Adopting a New Culling Strategy to Reduce Johne’s Disease and Improve Economic Sustainability on Dairy Farms

Progress report for ONE22-416

Project Type: Partnership
Funds awarded in 2022: $25,950.00
Projected End Date: 07/31/2024
Grant Recipient: University of Vermont Extension
Region: Northeast
State: Vermont
Project Leader:
Whitney Hull
University of Vermont Extension
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Project Information

Project Objectives:
  1. This project seeks to determine whether partner farms would be willing to use early lactation culling as a management strategy to control Johne’s disease within their herd. We will use a participatory approach to understand the motivations behind decision making in this context.
  2. This project seeks to understand the role of providing certain information to support the early lactation culling decisions of partner farms. We will provide testing and a partial budget to support decision making.
  3. This project seeks to share knowledge with other dairy producers and recruit them to adopt this approach to Johne’s disease management on their own farms. In order to help additional farms implement these management strategies, we will provide a framework to support their decision making.




Johne’s disease is an infectious disease common within the dairy industry caused by the bacterium Mycobacterium avium subspecies paratuberculosis (MAP). Johne’s disease is a significant challenge for both animals and producers as it leads to milk production loss, premature culling, and reduced slaughter values. It has been estimated that over 60% of the nation's dairy herds are infected with Johne's disease at some level (Barkema, 2018). The economic impacts of Johne's disease within the dairy industry in the United States are estimated to be approximately $200 million annually (Rasmussen, 2021). It can be difficult to truly assess the cost of Johne’s disease on a per cow or herd level basis since the costs of the disease are indirect in the form of lost milk production, poor reproduction, and premature culling from the herd. However, a recent study estimated that the per cow revenue loss is $33 USD per year for herds infected with Johne’s disease (Rasmussen, 2021). This seems like a relatively small and innocuous number, but these losses equate to roughly 1% of a herd’s total milk revenue per year. In an industry that operates on increasingly small margins, the ability to increase farm revenue by even 1% can have a significant impact on a farm’s overall economic sustainability.

Johne’s disease can be difficult to diagnose, as it is only when an animal starts to shed a high enough level of MAP bacteria that infection can be accurately detected by diagnostic tests. Testing and culling animals that test positive has been used as a method for reducing the spread of Johne’s disease within a herd. This can be a problematic control method due to the potential for error in test results. Additionally, most farms find it cost-prohibitive to routinely test animals. While much of the research has been focused on reducing the spread of Johne’s disease through testing and other management improvements, there is a lack of research that looks at how milk production is impacted by the disease. A promising approach to understanding how Johne’s disease affects milk production was published in 2008 by Smith et al., but the applications of their findings have yet to be fully explored. By using milk production data already collected by the farm, our study will look at decision making regarding culling animals within the first 90 days of lactation. In partnership with local dairy farms, we propose to use milk production data to identify cows for removal from the herd based on poor performance, which may be an indicator of infection with Johne’s disease. In any case, these animals may have a negative economic impact on the farm. In order to support the farm’s decision-making process surrounding culling animals in early lactation, we will test low producing animals for Johne’s disease. We will also analyze the economics of the culling decisions.

In keeping with the desired outcomes of SARE, this project aims to improve animal health and economic sustainability of our partner farms, which represent a diverse spectrum of dairy production styles, including conventional and organic farms. Our proposed outcome would show that culling low producing animals in the early stages of their lactation is both an effective means to control Johne’s disease within a herd, as well as have a positive economic benefit to overall farm profitability. We hope to encourage other farms to adopt our management practices surrounding culling, so we also seek to understand how different farmers are motivated to change their behaviors. Successful adoption of the new culling strategy by partner farms would suggest our results will be widely applicable to all types of dairy farms.

















Click linked name(s) to expand/collapse or show everyone's info
  • Grady Ballard - Producer
  • Tristan Butler - Producer
  • Rebecca Howrigan - Producer
  • Mark Magnan - Producer
  • Stephen Wadsworth - Technical Advisor (Educator)


Materials and methods:

Objective 1:

Step 1: Recruit additional partner farms. This project is designed as an on-farm participatory research project. There will be between 4 and 10 farms. Four farms have committed to this project so far, and additional farms will be recruited with the assistance of local veterinarians. We will enroll up to 10 farms of varying sizes, including both conventional and organic herds.

This first objective has been completed. Eight farms, including organic and conventional dairies, have been recruited for this study. Local veterinarians were used to recruit partner farms.

Step 2: Evaluate partner farm perceptions surrounding Johne’s disease and culling decisions in early lactation. We will interview partner farms using the attached interview protocol to understand their current perceptions of Johne’s disease presence on their farm, as well as management strategies related to disease management. In addition, we will ask about their current processes for culling animals and how likely they would be to adopt a new management strategy related to culling in early lactation. The data analysis will involve coding of themes so we can summarize motivations for culling decisions and understand how best to design messaging to encourage on-farm adoption of our proposed culling strategies. This approach is consistent with the theory of planned behavior, which looks at the likelihood for a person to engage in a behavior.

The second objective has been completed using the interview protocol attached. Farmer responses have been given a number in order to maintain anonymity. A variety of responses related to motivations surrounding behavior were recorded. A slightly modified version of these survey questions will be given again at the end of the study to determine whether any changes related to culling behavior and disease management were implemented, as well as knowledge gained throughout the study. The survey results will then be used to help shape our outreach.

Step 3: Determine presence of Johne’s disease within herds. Each herd enrolled in the study will receive a herd-level screening test for Johne’s disease to identify whether there is a detectable presence of the disease within the herd. Pooled fecal samples from individual cows or environmental samples from a minimum of 6 sites on the farm will be tested for the Johne’s organism using a molecular PCR test performed at a veterinary diagnostic laboratory. The most cost-effective testing strategy will be selected for each farm. The test results will serve as a baseline estimate of the level of shedding in the herd and are provided as a benefit for farms participating in the project. Knowing the baseline will be important since we expect that culling will reduce disease presence on these farms over time.

This step has been completed. All farms have had an environmental fecal culture of six individual locations to determine whether there is a presence of Johne's disease within the herd. Environmental results have been presented to each partner farm.

Step 4: Establish production cut points for considering culling. Before implementing new culling decisions, farms will first need to establish cut points for low production based on their herd’s milk production records. To establish cut points, we will use either monthly DHIA milk test information or daily milk weights, depending on the production records used by the farm. For farms that test monthly, we will use week 4 milk production from the previous 12 months to establish benchmarks for each lactation group. Then we will work with each farm to set the amount below the production benchmarks to use as the cut point. Cut points will be determined by lactation group for 1st lactation, 2nd lactation, and 3rd and greater lactation cows. Cows with production below the cut point will be identified for potential culling by the farm. For herds that record daily milk weights, we will monitor milk production for the first 28 days of lactation. In these herds, the culling decision cut point will be when a cow in 1st lactation has not increased production daily for the first 20 days in milk, or a cow in 2nd or higher lactation has not increased daily production for the first 28 days in milk. Other health events that can contribute to low production, such as mastitis or transition related issues, will be recorded.   

This step has been completed, although it has been modified from our original proposal of establishing production cut points based on herd production records. In analyzing the production data, it became clear that there was not a "one size fits all" approach to applying production cut points to each farm. Instead, we decided to allot tests based on a percentage of calvings expected within a six month period. From there, we have worked with each farm to establish criteria for selecting animals for individual testing. By looking at herd production data for stage of lactation and parity, cows under 100 DIM and deviating more than -10 pounds from their previous monthly production are selected for testing. This method is combined with producer input based on animals that they determined were not producing as expected in the first 100 days of lactation. We felt that this approach was a more realistic expectation for farms that may adopt these management strategies after the study is completed.

Step 5: Decide how information will be used to influence culling decisions. We will seek to understand how farms feel about culling early lactation animals based on production alone. We will work with partner farms to develop a plan for how they will use production data and test results to make a culling decision.

This step is currently in progress. After each round of individual test results come back, an economic analysis is run for each tested animal and these results are presented to the farm. The farm is able to take that information and decide whether they would like to cull the animal based on the data provided, or for that animal to remain in the herd.


Objective 2:

Step 1: Provide testing to farms. Because farms may not be willing to cull a cow in early lactation based on production alone, we will offer a fecal PCR test to determine Johne’s disease status of animals that fell below established cut points. We have budgeted to allow us to test up to 50 animals per herd or a total of 430 cows over the period of the study. The timeframe for testing will be from September through April, to avoid the confounding influence of heat stress as a cause of decreased production.

The individual testing of cows on partner farms is roughly halfway completed. Testing has been completed on three farms, and we expect to complete the remainder of the individual tests by the end of May 2024.

Step 2: Present test results to farms. There are four possible test result outcomes of a fecal PCR test; high-shedder, moderate shedder, low shedder, and negative. Test results will be presented to the partner farms. Farms will use this information according to the plan developed in objective 1.

Test results are presented to farms after each round of testing. Animals with a high-shedder result are recommended for culling from the herd. Animals with a moderate, low, or suspect (very low positive or contamination) are generally recommended to be retested at a later stage of lactation to see if the results have changed. There are instances when an animal my be a low shedder on one test and then negative on a subsequent test due to ingestion of the MAP bacteria that is simply passing through the animal but not truly infecting them with the disease.

Step 3: Develop partial budgets. A partial budget is useful for understanding the economic benefits of implementing a management change and will be developed to assess the economic benefits of culling low production animals within early lactation. We will present a partial budget specific to each partner farm, which shows the economic costs and benefits of implementing our proposed management change, assuming all else remains the same.

Along with the individual test results, each farm receives an economic analysis for each cow tested for Johne's disease. This economic analysis has a series of inputs based on each individual herd's metrics and compares a cow to her herdmates and gives that animal an economic value compared to a replacement animal. This is a supporting piece of information that may help a farm feel more comfortable culling a cow in early lactation if she has a very negative economic value in the herd. This tool has informed a lot of conversations around management with the partner farms.

Step 4: Reevaluate culling strategy. We will work in collaboration with partner farms to evaluate, based on the available information, whether the initially developed culling plan is adequate or whether it needs to be modified. If the budget has not been exhausted in year 1, we would request a no cost extension in order to recruit additional farms and allow for, at a minimum, herd level screening tests for Johne’s disease and limited testing of individual animals.

Based on our results so far, partner farms are willing to cull an animal classified as a "high shedder" in early lactation, but are more resistant to cull moderate or low shedders, even when the economic analysis indicates they should do so.


Objective 3:

Step 1: Present preliminary findings to farmer groups. We will find opportunities to present our preliminary results at 2 or more producer meetings and share our results with the broader dairy farming community. The purpose of these meetings will be to recruit additional producers to adopt this management change on their farms.

We are planning to host farmer focus groups in the spring of 2024 to take a look at the motivations and barriers to management changes related to Johne's disease control. We will use the information collected at these focus groups to inform our further outreach.

Step 2: Recruit additional farms. Other farms that are interested in adopting and implementing management changes based on preliminary results from this partnership study will be enrolled. (This is dependent on the success of the prior objectives with our partner farms.) We will use the framework established in the previous two objectives to implement the proposed management changes with these additional herds. If the budget allows, we will provide the same herd level screening test for Johne’s disease.

Step 3: Provide framework. Create a digital copy of the framework used that will be located online for farms to easily access. This will allow more farms, regardless of location, to be able to adopt the framework on their own farm. We believe this management approach will be applicable across all types of dairies.

Step 4: Evaluation of success. Project leaders will evaluate the satisfaction of participating farmers with this approach to controlling Johne’s disease and enhancing profitability.
























Participation Summary
8 Farmers participating in research

Education & Outreach Activities and Participation Summary

Participation Summary:

Education/outreach description:

We will use a proven outreach approach, which is based on utilizing respected, innovative, and motivated local producers to try new practices and share their results and experiences with other dairy farmers. This in combination with tracking outcomes and a focused outreach plan has resulted in good practice adoption and transfer of knowledge. Our partner farmers are an excellent representation of the overall dairy landscape in Vermont, showcasing a variety of sizes and management styles and representing both organic and conventional styles of dairy farming.

Hull, as a member of the UVM Extension Agricultural Business team, has access to a robust network of farmers, agency staff, service providers, policy makers, and other stakeholders. The team also has a robust outreach infrastructure that reaches hundreds of farms every year through technical assistance, field days, social media, and newsletters. We will target outreach to farmers in several ways. First, we will hold two producer meetings in Franklin and Addison counties to present the final results of this partnership project. UVM Extension’s media team will assist in promoting this research across university channels as well as other outlets such as Across the Fence and local newspapers. The project can be promoted in AgriView, the monthly newspaper put out by the Vermont Agency of Agriculture, Food and Markets, and distributed to all farmers within Vermont. Hull will present project findings to farmer-led organizations, such as the Champlain Valley Farmer Coalition, and producer meetings led by veterinarians, such as the through the Northwest Veterinary Associates.

A similar approach will target service providers, agency staff, veterinarians, and policy makers. Hull also plans to communicate research findings to Extension agents through the New England Extension In-Service meeting. Organic farms will be reached at local grazing field days and conferences. In addition, having worked with over 30 farms to implement management techniques in the last six months, Hull will also promote the results of the research through one-on-one interactions.

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.