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National Johne's Disease Demonstration Herd Project 

Background and Justification

Goal II of the Report of the Ad Hoc Steering Subcommittee of the USAHA Committee on Johne’s Disease (2002) is “to define critical knowledge gaps that influence producer participation and affect Johne’s disease control.”  One objective under this goal is “to develop and validate model strategies for control of Johne’s disease,” stating that “demonstration herds … are critical and of the highest priority to provide the validated management tools to implement a science-based National Johne’s Disease Program.”

The importance of the Johne’s Disease Demonstration Herd Project was affirmed at a meeting with the Veterinary Services Management Team in Ames, IA on May 1, 2003.  This project has a 2003 budget of $1.5 million to USDA-APHIS-VS and states plus additional funding to CEAH for personnel to support this study.

Demonstration Herd Committee Task and Timelines

The designated task of the Demonstration Herd Committee of NJWG is to provide oversight and guidance to National Johne’s Disease Demonstration Herd Project.  Our timeline for producing an initial model for the program is July 1, 2003. Committee members include: Scott Wells-Chair; Ian Gardner, Bill Shulaw, Sue Stehman, Mike Carter, Andy Schwartz, Dave Dargatz, Brian McCluskey and Jason Lombard.

Project Considerations

The feasibility and success of Johne’s control programs on farms is highly dependent on the interrelationships between attitudes, motivation, farm resources (human, facilities and financial), farm goals, management and health priorities, the perceived and real impact of Johne’s on the farm, and clearly defined Johne’s goals. Factors vary with each farm situation requiring a customized approach based on common principles.  While recognizing that Johne’s disease control is more a process than a program, our goal is to put together a core program for the National Johne’s Disease Demonstration Herd Project.  Recognizing differences in cattle herd production systems regionally and state needs and priorities, our goal was to keep the core aspects of this program to a minimum, while maintaining the minimum level of high quality data to achieve the highest priority (primary) objective of this project.

Primary Objective:

1. Evaluate the long-term effectiveness and feasibility of management-related disease control on development of Johne’s disease and infection on dairy and beef cattle operations.

The primary hypothesis to be tested is that control of Johne’s disease can be achieved through implementation of on-farm management practices to reduce transmission of infection to susceptible cattle.  This project will evaluate whether a flexible, voluntary, farm-specific process using different Johne’s disease control and testing strategies can be shown to consistently decrease the impact of Johne’s infection in herds in different states with different testing approaches and management systems.  Culling data, testing data and management data will be used to evaluate the effectiveness and feasibility of the Johne’s disease control program.

We recognize that effective and feasible control of JD is dependent upon many factors including 1) degree of implementation (limited resources of facilities and labor and conflicting herd health or other farm priorities), 2) biosecurity challenges including purchased cattle, 3) testing strategy (definition of testing strategy and adequacy for meeting goals, utilization of test results for monitoring or selection of cattle for management decision-making, poor test performance in herds), and 4) limitations of state resources in amount or type of support that can be provided to farms (insufficient testing capacity or access to testing and insufficient personnel).

We estimate that a minimum of 100 herds nationally is necessary to test the hypothesis that a reduction in the incidence of clinical disease or prevalence of infection will be evident 4 years after the adoption of a JD herd control program by each herd owner.  This estimate is based on the assumption that the best a priori guess of the point estimate (reduction) is 70% and the goal is to have an error margin of no more than +/- 10% on the final estimate.  With these inputs, the required number of herds is approximately 84 but we assume that there will be a 15 to 20% loss of herds attributable to factors such as sales and, hence, we recommend upward adjustment to100.   If a goal is to compare estimated proportions between subgroups of herds (cattle type, herd size, etc), many more herds will be necessary to ensure statistical significance.  Our group has not specifically addressed the latter situation.

Criteria for States Involved in Demonstration Herd Program

1. Active Johne’s Disease Advisory Committee within state
2. Minimum infrastructure within state to conduct program
   • Priority will be given to states with a substantial cattle population. Demonstration herds will be considered in states with fewer cattle if funds are available and the states also meet the following criteria.
   • Trained Johne’s Disease Designated Coordinator/epidemiologist
   • Laboratory capacity (or access to capacity) to perform required testing
3. Strength of proposal

Secondary Objectives:

2. Provide information and materials for education and training of public and private practice veterinarians and cattle producers.
3. Develop and evaluate management, testing, and monitoring strategies for use in control of Johne’s disease in cattle herds.
4. Create the opportunity for add-on projects within states to address important research objectives.  Specific questions that could be answered include:
   1. How well do the test data collected over time correlate with the information gathered from the Johne’s disease history and risk assessment (including clinical cull data) about the level of Johne’s infection on a farm?
   2. How well does environmental sampling correlate with shedding prevalence over time?
   3. Can we accurately measure implementation of management practices or risk mitigation?
   4. How often do we see test conversions – positive to negative with fecal culture and serology?
   5. What is the longterm outcome of a test result relative to advancing infection?  Do low shedders progress and at what rate?  How well does serology correlate with fecal shedding in longitudinal studies?

To achieve these objectives, core information will be shared across states participating in this project.  States will submit Demonstration Farm proposals to the USDA Johne’s coordinator, Dr Michael Carter, for review.  CEAH will serve as the coordinating center for data compilation, validation, and analysis.  Data will be captured via the Microsoft Access database program available from USDA-APHIS-VS Johne’s Disease Riverdale Office (Dr. Michael Carter).  Each state should work out confidentiality issues to ensure farm identifiers are not made available to public without consent.  The goal is to share core information from demonstration herds to achieve the objectives above, while allowing for flexibility and creativity among states in achieving additional specific goals and objectives.

Outcomes to be Measured:

1. Monitor disease
   1. Incidence of clinical disease
      1. Number of clinical JD cases in herd by year within each age cohort (lactations 1, 2, 3+) and by source (home reared or purchased) divided by mean cow inventory during year.
      2. Exit monitoring of clinical suspects by fecal culture, or ELISA with confirmation by organism detection method, is recommended until a producer has a good sense of the percent of clinical suspects that are in fact Johne’s cases.
   2. Prevalence of infection – preferably monitored by whole herd fecal culture or other organism detection methods, as well as antibody detection method (e.g., ELISA).
      1. The target is at least 80% of adult cattle in herd tested per year.  With very large program herds, a random subset of the adult cattle in these herds may be tested if resources in state are limited, using statistical subset sampling as described in VJDHSP. 
      2. At minimum, all cattle (or statistical subset) should be tested using ELISA and all ELISA-positive cattle in herd must be confirmed using fecal culture or an approved agent detection method.
2. Monitor secondary culls – (subclinically infected cattle)
   1. Culling due to test results needs to be defined and distinguished as a separate (secondary) reason for Johne’s culling
      1. If fecal culture is used – describe/categorize quantities shed and basis of culling
      2. If serology is used for culling – recommend culture confirmation of ELISA-positives as a goal.
3. Monitor Risks and Management
   1. Define risks using risk assessment tools
   2. Document interventions and management events

Herd Selection Criteria:

1. Basic enrollment criteria: The herd must have a history of clinical disease in the herd (more than presence of disease in a purchased herd addition).  Herds must be documented as infected by organism detection methods. 
2. Owner profile:  The herd owner must be willing to keep good records and have in place a method (not necessarily computerized) to do so.  This means individual animal ID and records of animal movement (sales, culls [including reasons], etc.) and individual animal health events.  The herd owner must plan to be in business for at least the next 5 years, and must have the time/labor/facility/cash resources necessary to implement a control plan.  The herd owner uses and cooperates with a herd veterinarian and is willing to cooperate with university, state, or federal veterinarians involved with the demonstration herd program.
   • The herd owner must be willing to allow the data to be shared in the national data collection effort (anonymity of herd identity would be assured).  
   • The herd owner must be willing to allow his herd to be used for educational purposes (producer education programs, etc.)  Participating herd owners should allow data, photographs, etc. to be used for educational purposes.  Educational programs involving farm visits may be helpful in the educational effort but are not mandatory.
   • The herd owner must be willing to initially set some herd goals for control of the disease and be willing to annually review these and assess degree of progress.
3. The herd must use a Herd Veterinarian or Accredited Program Planner that is actively supporting the farm and the Johne’s disease control program.
4. Farm Demographics:  We expect that states will include herds of different sizes and management systems and infection challenge, though not necessarily all of the categories below within each state. Because demonstrating change over time in a herd with small cow numbers or very low prevalence is difficult, a minimum herd size of 50 cows with an estimated prevalence of infection of 5% or greater is strongly encouraged.  However, smaller herds with higher prevalence or larger herds with somewhat lower prevalence may be acceptable.  If the product of cow numbers times estimated prevalence equals 300 the herd could be enrolled (examples:  30 cows with 10% prevalence or 100 cows with 3% estimated herd prevalence.  If the herd prevalence is unknown at the beginning of the program, infected herds having a minimum of 5% of the cows culled the previous year having signs compatible with clinical Johne’s disease would be an acceptable alternative.

Examples:
• Adult milking cow herd size (<100, 100  - 1000, >1000 milk cows
• Tie stall vs. freestall cattle housing
• Commercial producer vs. registered seedstock producers
• Infection Status/ Challenge/ Impact – based on fecal shedding and clinical cull rate due to Johne’s disease
  1. Higher Prevalence (10-50%+) based on fecal shedding or ELISA-positive or  >5% of adult cow herd culled with clinical Johne’s disease per year)
  2. Lower prevalence (<10% of cows fecal shedding or ELISA-positive or £1% of adult cow herd with clinical infection per year)

Procedures:

Outline

1. Define overall herd goals and specific goals relative to Johne’s Disease.
2. Collect baseline farm data as outlined in the Herd Plan Manual.
3. Complete Johne’s Risk Assessment and farm walk-through and document risks.
4. Define risks and recommend management changes to address those risks in a written herd plan. Risks are prioritized and the management changes recommended that are in line with farm goals, resources. Review Quarterly. Document events.
5. Define Testing Strategies to meet Johne’s control objectives
• Document how test results will be used in the farm plan
6. Annual review to revisit farm goals, resources, commitment, management and progress.

1. Define Herd Goals - A herd plan and farm goals for the control of Johne’s disease should be developed at the initiation of the program and reviewed at least annually.  This should be done with the herd veterinarian and the demonstration herd coordinator/risk assessor.  The USAHA/NJWG Dairy Manual describes general management/control program strategies used by producers for control of their Johne’s disease problem:
   • Maintain and manage infection prevalence – The overall goal is to minimize existing risks and manage introduced infection.  This strategy may be most useful in herds with low prevalence or with fewer identified risks.
   • Control – The overall goal is to reduce prevalence; reduce clinical infection and losses; and reduce premise contamination and potential for transmission.
   • Reduce or eliminate infection – aggressive testing, management strategies and timeline. 
2. The standardized risk assessment form developed by the NJDWG must be used for each herd.
   1. States can use their own risk assessment form too, but must use the standardized one in order to assist in the data collection effort. 
   2. Define risks using quantitative risk assessment tools (available through USDA-APHIS-VS and on USAHA website) performed at least annually. 
   3. Inter-rater variation should be minimized by risk assessment in these herds by the same person, if possible, each year.  These individuals should have participated in training conducted by USDA-APHIS-VS.
   4. Recommended management changes should be in line with farm goals and resources, and these should be reviewed quarterly with one of these serving as an annual review.
3. Testing -  All adult animals (including bulls) must be tested by culture (or other organism detection method) and ELISA at least annually.  Colony counts, or some standardized method, to categorize shedding intensity should be used.  If states cannot comply with this because of herd size constraints or laboratory capability, an alternative strategy of whole herd ELISA testing with culture of ELISA-positives is acceptable.  If test results are used for culling or herd management, a description of how test results are used should be included in the herd plan.
4. Environmental samples should be collected for culture at least annually and may be collected more frequently.  These samples can be a composite of fecal material (not a single fecal pile) collected from calving pens, feeding/loafing areas, alleys, and input to manure handling systems (spreaders, pits, lagoons). 
5. Minimum record keeping requirement
   • Herd Demographics
     1. current production per year
     2. production per cow
     3. Facilities – tie stall/stanchion, free stall, mixed
     4. % replacements purchased
     5. % replacements reared
   • Culling Data
     1. Culling rate
     2. Culling rate due to clinical Johne’s
     3. Culling rate due to Secondary Johne’s culling (subclinical cows culled as a result of a Johne’s test result).
     4. Age at culling, date at culling, purchased or home reared, Johne’s test results
   • Testing data
     1. Test Date
     2. Age or lactation number
     3. Days in milk on sample date
6. Minimum intervention strategies used: Use common minimum standards for interventions across all herds. Suggest modification of the same minimum management practices as used in the Program Standards for Beef and Dairy Herds p 13.
   
   Herd plans should emphasize risks from fecal contamination - Identify and mitigate risks from exposure to and ingestion of adult manure in environment, feed and water – especially exposure to young stock.
   1. Maternity area must be clean and dry and separate, or protected from manure from, other adult animals.
   2. Separate newborn calves from adults immediately or as soon as possible
   3. No pooled colostrum; Use colostrum form single identified, healthy, low risk  or test negative cow
   4. Calves must be fed milk replacer or pasteurized milk
   5. Calves and heifers must be kept free from exposure to the manure of mature cattle. House separately or, if housed together, prevent contact with adult manure by physical barriers.
   6. Prevent contamination of feed and water fed to young stock by manure from adults. Do not feed refusals from adult cattle
   7. Adult Cattle
      1. Identify animals contributing most to farm’s infection load (testing or clinical observation) and market early or separate and use targeted management to mitigate exposure risks.
      2. Acquire new animals from low risk herds or submit a fecal culture and blood for ELISA at the time of purchase and include these animals in the regular testing thereafter.
   8. Use separate equipment for manure cleaning and feed handling.  An acceptable alternative is to thoroughly clean and then disinfect this equipment after manure handling and before handling feed.  Acceptable disinfectants include a substituted phenol (Amphyl, Osyl, Wexcide, One Stroke, TekTrol), Virkon S (Trifectant), or other product labeled as being tuberculocidal.
7. Monitor Risks and Management
   1. Document interventions and management events on quarterly basis.
   2. Measure of herd implementation of priority management through reduction in herd Risk Assessment score at least annually.
8. Other perceived benefits of Johne’s control (Optional, not part of core program)
   1. Improved calf health.  Good records and analysis will be needed to document this.
   2. Decreased other clinical diseases (e.g., salmonellosis) in cows and/or calves
   3. Increased longevity of cattle in herd  

Outcomes to be Measured:

1. Monitor disease -
   • Incidence of clinical disease – preferably confirmed by fecal culture or other organism detection methods
   • Prevalence of infection – preferably monitored by whole herd fecal culture or other organism detection methods.  However, in some cases, whole herd ELISA with fecal culture of ELISA-positive animals may be the only practical method.
2. Monitor culls - 
   • Confirm the status of all culled cows with fecal culture if at all possible
   • ELISA can be used as an alternate if culture is just not possible but cultural confirmation of ELISA-positives should be the goal.
3. Monitor Risks and  Management -
   • Define risks using risk assessment tools
   • Document interventions and management events

Herd Selection Criteria:

1. The herd must have a history of clinical disease in the herd (more than presence of disease in a purchased herd addition).  Herds must be documented to be infected by organism detection methods.
2. Owner profile:  The herd owner must be willing to keep good records and have in place a method (not necessarily computerized) to do so.  This means individual animal ID and records of animal movement (sales, culls [including reasons], etc.) and individual animal health events.  The herd owner must plan to be in business for at least the next 5 years, and must have the time/labor/facility/cash resources necessary to implement some portion of a control plan.  The herd owner uses and cooperates with a herd veterinarian and is willing to cooperate with university, state, or federal veterinarians involved with the demonstration herd program.
3. Because demonstrating change over time in a herd with small cow numbers or very low prevalence is difficult, a minimum herd size of 50 cows with an estimated prevalence of infection of 5% or greater is strongly encouraged.  However, smaller herds with higher prevalence or larger herds with somewhat less prevalence may be acceptable.  If the product of cow numbers times estimated prevalence equals 300 the herd could be enrolled (examples:  30 cows with 10% prevalence or 100 cows with 3% estimated herd prevalence.  If the herd prevalence is unknown at the beginning of the program, infected herds having a minimum of 5% of the cows culled the previous year having signs compatible with clinical Johne’s disease would be an acceptable alternative.
4. The herd owner must be willing to allow the data to be shared in the national data collection effort (anonymity of herd identity would be assured).  
5. The herd owner must be willing to allow his herd to be used for educational purposes (producer education programs, etc.)  Participating herd owners should allow data, photographs, and etc. to be used for educational purposes.  Educational programs involving farm visits may be helpful in the educational effort but are not mandatory.
6. The herd owner must be willing to initially set some herd goals for control of the disease and be willing to annually review these and assess degree of progress.

Procedures:

1. Define Herd Goals: A herd plan and farm goals for the control of Johne’s disease should be developed at the initiation of the program and reviewed at least annually.  This should be done with the herd veterinarian and the demonstration herd coordinator/risk assessor.  The USAHA/NJWG Beef Manual describes general management/control program strategies used by producers for control of their Johne’s disease problem:
   • Maintain and manage infection prevalence – The overall goal is to minimize existing risks and manage introduced infection.  This strategy may be most useful in herds with low prevalence or with fewer identified risks.
   • Control – The overall goal is to reduce prevalence; reduce clinical infection and losses; and reduce premise contamination and potential for transmission.
   • Reduce or eliminate infection – aggressive testing, management strategies and timeline.
2. The standardized risk assessment form developed by the NJDWG must be used for each herd.
   1. States can use their own risk assessment form too, but must use the standardized one in order to assist in the data collection effort.
   2. The risk assessment for all herds initially enrolled in a state should be done by the same person, and this person should also perform this in subsequent years.
   3. Recommended management changes should be in line with farm goals and resources, and these should be reviewed twice yearly with one of these serving as an annual review.
   4. At least one of the farm visits or risk assessments should be done near calving time, if possible, to assess what is actually being done at this critical time.
3. Testing - All adult animals (including bulls) must be tested by culture (or other organism detection method) and ELISA at least annually.  Colony counts, or some standardized method, to categorize shedding intensity should be used.  If states cannot comply with this because of herd size constraints or laboratory capability, an alternative strategy of whole herd ELISA testing with culture of ELISA-positives is acceptable.
4. Every attempt should be made to get a sample for fecal culture (or other organism detection method) from all culled animals before they leave the farm and the reason for leaving, age, date, if the animal was purchased or home-reared, and test result must be recorded.  If samples from all culls cannot be obtained, the proportion sampled and the results must be recorded.
5. Environmental samples should be collected for culture at least annually.  These should preferably be taken near calving time.  These samples can be a composite of fecal material collected from calving pens (not a single fecal pile) or soil samples contaminated with feces which have been collected in the calving area or feeding/loafing areas.  Protocols for culturing soil are not well established, but  recent work from Australia shows success with treating soil as feces.
6. Minimum record keeping requirement – In states where the expertise and resources are available to conduct a full Standardized Production Analysis (SPA) are available, this is encouraged.  An alternative is the SPA-EZ which can be found at http://gpvec.unl.edu/spa/.  Minimum data to be collected annually include:
   1. % of cows diagnosed pregnant that calve (if pregnancy checking is done)
   2. % of cows that calve of those exposed to bulls
   3. % of cows that abort
   4. % of calves weaned of those born
   5. average weight of calves weaned
   6. average age of calves weaned
   7. % cows culled and culling data as described above
   8. % replacements reared
   9. % replacements purchased
7. Minimum intervention strategies used:
   1. Cull heavy fecal shedders.
   2. For herds using individual calving pens, these should be cleaned and re-bedded between cows. Keep calving area as clean and dry as possible. Minimize the density of cow and calf pairs as much as possible.
   3. Use feeding practices that reduce manure contamination of feed, water, and feeding areas as much as possible.
   4. Use separate equipment for manure cleaning and feed handling.  An acceptable alternative is to thoroughly clean and then disinfect this equipment after manure handling and before handling feed.  Acceptable disinfectants include a substituted phenol (Amphyl, Osyl, Wexcide, One Stroke, TekTrol), Virkon S (Trifectant), or other product labeled as being tuberculocidal.
   5. Cull (send to feedlot) the most recent progeny of animals with clinical Johne’s disease and those determined to be heavy shedders.
   6. Avoid spreading manure on pastures; at least those that will be grazed by heifers.
   7. Isolate scouring or unthrifty animals promptly.  Do not place in paddocks with heifers and do not return them to the herd until a provisional diagnosis is made.  These animals should not be isolated in a calving area.
   8. Raised weaned replacements separated from older animals if possible. Avoid grazing weaned calves behind, or with, cows (3 month temporal separation).
   9. Acquire new animals from test negative herds or submit a fecal culture and blood for ELISA at the time of purchase and include these animals in the regular testing thereafter.

A cooperative effort of the National Institute for Animal Agriculture and USDA, APHIS, Veterinary Services,
 in association with the National Johne's Working Group & United States Animal Health Association