Measurement of Feed Carryover Level

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Definitions

  • Feed Carryover Level (hereafter Carryover refers to Feed Carryover Level) is the contamination of a feed with another material or feed that originates from previous use of the same equipment.

Objectives

  • To establish uniform methodology for the use of feed manufacturing facilities to consistently and accurately measure feed carryover level.

Rationale for Determining Carryover

  • Thorough cleaning of manufacturing and distribution equipment following every batch of medicated feed is impractical and is not required if appropriate precautions are taken.
  • Carryover of drugs in feeds needs to be managed so that it does not negatively impact on animal and human health.

Items to Consider When Developing Procedures to Determine Carryover

General Principles

The following principles shall be considered when developing the procedures to determine carryover in a particular facility:

1. Schedule of tests

Determination of carryover shall be conducted at least once every ten years to establish the benchmark for the facility. Determination of carryover shall be repeated after any installation or major repair or modification to any manufacturing equipment from the mixer to the end of the production line.

2. Testing Procedures.

Testing procedures a through g shall be repeated a minimum of five individual times as an indication of range and repeatability. The highest carryover value of the five individual sequences tested shall serve to determine carryover level of the facility.

  1. Manufacturing Procedures

    The test batches shall be manufactured using the facility's current feed manufacturing practices, e.g., sequence of ingredient addition to the mixer, mixing time and batch size shall be those used under normal conditions of operation. Batch A shall represent a full batch size manufactured by the production line being tested. Batch B shall represent a full batch size to which the measured carryover level will be applied. In cases where carryover assessment is required for batch sizes smaller than that used to establish carryover, the level of carryover assigned will be prorated against that determined by the full batch size. (Carryover level will be doubled for batch sizes 50% of that used to determine protocol, multiplied by a factor of four for batch sizes 25% of that used to determine protocol, etc.).

  2. Identification of Production Lines

    The carryover of a feed manufacturing facility shall be established using production lines and equipment specific to the facility. Where distinct production lines or pieces of equipment exist within a facility, each shall be represented at least once in the five individual tests.

  3. Selection of Test Substance

    The test substance is something that can be measured to evaluate carryover

    The following criteria shall be considered when choosing the test substance:

    • The method to determine the level of the substance shall be highly reproducible and have a low variation.
    • Only one ingredient shall contribute to the concentration of the test substance in Batch A unless the contribution from other ingredients can be verified.
    • Acceptable test substances would typically be medicating ingredients. Non-medicated tracers might also be acceptable provided that the baseline levels in both test batches could be established through analytical testing.
  4. Level of Test Substance in Batch A

    The level of test substance in Batch A shall be sufficiently high enough to allow detection in Feed B at the carryover being established, e.g., determining a 3% carryover requires addition of test substance in Batch A at 33 times the detection limit. Sample results indicating not detected shall be interpreted as equal to the detection limit.

  5. Ingredient Testing

    Where a medicating ingredient is used as the test substance, the facility may want to test unmedicated supplements or premixes used in the manufacture of this batch of feed to determine whether there is any baseline contamination of the batch with the test substance. Where the test substance is a trace mineral, the facility shall determine the baseline level in at least the second batch of feed (Batch B).

  6. Sampling Procedure

    For each of Batch A and Batch B, ten spot samples representing the full batch shall be taken at equally spaced intervals at the end of the production line being tested and then combined into one composite sample for laboratory analysis.

    Take spot samples by holding a small box, cup or scoop in the stream of feed and collecting 10 equally sized spot samples at the end of the production line being tested (for a total composite sample size of between 250 and 500 grams for dry feeds and between 500 and 1000 grams for Total Mixed Ration (TMR) mixes of feed).

    The entire sample for both Batch A and Batch B shall be submitted to the designated laboratory. Feed Program, Canadian Food Inspection Agency (CFIA), policy does not allow for introducing error by sample splitting.

  7. Assessing Sample Results

    For Batch A, the sample results will be considered to represent the level of the selected test substance for that batch.

    For Batch B, the sample results will be considered to represent the level of carryover for that individual sequence. Sample results indicating Not Detected will be interpreted as equal to the detection limit. Carryover of the facility will be equal to the highest level of the five sequences tested.

3. Corrective Actions

Should the initial determination of carryover not meet the desired standard of the facility, additional testing may be performed following the same procedures or new procedures if the feed manufacturing facility determines that changes in procedures are required. Where changes are required to manufacturing procedures to achieve the desired results, these modifications shall be made to the standard operating procedures in the feed manufacturing facility.

4.Written Procedures

The procedure for the measurement of carryover must be defined

The written procedure shall include:

  • Description of the production line to be tested for each of the five sequences to be tested
  • Identification of the test substance which will be used to determine carryover and the level to be included in Batch A
  • Details of the procedures to be used to manufacture both batches of feed, e.g., batch size, mixing time, any cleanout procedures prior to manufacturing Batch A*

* The test batches shall be manufactured using the facility's current feed manufacturing practices.

5.Documentation and Records

The following documents and records are required:

  • Written procedure used to determine carryover
  • Verification records of carryover test including:
    • testing date
    • mixing sheet/batch sheet for the test batches
    • details of manufacturing procedures for the test batches
    • analytical reports for laboratory result
    • calculations used to determine carryover
  • Equipment maintenance records

Appendix I Procedure for the Measurement of Feed Carryover Level

  1. Prior to conducting the test(s) to determine carryover, ensure the batch before the test batches does not contain the test substance or any other ingredients that could interfere with the determination of the level of the test substance. The mixer and the manufacturing equipment in the production line being evaluated shall be flushed using the facility's standard cleanout procedures or an unmedicated feed that does not contain the test substance should be manufactured.
  2. Begin by filling the mixer with a batch of feed that contains the intended concentration of the test substance. The batch size for Batch A shall represent the full batch size for feeds manufactured on this production line.
  3. Send this batch of feed through the entire production line that has been selected.
  4. Confirm the presence and level of test substance in the first batch of feed (Batch A) by taking 10 spot samples at evenly distributed intervals at the end of the selected production line. Take spot samples by holding a small box, cup or scoop in the stream of feed and collecting 10 equally sized spot samples at the end of the production line being tested. Combine these 10 spot samples into one composite sample (between 250 and 500 grams for dry feeds and between 500 and 1000 grams for Total Mixed Ration (TMR) mixes of feed) for laboratory analysis. The entire sample shall be submitted to the laboratory.
  5. Fill the mixer with a batch of feed that does not contain the test substance, and send through the same production line as the previous batch. The batch size for Batch B shall represent the batch size for feeds which will be impacted by carryover. The test substance measured in this batch will serve as a marker for the amount of feed carried over from the previous batch of feed for this particular sequence tested.
  6. Send this batch of feed through the entire production line that has been selected.
  7. Confirm the amount of the test substance carried over into the second batch (Batch B) of feed following the same procedures outlined in step 4.
  8. Repeat steps one through seven a minimum of five times ensuring each distinct production line or piece of equipment is represented at least once.
  9. Send the ten composite samples (one from Batch A plus one from Batch B for each test, maintaining the identity of the respective test they were obtained from) to the designated lab with the required forms or labels fully completed.
  10. Assess sample results as follows:
    • For Batch A, the sample results will be considered to represent the level of the selected test substance for the batch.
    • For corresponding Batch B, the sample result will be considered to represent the level of the selected test substance for that specific test.
      Sample results indicating not detected will be interpreted as equal to the detection limit for the test substance.
  11. The following calculation will be used to calculate carryover for each of the five sequences tested.

    (Level of test substance in Batch B minus Baseline level if any) (x 100%)

    ÷

    Level of test substance in corresponding Batch A

  12. The feed carryover level of the facility shall be the highest result of the five individual sequences tested.
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