Guideline for the evaluation of the efficacy and safety of anticoccidials (WAAVP guidelines)

The World Association for the Advancement of Veterinary Parasitology (WAAVP) is a not-for-profit organisation for scientists who study the parasites of non-human animals. The guidelines developed by the international expert working groups of the WAAVP assist in the international harmonisation of standards and procedures for the evaluation of veterinary chemical products. The WAAVP guidelines for evaluating the efficacy of anticoccidials aim to establish uniform international standards regarding the demonstration of efficacy of new anticoccidial drugs.

To evaluate the efficacy of anticoccidials in chickens, turkeys, pigs, dogs, cattle and sheep the Australian Pesticides and Veterinary Medicines Authority (APVMA) has adopted following WAAVP guidelines:

  • Holdsworth, P.A, Conway, D.P., McKenzie, M.E., et al., 2004. World Association for the Advancement of Veterinary Parasitology (WAAVP) guidelines for evaluating the efficacy of anticoccidial drugs in chickens and turkeys, Veterinary Parasitology, vol. 121, Issues 3–4, pp 189–212.
  • Joachim, A., Altreuther, G., Bangoura, B., et al., 2018. WAAVP guideline for evaluating the efficacy of anticoccidials in mammals (pigs, dogs, cattle, sheep), Veterinary Parasitology, vol. 253, pp 102–119.

These guidelines are to be used in conjunction with the APVMA’s efficacy and safety guidelines (Part 8).

The APVMA notes that in some instances the WAAVP guidelines advise that some aspects of the efficacy study recommendations should correspond to standard commercial practice according to country and market requirements. We also recognise that because of Australia’s unique environmental and geographical features, farm management practices, animal breeds and parasite burdens and their population dynamics, there are some differences between the WAAVP recommendations and our recommendations for products that are to be registered in Australia. The following additional guidance is provided for applicants proposing to register poultry anticoccidials in Australia:

1. Dose determination studies (battery trials)

  • You should develop data for each coccidial species for which a claim is made and also for mixed infections of those species.
  • Artificial exposure is usually induced when chickens are 2 to 2.5 weeks old.
  • It is desirable that the test coccidiostats be mixed by the testing laboratory into the basal ration, avoiding cross contamination with other coccidiostats.
  • This short-term trial usually runs for 8 days after infection
  • The infective dose of sporulated oocysts is usually administered 2 days after medication with the coccidiostat has commenced.
  • Individual administration of oocysts directly into the crop of each chicken is recommended.

2. Dose confirmation studies (floor pen trials)

  • A suitable facility for such a trial would be an open-type shed with deep litter over a well-drained concrete floor, containing 8 to 12 pens on each side of a central passageway, each with a minimum capacity of 100 broiler type chickens.
  • This will allow the testing of three potential coccidiostats and a control, and with 4 to 6 replicates, suitably randomised for each treatment. A treatment with a reference coccidiostat may be included, if desired.
  • Coccidial exposure, normally with mixed infections, should be sufficient to produce a clinical effect, but preferably with at least 10 to 15% mortality in the unmedicated controls.
  • Artificial exposure is usually induced when chickens are 2.5 to 3 weeks old.
  • A floor pen trial runs for about 8 weeks.
  • Efficacy can be evaluated by criteria such as:
    • mortality, autopsy and lesion scores on dead chickens
    • lesion scores on 3 to 5 randomly selected chickens from each pen at, say, 5 to 6 weeks of age.

3. Field trials

  • Field trials should be conducted in 2 or 3 different climatic areas to demonstrate the utility of the anticoccidial agent under commercial conditions.
  • Commercial facilities normally available for such trials are not ideal for the accurate assessment of coccidiostats because there are marked variations in environmental conditions from farm to farm and from shed to shed.
  • Field trials involve many sources of error, and one should recognise their limitations, but they are highly desirable to show that the coccidiostat can be efficiently mixed in commercial feed.
  • You should make every effort to secure uniformity of management and facilities, including housing, ventilation, brooding, and the type and distribution of waterers and feeders. As far as possible, the chickens should be uniform in strain, batch and sex.
  • You should keep samples from every commercial feed delivery for check analyses of levels of coccidiostat to ensure that the feed has been mixed accurately.
  • The following housing arrangements (listed in order of preference) can be used:
    • Two or 3 sheds of identical size, divided into 3 or more equal pens.
    • Four equal sheds for cross-wise comparison of 2 coccidiostats.
    • Two equal sheds, with one coccidiostat in each.
    • An equally divided shed to test 2 coccidiostats, with provision for some controls on non-medicated feed to be placed in each half in a secure enclosure.

Most field trials depend on natural exposure, and the replication of treatments and trials is highly desirable.

The following are the usual criteria for evaluation:

  • Mortality and autopsy findings.
  • Lesion scores at 5 to 6 weeks on 5 randomly selected chickens from each group.
  • Average weight at slaughter, feed conversion ratios, and the economic performance of each group.

4. Compatibility

Some evidence of the compatibility of the coccidiostat with various other feed additives is desirable. Overseas data may be considered.

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