Central swine testing stations are locations where animals are assembled for the purpose of evaluating differences in performance traits under uniform conditions. Central stations are used to 1) acquaint and educate producers with performance records; 2) compare individual pigs' performance for traits such as rate of gain, feed conversion, and backfat; and 3) provide a supply of performance tested animals for seedstock and commercial producers. Appropriate use of central test stations will increase the rate of genetic change because of accurate data collection under uniform conditions.

Entry Requirements

1.Individual pigs must weigh at least 40 pounds when delivered to the station. Pigs should have a weight per day of age between 0.6 and 1.2 pounds when put on test. Entry pig weight and age should be reported in test station reports.

2.All pigs must have an interstate health paper stating that pigs are free from designated communicable diseases outlined by the participating test station. Details for a comprehensive health program are found in the next section.

3.If the pigs are purebred, they must be eligible for registration in the appropriate registry, and the pedigrees must be submitted to the test station manager before the first interim report.

4.Entry data should include the following:

A.Pig identification (ear notch, birth date, breed, registration number)
B. Breeder information (name, address, breeder mark)
C.Sire (name and registration number)
D.Dam (name and registration number)
E. Date

Health Program

All entries to a test station should meet health standards set by the state regulatory agency or test station committee and be from validated brucellosis-free, pseudorabies-negative herds. Breeders and their veterinarians should also certify that the herd has been free of clinical evidence of swine dysentery and tuberculosis during the 6-month period prior to entry of pigs at the test station. In the case of transmissible gastroenteritis (TGE), the period should be at least 60 days. Entries must be accompanied by a certification statement similar to the one in Appendix F, and a current interstate health certificate. Stations may require more stringent health regulations if deemed necessary. If barrows are tested, castration wounds should be well healed before delivery to the station.

Pigs entering test stations should be tested and be serum neutralization negative for pseudorabies at the following times:

  1. Within 30 days prior to delivery to the station, if pigs do not originate from an accredited PRV herd.

  2. Prior to sale. In addition, all animals should be tested for brucellosis at this time.

    No pigs will be accepted from herds that 1) show clinical signs of pseudorabies, 2) have had positive florescent antibody test to PRV, 3) have had PRV isolation, and/or 4) have had a positive reaction to the pseudorabies serum neutralization test. Pigs will not be accepted from such herds until it is subsequently demonstrated that the herd is free of pseudorabies.

Pigs should be vaccinated against erysipelas and atrophic rhinitis upon entry into the station and again before sale. Breeding animals should also be vaccinated against all strains of Leptospirosis. Test animals should be dewormed with a compound proven effective for control of internal parasites during the adjustment period before starting on test, and should be treated for external parasites with an approved product, such as Ivomec7, upon entry into the station, and as recommended thereafter.

Each station should publish in each sale catalog and also post on the station premises a description of the health program followed at the station. The following procedures are suggested for station operation:

  1. Move all pigs directly from farm of origin to the test station.
  2. Provide all visitors with station boots and coveralls during their visit.
  3. Allow no one to enter pens.
  4. Allow no visitors in the pen area for 35 days after pigs are delivered.
  5. Establish a policy that the attending veterinarian may choose a live pig for postmortem examination to aid in arriving at a diagnosis in disease outbreaks.
  6. Work closely with a station veterinarian on establishing sanitation procedures.
  7. Permit no visitors unless an attendant is present.
  8. Do not admit any pigs to the station for 30 days prior to a sale.

Testing Procedures

  1. All pigs must be grown under uniform management. Information concerning station management practices and chemotherapeutics used for treatment of parasites or disease should be made available to the public.
  2. A high energy, corn-soy diet with a minimum of 18% crude protein should be fed for the first 35 days after test initiation. Stations may wish to use a 16% CP diet for the remainder of the test period (Appendix A). The composition of the diet fed should reflect sex of the pigs being tested.
  3. The number of animals per pen should be determined by the size of the pen, allowing at least 10 sq. ft. per pig during the test, and extra (25 sq. ft.) for exercise. All animals comprising an entry should be the progeny of one sire. Larger pen units with more than one sire represented should not report pen feed conversion unless pigs are fed individually.
  4. Test animals should be grouped by gender. Boars, gilts, or barrows are to be tested in separate groups or pens. If possible, boars and gilts should be housed out of sight and smell of each other.
  5. There will be a minimum 7-day adjustment period from entry into the station to the beginning of the test, to allow pigs to acclimate to the station environment and lessen carryover effects from farm of origin.
  6. The average minimum on-test pen weight is 70 pounds and the maximum weight, 80 pounds. Any test station using on-test averages of more than 80 pounds does not meet NSIF guidelines. Individual pigs weighing more than 90 pounds when put on test should not be offered for sale. It is important to keep weights within the 10-pound limit because the factor used to standardize on-test weights is not accurate beyond that range. On-test weight should be reported for individual pigs in sale catalogs and reports. For stations using SEW procedures, pigs may be placed on test at lighter weights, but the test period should still encompass enough time for pigs to come off test at 240 to 250 pounds.
  7. On-test information to record includes:

    C.Feed offered

  8. As they approach 250 pounds, pigs should be weighed weekly and the pigs taken off test when the pen average falls between 245 and 255 pounds. Test average daily gain should be adjusted for deviations from the standard on-test weight, using an adjustment of .005 pounds per pound for each pound over or under 80 pounds. For SEW pigs put on test lighter than 70 pounds, use a factor of .004.

    NOTE: The software provided by the University of Georgia used 80 pounds for the average standard on-test weight. If a station chooses to use a lighter starting weight, the software will have to be reprogrammed. Average starting weights greater than 80 pounds are not appropriate.

    The formula for adjusting days required to reach a constant weight (usually 250 " 15 pounds) is:

    where a = 50 for boars and barrows, and a = 40 for gilts. If off-test weights for computing gain and feed efficiency are not taken at the same time it should be so stated in the sale catalog.

  9. Feed efficiency should be computed at the average off-test weight of 240 to 250 pounds. Stations should report whether a meal or pelleted ration was fed and the method used to weigh the feed. Volumetric measurements are not appropriate because environmental factors affect the accuracy of such measures. Report whether the feed was transported to the station in bag or bulk form. Summaries should include season and average temperature during the test.

  10. Backfat should be measured at the tenth rib at the time pigs are weighed off test at 250 " 15 pounds. The average of two measurements, 2 inches off the midline, taken on both sides of the pig, should be recorded if a metal probe or an A-mode ultrasound machine is used. If a B-mode (real-time) machine is used, a single measurement is sufficient; backfat depth should be measured at the midpoint of the loin, and should include the skin. NSIF recommends pigs be measured by a certified technician (see Swine Genetics Factsheet 16). If other backfat measurements are taken, an explanation should be made in the sale catalog or on the report. All measurements should be reported as adjusted to a constant basis, using the formula below.

    where b = -20 for boars, +30 for barrows, and +5 for gilts.

  11. Off-test data to record include:

    D.Loin muscle area (optional). If reported, adjust to a constant weight using the following formula:

    E.Weight when backfat and loin muscle area are measured, if different from weight off test
    F. Feed efficiency (optional)
    G.Soundness score (optional). See Appendix D.

Recommended Indexes

Environmental influences make comparison of pigs tested at different locations, at different times, or under different management difficult. Using selection indexes that are based on deviations from contemporary group averages will provide valid comparisons of animals within the same test group. These comparisons provide a basis for assesing genetic merit. Keep in mind, however, that indexes are not appropriate for making between group comparisons of animals. Note, also, that the following indexes are to be used strictly for evaluating performance and carcass traits and not for ranking animals for any maternal traits. Data must be adjusted to a constant endpoint before using in a selection index. Traits included in the indexes are defined below.

G =Average daily gain (ADG) recorded on an individual minus the mean ADG of contemporary group.
B =Backfat depth measured on an animal minus mean backfat depth of contemporary group.
F =Feed to gain ratio calculated for an individual or pen of animals minus mean F/G for all pens or animals (if fed individually) in the contemporary group.
M =Predicted percent lean calculated for an individual minus the mean predicted percent lean for the contemporary group.


Feed Conversion Measured:

A-mode backfat: I = 100 + 68(G) - 142(B) - 80(F)
B-mode backfat*: I = 100 + 52(G) - 92(B) - 68(F)
Predicted % lean: I = 100 + 55(G) + 11(M) - 76(F)

Feed Conversion not Measured:

A-mode backfat: I = 100 + 100(G) - 194(B)
B-mode backfat*: I = 100 + 78(G) - 115(B)
Predicted % lean: I = 100 + 83(G) + 14(M)
1 Complete information about the recommended indexes are given in Appendix E.
* Use this index if backfat is measured with a metal probe.

These indexes will average 100 for each test and should have a standard deviation of about 25. The test group should have approximately the following distribution:

Index Value
Percent of Animals
More than 150
125 to 150
100 to 125
75 to 100
50 to 75
Less than 50

If EPDs are reported, traits may be evaluated with similar indexes. The simplest index consists of all the EPDs added together. For example, if ADG, backfat and feed conversion are of interest, the index would be

I = 100 + EPDG + EPDB + EPDF.

Use of economic values (see Table in Appendix E) will weight the genetic information for the relative importance of each trait. In this example, EPD=s are available on ADG and predicted percent lean:

I = 100 + 6*EPDG + 1.1*EPDM


  1. Interim report. At least one mid-test report should be sent to consignors. This report will include information about on-test and interim weights, average daily gain, pen feed efficiency, and other pertinent data the station manager may wish to include. Test station managers should inform breed secretaries about consignors with pigs on test and station sale dates.

  2. Off-test report. The off-test report should contain average daily gain, feed efficiency, backfat, and indexes for individual pigs, along with contemporary group averages for each trait. If available, EPD's should also be reported, along with their source and method of calculation. Reporting of other traits, such as soundness, is optional. Report date of sale and sale order, if available.

  3. Summary report. These reports, and sale catalogs, must include contemporary group averages. All animals in the test-sale group, including those not making the sale, will be included in the contemporary group averages and indexes. Report the complete name, address, and telephone number of each consignor. Report breed, name and registration number of the sire of each animal consigned.

Sale Qualifications

Only animals with an index of 80 or higher within a contemporary group should be offered for sale. This will result in about 20 percent of all animals being culled. Stations may adopt higher standards. If EPD's are reported, make sure buyers are aware of the basis for comparison. It is quite possible that boars with phenotypic indexes below 80 could still be better than average when all animals in a breed are considered. NSIF recommends the use of EPD's instead of phenotypic selection indexes when possible.

Additional animals may be culled because of soundness problems or other genetic or structural weakness. Caution: These problems should be known to have a genetic basis or be so severe that a boar cannot function. If these additional criteria do not lend themselves to objective measurement, they should be scored. Structural soundness and underline soundness are examples of such traits. In all cases, an explanation of the system(s) used should be included in the reports and sales catalog. See Appendix D for details.