|
|
| |
| |
 |
How common are drench resistant parasites? |
|
| |
|
How do I know if I have sheep drench resistance? |
|
| |
|
Will the use of capsules accelerate the development of resistance? |
|
| |
|
Why should I use controlled release capsules? |
|
| |
|
When should I use capsules on my sheep? |
|
| |
| |
Q. |
How common are drench resistant parasites? |
|
| |
A. |
Most Australian sheep properties have resistance to one or more of the action groups of anthelmintic compounds. Recent estimates are that over 80% of properties have resistance to benzimidazole (white) drenches, 60% show resistance to levamisole (clear) drenches, and over 30% show resistance to a combination of these two groups. Resistance to macrocyclic lactones (ML's or "mectins") has been reported across Australia.
|
|
 |
| |
Q. |
How do I know if I have sheep drench resistance? |
|
| |
A. |
Testing the efficacy of various compounds is the most reliable way. Your local veterinarian or Merial Territory Manager can give advice on how to set up this test. A drench resistance test should be conducted at least every second year. There are two tests available;
1. Faecal Egg Count Reduction Test - where the number of eggs after treatment is compared to the faecal egg count of an untreated group of sheep.
2. Larval Development Test - where faecal samples are collected from untreated sheep. The parasite eggs are hatched in the presence of various concentrations of anthelmintic. The number that hatch is compared to those that hatch in the absence of drench.
|
|
|
| |
Q. |
Will the use of capsules accelerate the development of resistance? |
|
| |
A. |
No. Every time any drench is used there is some degree of selection for the development of resistance. However, capsules can be used in a rotation programme, have a short-acting chemical tail at the end of the last dose being delivered and are recommended to be used in situations where refugia dynamics can assist in dilution after treatment finishes. All of these factors work to minimise the potential for resistance selection so a well-structured drench program that includes the use of capsules should not accelerate the selection process.
|
|
|
| |
Q. |
Why should I use controlled release capsules? |
|
| |
A. |
Administering controlled release capsules to pre-lambing ewes results in much cleaner pastures. Sheep grazing these pastures will have fewer parasites, and because worms can reduce the amount of milk produced by ewes, the ewes are likely to produce more milk for their lambs. This will assist the lambs in reaching the minimum recommended weaning weight of 20-23 kg that ensures a better survival rate, especially in adverse conditions.
|
|
|
| |
Q. |
When should I use capsules on my sheep? |
|
| |
A. |
Every farm situation is different so it is important for you to discuss an effective sheep-drenching program with your local sheep veterinary advisor or your local Merial Territory Manager.
A general rule of thumb for sheep graziers in temperature climates is to capsule ewes pre-lambing and follow up with a capsule to weaners at weaning or at the autumn break. Some oral drenching of other sheep may be required depending on the level of parasite infestation on your property.
|
|
|
