Johne's Disease

Utah Johne's Disease Advisory Committeee

Utah Johne's Disease Advisory Committeee was established in March-June of 2000 to develop a voluntary program for Utah producers in relation to Johne's Disease paratuberculosis).

The primary goals are:

1. Establish a Voluntary Certification Program
2. Educate producers and veterinarians about the program, disease and resources available
3. Assist in providing research support
4. Assist in procuring funding support

• United States Animal Health Association Committee on Johne's Disease National Johne's Working Group (NJWG)
• Johne's Information Center - University of Wisconsin - Madison (Dr. Michael T. Collins)
• International Association for Paratuberculosis

Program and Funding for Johne's Disease Testing

TO: Utah Dairy and Beef Producers
FROM: Utah Johne's Disease Advisory Committee
DATE: May 23, 2001

Johne's Disease (pronounced 'YO-knees'), a very costly disease of the intestinal tract and associated lymph nodes, is found in some herds in the intermountain west and across the country. There is much concern in our industry of the real hazard of many herds becoming infected in the next few years because cattle are being moved more widely than ever before, both domestically and internationally. The result of this movement of cattle could be the wide-spread introduction of this disease into many herds now, that would not be apparent for several years.

The Utah Department of Agriculture and Food (UDAF) has formed a state Johne's Disease Advisory Committee comprised of representatives of dairy and beef producers, veterinarians, USU Extension, and officials of the Department to study this issue and become pro-active in combating the disease. This committee has prepared a program wherein a producer can participate to either rid his herd of JD or protect himself from acquiring the disease through his normal production activity. In the last legislative session, the legislature appropriated some funding which will pay the laboratory costs for a producer to test 30 animals in his herd to determine the herd status. A national eradication program is also being considered this year in Congress, but likely will not be acted upon until late this year.

As producers in Utah, we have an opportunity to protect our livestock against Johne's Disease by participating in this testing program. Along with this letter is a description of the disease, how it spreads, how producers can find it and the best management practices to protect your operation against getting the disease. Farm income can certainly be enhanced when you are able to market your livestock or dairy cattle with a Johne's Free assurance to the purchaser, as well as the fact that you can be better protected in the cattle that you purchase for your own herd.

Another reason for much concern is due to public perception, by at least some individuals and groups, that Johne's Disease is related to or may cause Crohn's Disease in humans.

It is our goal to continue to assure the public of a wholesome food supply and to assure the dairy and livestock producers in Utah a healthy and viable business in the future. The Johne's Disease Program is integrated with the Utah Cattle Health Assurance Program offered by the Utah Department of Agriculture and Food. The UCHAP program provides an opportunity for producers to pursue an integrated herd management approach to the detection, control, and eradication of diseases within the herd. The result is a healthier, more productive herd and a safer food supply.

Johne's Disease Funding

The Utah State Legislature has established funding for laboratory testing of 30 cows per herd for Johne's Disease. Herds that test negative may qualify for Status Level One of the Utah Johne's Disease Herd Status Program. Such a designation is an indication to other livestock owners and consumers that your herd does not have Johne's Disease (at a confidence level of 85%). Herds that are found to have Johne's Disease present can then implement a disease control program. Funding for the tests will be available after July 1, 2001, but is limited to the first 200 herds who apply.

Where Do I Start?

Make application to participate in the program to the Utah Department of Agriculture and Food. Applications may be obtained from your veterinarian or county extension agent or from the Department by calling (801) 538-7161. Test tubes and information will be sent to your veterinarian.

Have your veterinarian collect blood samples from 30 cows (randomly selected from those which have had at least two calves). Your veterinarian will send the samples to the Utah Veterinary Diagnostic Laboratory at Logan, for testing. The veterinarian will bill you for his services but not for test tubes or laboratory fees. The Department will pay for test tubes and laboratory fees through the legislative funding.

The laboratory will report test results to the Department and your veterinarian. Your veterinarian will not be required to release the identity of your farm without your permission, based on veterinarian-client confidentiality.

Perform a Johne's Disease Risk Assessment of your farm with your veterinarian, based on the results of your testing and based on farm inputs and management practices. Identify potential points of risk on your farm for Johne's Disease.

Develop a Johne's Disease Management Plan with your veterinarian that addresses the elements of risk identified in your Risk Assessment. This plan should be used by you and your veterinarian to remain free of Johne's Disease or to control and eliminate the disease from your herd if the herd is already infected. The Utah Cattle Health Assurance Plan (UCHAP) can aid you in this. Individually identify all animals on the premise.

If the test results are all negative, you may wish to apply for Status Level One of the Utah Johne's Disease Herd Status Program. Application should be made to the Utah Johne's Advisory Committee by submitting your negative test results as well as a copy of the Risk Assessment, your Disease Management Plan, and a cover letter requesting such status. Send the application to:

Utah Johne's Disease Advisory Committee
Utah Department of Agriculture and Food
P.O. Box 146500
Salt Lake City, UT 84114-6500

Application to Enroll

Utah Cattle Health Assurance Program (UCHAP)

The Utah Cattle Health Assurance Program is an integrated herd management approach to the detection, control and eradication of diseases within the herd.

The program is built around a flexible core composed of management procedures, informed culling decisions and diagnostic surveillance.

The parties of this agreement are:

A.

Herd Owner:

__________________________

Farm Name:

______________________

Address:

________________________________________________________________

GPS Information

_________________________________________________________

Location:

County

_____________________

Town

____________________________

Phone number (area code):

________________________

Fax number:

______________

E-mail Address:

_________________________________________________________

B.

Herd Veterinarian:

_______________________________________________________

Representing (veterinary practice/clinic):

_____________________________________

Address:

_______________________________________________________________ __________________________________

Phone Number:

________________________

Fax number:

______________________

E-mail Address:

_______________________

C.

The Utah Department of Agriculture and Food, Division of Animal Industry Address: P.O. Box 146500, Salt Lake City, Utah 84114-6500 Location: 350 North Redwood Road Telephone number: (801) 538-4910 Fax number: (801) 538-7169 e-mail: agmain.erogers@email.state.ut.us

CORE MODULE

The parties agree to cooperate in a program to control diseases in this herd of cattle located at:

Premise:

______________________________

Location:

________________________

The parties agree as follows:

1. The herd owner agrees to
• Perform a Risk Assessment in conjunction with the herd veterinarian.
• In conjunction with the herd veterinarian, establish a written herd plan designed and tailored to control diseases on the farm. The herd plan should be developed using tenets of the best management practices as a guideline.
• Implement herd plan as developed.
• Notify herd veterinarian of problems and adjust herd plan as necessary.
• Participate in an annual review with the herd veterinarian to demonstrate implementation of the herd plan.
2. The herd veterinarian agrees to
• Perform a Risk Assessment in conjunction with the herd owner or representative.
• Establish, in cooperation with the producer, the herd plan tailored to reduce or eliminate disease on the particular farm. Utilize the "Best Management Practices" as a template for the establishment of the herd plan.
• Collect and submit diagnostic samples described in the herd plan or as needed.
• Participate in an annual review of the herd plan with the herd owner and monitor progress of plan on his regularly scheduled visits.
3. The Department of Agriculture and Food agrees to:
• Provide information about diseases and methods of control to the herd owner and the herd veterinarian as requested.
• Assist with the interpretation of diagnostic test results.
• Approve the use of the UCHAP logo by participating farms and issue a Certificate of Participation.

[ ] Yes, I wish to participate in the Core Module

Johne's Module

The parties agree to cooperate in a program to control JOHNE'S DISEASE in this herd of cattle located at:

Premise:

______________________________

Location:

________________________

A. The herd owner agrees to:

· Randomly test 30 cows from the herd which have had at least 2 calves

· Implement Best Management Practices to control Johne's Disease on the premise

B. The veterinarian agrees to:

· Collect random samples from 30 cows in the herd which have had at least 2 calves.(Veterinary fees for this service shall be negotiated between the veterinarian and the herd owner)

· Consult with the herd owner concerning Best Management Practices to control Johne's Disease in the herd

C. The Department of Agriculture and Food agrees to:

· Provide 30 blood collection tubes to the program participant's veterinarian

· Reimburse the U.S.U. Veterinary Diagnostic Laboratory the amount of $5 per ELISA test up to a maximum of 30 animals per herd. (Reimbursement and tubes shall be limited to funding granted by the legislature to the Department for that purpose.)

[ ] Yes, I wish to participate in the Johne's Disease Module

D. All Parties understand and agree that

· Prerequisites for entering into this agreement have been met.

· There will be no compensation or money paid to the Herd Owner for removal of cattle that are clinical cases and/or are test positive by serology or culture for infection.

· The department shall have no liability for damages, losses, or injuries incidental to or arising out of handling or use of the vaccine on the animals or other work performed under this agreement.

· Cancellation of agreement:

1. Herd owner may cancel at any time for any reason.

2. Herd Veterinarians may cancel at any time for any reason but the Herd Owner may apply for a new agreement.

3. The Department may cancel at any time if the owner fails to demonstrate compliance with the herd plan.

E. Confidentiality Statement -

Records relating to diagnostic testing shall be the property of the herd owner and shall be treated confidentially by UCHAP. Patient, Client, Veterinary relationship is recognized at all times with this program.

This agreement is not effective until signed by all of the parties.

Herd Owner:

___________________________________

Date:

___________________

Herd Veterinarian:

_______________________________

Date:

___________________

Administrator:

__________________________________

Date:

___________________

Division of Animal Industry, UCHAP

**UCHAP gives thanks to the New York State Department of Agriculture and Markets and Cornell University for their resources used in this program.

Utah Status Program for Johne's Disease

Utah Voluntary Johne's Disease

Herd Status Program for Cattle

(Adapted from U.S. Program - October 1998 )

Definitions:

Herd: a group of cattle managed as a separate and discrete unit not commingled with other groups of susceptible species.

All cattle on two or more premises geographically separated but on which cattle have been interchanged or where there has been contact between the premises is considered one herd. Contact of animals between separated premises under common management is assumed to have occurred unless complete separation and biosecurity measures between premises can be established by the herd owner or manager.

Herd member: any susceptible species of animal that is commingled with the herd.

Commingling: physical contact or exposure to manure or raw milk of susceptible species. For example, all cattle and other susceptible species grazed together or on the same area of a property or farm, at any time during any 12-month period, are considered to be commingled. Susceptible species include domestic and exotic ruminants such as sheep, goats, cervids and camelids. Exposure to manure via contaminated water or feed sources is also considered commingling.

Biosecurity: animal husbandry and hygiene practices designed to limit opportunities for exposure to M. paratuberculosis.

Animal identification: all cattle in a Program herd must be permanently and individually identified using an identification method approved by the State Johne's Advisory Committee. However, Level 4 herds must individually identify all cattle using a USDA approved official identification system. The identification methods approved by Utah JD Advisory Committee as of 8/15/2000:

USDA eartag

Tattoo

Registration papers

DHIA eartag

Microchip

Accredited Veterinarian: a veterinarian approved by the Deputy Administrator of USDA, APHIS, VS to perform functions required by State-Federal-Industry cooperative programs. For the Voluntary Johne's Disease Herd Status Program (VJDHSP) these duties include annual herd visits, animal testing, and producer education. All samples for Program testing must be collected by an accredited veterinarian or State or Federal animal health official

Accredited Laboratory: a laboratory that has passed an annual check test for Johne's disease administered by the National Veterinary Services Laboratories. All program testing must be conducted by a laboratory approved for the specific test being used.

Johne's Epidemiologist: a State or Federal regulatory health official who has demonstrated the knowledge and ability to perform the functions specified by the VJDHSP. The Johne's epidemiologist should be selected in consultation with the State Johne's Advisory Committee, State animal health official, Area-Veterinarian-in-Charge, and the National Program Coordinator.

National Program Coordinator: a USDA staff veterinarian who will assist State Johne's epidemiologists, State Johne's Advisory Committees, and the USAHA Johne's Committee with the administration and review of the Voluntary Johne's Disease Herd Status Program.

Herd Status Levels: herds may achieve status Levels of 1, 2, 3 or 4. Each level of increase indicates higher confidence in the Johne's disease free status of the herd. (Percentages shown on the flow diagrams in Appendix II represent a mathematical estimate of the probability herds at each level of certification are free of Johne's disease based on serial testing.)

Level achievement year: the year in which a herd met Program standards to be granted a specific status Level. For example, a herd completing Level 2 testing in 1998 which elects to remain at Level 2 would have Level 2 1998 status. Level achievement year is noted because continued monitoring increases confidence the herd is not infected.

ELISA or Fecal Culture Statistical subset: an ELISA test on or fecal culture of a statistically determined number of animals. The table in Appendix I shows the number of animals to include in Program ELISA and fecal culture statistical subset testing.

State Johne's Advisory Committee: an appointed committee which is the authority responsible for overseeing and coordinating the State's Voluntary Johne's Disease Herd Status program. The Committee may be comprised of any or all of the following:

Dairy producers - purebred, commercial and commodity groups

Beef producers - purebred, commercial and commodity groups

University Extension - beef and dairy

Veterinary practitioners - beef and dairy

Regulatory veterinary medicine - state, federal, and/or field services

Responsibilities of the committee should include, but are not limited to:

informing and educating the industry regarding Johne's disease

overseeing financial needs for state Johne's disease activities

recommending state policies with approval of the appropriate State authority on operating a Johne's disease program which enhances a Johne's disease herd status program, reduces the spread of Johne's disease and assists infected herds in managing or controlling the infection

setting standards for release of information on Program herd status

overseeing appeals of Program herd status

providing input to the USAHA Johne's Committee National Johne's Working Group for evaluation and revision of the VJDHS Program.

The duties of the Johne's Advisory Committee could be assumed by an existing animal health committee in the State.

Program Protocol

Confidentiality

Within the limits of each state's laws, it is important to maintain as much confidentiality of testing results as possible. At the same time, to promote the program, stimulate the market place to assign added value to animals from program herds and demonstrate the benefits of buying cattle from Johne's disease status program herds, it is desirable for owners of status level 1 - 4 herds to disclose their herd status. When possible, program herd owners should have the option of publicly withholding or promoting their herds' status level.

Entry to the Program:

Herds may enter the VJDHSP by two methods -Standard and Fast Track. All samples for Program testing must be collected by an accredited veterinarian or State or Federal animal health official and submitted to an accredited laboratory.

It is recommended that a farm or herd risk evaluation be done before completing herd testing for Level 1 Standard Track or Level 2 Fast Track. This evaluation would inform producers entering the program of existing herd risk factors for the spread of Johne's disease. A farm risk checklist may also be used as a yearly reminder of existing herd risk factors.

Additionally, Program herds should be encouraged to implement Best Management Practices as provided by the National Johne's Educational package to prevent the introduction and spread of Johne's disease in their herd.

Standard Track -

The herd must meet identification and commingling requirements described in the definitions. Herds enter the Standard Track Program by Johne's ELISA testing 301 second lactation or higher animals. No declaration of prior disease freedom is required. Negative test results on this initial test qualifies the herd for Level 1 status.

Fast Track -

The herd must meet identification and commingling requirements described in the definitions. Additionally, the herd owner must submit a signed statement that:

I am fully aware of the management and disease history of the herd and the property during the past five years.

Johne's disease is not known or suspected to have existed in the herd for the past five years or on the property during the past twelve months.

Cattle are not known to have been introduced from known infected herds during the past five years.

The above written statement and a negative ELISA test on a statistical subset of second or higher lactation animals qualifies the herd for Level 2 status. States may additionally require the herd veterinarian of record to co-sign the owner statement.

Previously infected herds -

Cattle herds previously culture positive for M. paratuberculosis may enter the program by completing Standard Track entry requirements. Infected (positive on an organism detection test) and/or test positive (positive on any Johne's test) animals must be removed from the herd before Program entry.

Johne's Disease Vaccinated herds -

Herds previously vaccinated for Johne's disease may enter the Program once vaccination has been discontinued. These herdsmust utilize fecal culture as the only test until enough non- vaccinated natural additions qualify for ELISA testing. The number of animals to test at each level remains the same.

Herds tested negative prior to implementation of this program -

Herds Johne's disease tested negative prior to the implementation of this program may be entered at an assigned Program Level determined after a review by the Johne's epidemiologist. That review must include:

verification that the herd meets the minimum standards for testing (fecal culture results can be used in place of ELISA results). Future Program tests must be performed in accredited laboratories. risk assessment of the number, source, and testing history of herd additions made after the first qualifying test.

Additionally, producers wishing to use the Fast Track must make the required written statements for the time period (five years) prior to the first qualifying test.

Animals to test: Random sampling will give the most confidence and should be used to select animals for testing when feasible.

When possible, the same animals should not be tested in consecutive testing rounds. Animals should be selected to be representative of the herd population. This program uses second or higher lactation animals as the most obvious indication of animal age. Detailed requirements for sample handling and submission must be provided by the testing laboratory.

Maintaining a Status Level : Producers may elect to remain at any level of confidence in either Track by conforming with the program standards and performing an ELISA test on 30 randomly selected animals of second or higher lactation every 10 - 14 months. A level achievement year for each herd should also be noted as continued monitoring increases confidence the herd is not infected.

Testing Intervals: testing intervals are every 10 - 14 months from the date the test samples are taken. Herds will be removed from the program if the testing interval requirements are not met, unless an extension has been received from the Johne's Epidemiologist and/or State Cattle Committee.

Biosecurity

A program herd must have biosecurity measures in place in order to avoid exposure to manure or milk from ruminants of unknown Johne's disease status. These measures include:

pooled milk from cows of unknown Johne's disease status should not be used to feed baby calves;

manure from Embryo Transfer donors or other "visiting" cows (e.g. transport cows that lay over at program farms for rest or to be milked) should not be allowed to come in contact with the program herd and this manure should not be disposed of on pastures or in a manner which would contaminate pastures or animal feed.

exhibition cows and calves (especially under 6 months old) should be hauled in cleaned and disinfected trailers and avoid commingling; (Animal exhibition, consignment sales and transport are considered situations of low M. paratuberculosis infection transmission risk. However prudent care and diligence about biosecurity is recommended), a program herd must not be commingled with or grazed behind susceptible species, (e.g. sheep, goats, farmed deer, camelids, non-program cattle.)

Program Levels

Flow diagrams depicting progression through each status level appears as Appendix II. Percentages on the diagrams represent mathematical estimates of the probability herds at each level or certification are free of Johne's disease infection based on serial testing. This program does not certify animals free of Johne's disease. Owners may elect for their herd to remain at any status level by ELISA testing 30 second or higher lactation animals every 10 - 14 months. Maintenance of Level 4 status gives the producer a high level of certainty that their herd is free of infection. With continual maintenance of Level 4 status, it could be assumed that there is negligible risk of infection from Level 4 herds.

All samples for Program testing must be collected by an accredited veterinarian or State or Federal animal health official and submitted to an accredited laboratory. If an animal is removed from the herd while ELISA results are pending, a fecal culture should be collected and submitted on hold to the laboratory. This will allow, if the owner wishes, an appeal of herd status to be made if the animal tests ELISA positive. (See Appeal Process, page 9).

Standard Track

The standard track is designed to allow entry to the program with a minimal investment of funds and gradually increases the producer's investment in the program. The standard track will require at least three years and four tests to reach Level 4.

Level 1- program entry requirements met, negative ELISA on 30 second or higher lactation animals. A sample size of thirty was selected to optimize herd sensitivity and herd specificity and maintain a fixed cost for all herds entering the program.

Level 2 - met requirements for Level 1, and negative ELISA on a statistical subset of second or higher lactation animals. (See Appendix I for the Herd Subset Testing chart.) The Level 2 testing must be completed within 10 - 14 months of any Level 1 testing.

Level 3 - met requirements for Level 2 and have negative fecal culture results on a statistical subset of second and higher lactation herd members. Bulls two years of age and older must be included in this testing. (See Appendix I for the Herd Subset Testing Chart.) The fecal culture must be collected within 10 - 14 months of any Level 2 testing.

Level 4 - met requirements for Level 3 and have a negative ELISA on a statistical subset of second or higher lactation animals. Level 4 testing must be completed within 10 - 14 months of any Level 3 testing. Level 4 status is maintained by achieving negative ELISA results on 30 second or higher lactation animals every 10 - 14 months.

Fast Track

The fast track allows producers to proceed to a higher status level of confidence more quickly than the standard track, and requires greater financial investment at program entry. The fast track will allow herds to reach Level 4 in two years with three tests.

Level 2 - program entry requirements for Fast Track met, negative ELISA statistical subset test of second or higher lactation animals. (See Appendix I for the Herd Subset Testing chart.)

Level 3 - met requirements for Level 2 Fast Track and have negative fecal culture results on 30 second or higher lactation animals.2 Level 3 testing must be completed within 10 - 14 months of any Level 2 testing.

Level 4 - met requirements for Fast Track Level 3 and have negative ELISA results on a statistical subset test of second or higher lactation animals. Level 4 testing must be completed within 10 -14 months of any Level 3 testing. Level 4 status is maintained by achieving negative ELISA results on 30 second or higher lactation animals every 10 -14 months.

Herd Additions

Heifers that have not calved and bulls less than 2 years of age:

from herds of equal or higher program levels -or-

from program herds which are one level below the purchasing herd.

Animals in this category may not be added to Program herds from non-program herds.

First and higher lactation cows, bulls greater than or equal to 2 years of age:

Level 1 - 3 herds - from herds of equal or higher level -or- from any other herd as follows:

ELISA test of addition(s) in the herd of origin within 30 days prior to entry to the program herd -and -

Submission of fecal culture from addition(s) within 30 days of arrival -and-

Testing of herd addition(s) in addition to required animal sampling numbers for the next required annual testing.

Herd additions are not granted the same status as the receiving herd until this additional testing is negative.

Additional risk of infection is incurred when animals are purchased from non-program herds. Non-program herds should be encouraged to ELISA test 30 second or higher lactation animals before a Program herd will purchase from them (i.e. non-program herds should be encouraged to achieve Level 1 status.) When possible, additions from non-program herds should be isolated from the program herd and biosecurity maintained until fecal culture results are reported negative.

Level 4 herds - from herds of equal level -or- from Level 2 or 3 program herds as follows:

ELISA test of addition(s) in the herd of origin within 30 days prior to entry to the program herd -and-

Submission of fecal culture from addition(s) within 30 days of arrival -and-

Testing of herd addition(s) in addition to required animal sampling numbers for the next required annual testing.

Herd additions are not granted the same status as the receiving herd until this additional testing is negative.

Additional risk of infection is incurred when animals are purchased from herds of lower status.

Replacements raised elsewhere: Replacements may only be raised with animals from equivalent status Level herds. Replacements must not be commingled with lesser status level animals or herds.

Embryo Transfer / Artificial Insemination: Program herds may utilize semen and embryos from any other cattle herds. However, embryos must be processed according to International Embryo Transfer Society protocols. Embryo transfer recipient cows must meet herd addition requirements.

The risk of transmission of M. paratuberculosis from semen is unknown. AI centers are encouraged to routinely test their bulls for Johne's disease and to remove for sale all semen from bulls found to be infected. All semen used in program herds must be processed according to Certified Semen Services standards.

Changes in Herd Status

Herd additions : The status of the herd will revert to the status of the lowest animal if Program herd addition requirements are not met.

Change of ownership: herd status is determined by the status of the lowest herd member. Therefore, when ownership of a herd or part of the herd changes and no new animals are added to the herd, the herd level remains the same. When ownership of a herd changes and the herd is commingled with another herd or herds, the resulting new herd shall be assigned the lowest level and achievement year of the herds combined to make the new herd.

Appeal Process

Appealing ELISA positive results: status of herds with ELISA positive test(s) is "suspended pending confirmation". Producers may elect to either leave the program or confirm the test results.

Confirmation of ELISA-positive cattle will be done by fecal culture. Fecal culture must be submitted within 45 days of notification of ELISA results. If found to be culture-negative, the herd may advance or retain its status Level. Additionally, the animal(s) must be included in the next round of Program testing if still resident in the program herd.

Appealing Fecal culture positive results: fecal culture-positive cattle will be assumed to be infected with M. paratuberculosis and the herd will have it's status revoked. Herds may reenter the program at Level 1 by following program standards.

If the animal owner wishes to appeal this decision, the herd is assigned a status of "suspended pending appeal". Appeal may be made using one of three means of proving the animal in question is not infected:

Necropsy of the animal with culture and histopathology of at least the ileum, mesenteric lymph node and ileocecal lymph node -or-

Biopsy of the ileum (full thickness) and mesenteric or ileocecal lymph node with histopathology and culture of the tissues and culture of a fecal sample taken at the time of biopsy -or-

Six separate fecal cultures from the animal on samples collected not less than 30 days and not more than 45 days apart.

The herd Johne's disease status will be suspended until all testing is completed. Only negative results on all tests on all samples will allow the herd to advance or retain it's Program Level.

Appeal of status for other reasons: herd owners may appeal any decision or discuss extenuating circumstances that prevent compliance with the program rules to the State Johne's Advisory Committee.

A sample size of 30 was selected to reduce cost while maintaining acceptable accuracy. Return to text.

A history of Johne's disease freedom for five years prior to program entry adds sufficient confidence to allow Fast Track herds to test 30 animals rather than the statistical subset used in the Standard Track at to obtain Level 3 status. Return to text.

Appendix I - Herd Subset Sampling

PLEASE NOTE - The sample numbers below have been calculated based on the following assumptions:

The cattle to be tested are in 2nd or higher lactation

For these calculations, 25-percent test sensitivity of the ELISA and 40- percent test sensitivity of the fecal culture were assumed (this were the consensus estimates of the Herd Status Committee for subclinically infected cows in first of higher lactation, and no changes were made for the older population sampled For these calculations, 100-percent test specificity of the ELISA and fecal culture was assumed (given follow-up of all ELISA positives with fecal culture) The confidence of detecting infection (at least 1 test-positive cow), if present at a true prevalence of 2 percent, is 95 percent Sampling without replacement (hypergeometric distribution)

No. cows in herd of 2nd or higher lactation No. cattle to sample

(2nd lactation or higher)

ELISA Fecal culture

less than 300 test all test all

400 test all 313

500 test all 324

600 531 332

700 540 338

800 547 342

900 552 345

1000 580 360

Note: In smaller herds, all cattle second or higher lactation must be tested. In herds with fewer than 30 second and higher lactation animals, first lactation animals must also be tested.