic dairy producers and consumers. Improving the treatment of CM on organic dairies will help mitigate the costs associated with these very common disease events, and organic dairy herd productivity, longevity, and ultimately, profitability will be increased. Finally, identifying an alternative approach to the treatment of CM would result in a substantial reduction of the amount of antimicrobials used on organic and conventional dairies and of the risk of residues in the organic milk supply, which would be an important safeguard to preserve the safety and positive image of organic and conventional dairy products.

Activity researchers

Name Affiliation
Simon Dufour, Activity Co-Leader Université de Montréal
David Francoz, Activity Co-Leader Université de Montréal
Hubert Karreman Penn Dutch Cow Care
François Labelle Valacta Inc.

Pierre Lacasse
Agriculture and Agri-Food Canada
Dairy and Swine Research and Development Centre
Jean-Philippe Roy Université de Montréal
Vincent Wellemans Université de Montréal