Pre-treatment faecal egg counts (FEC's) of 12 animals are compared against FEC's 10-12 days post anthelmintic-treatment to calculate the percentage faecal egg count reduction for each anthelmintic treatment.
An untreated control group is usually recommended. Larval cultures are used to determine which parasite genera were present at the commencement of the FECRT, and which of those parasites are resistant to any of the anthelmintic treatments.
The optimal time to undertake the Drench Resistance Test is in the spring or autumn when parasite levels are usually at their highest, and when most of the parasite genera are present.
The drench resistance test is best performed on young animals (less than 1 year of age) as their less developed immune system are likely to result in higher and more varied parasite burdens.
Animals to be used in the test must have been present on the farm for a period of at least 6 weeks.
Twelve animals will be required per treatment group plus an additional 12 animals for an untreated control group.
A composite (mob average) FEC for the test animals must be at least 500 epg (although a FEC higher than 700 epg is desirable) before the Drench Resistance Test can be performed.
Sampling process
On "Day 0" individual faecal samples are collected from 12 animals for each anthelmintic being tested (plus the untreated control group if used). They are ear tagged with numbered tags, weighed and then accurately drenched (with a syringe) with the anthelmintic being tested. Refer to the Faecal egg counting submission form for detail of how to sample
The control group does not receive any anthelmintic treatment
The faecal samples are sent for individual egg counting and a pooled larval culture is performed to see what parasites are present in the animals
On "Day 10", individual faecal samples are again collected from all animals and sent away for egg counting
Any treatment groups that show a positive egg count will be larval cultured to determine what parasites are surviving the drench
A full Drench Resistance Test report will be delivered by your Animal Health Representative who will explain the results in detail and discuss management options
For further information, to make arrangements for testing or to speak with one of our animal health team about this service, please contact our Ravensdown Customer Centre on 0800 100 123.