Targeted Selective Treatment (TST)Friday, 28th February 2020
By Dr Mackie Hobson
Targeted Selective Treatment (TST)
Why would we as farmers not want to reduce our worming costs by at least 25% and reduce the development of roundworm resistance on our farms?
Very few of us practice Targeted Selective Treatment (TST). We know 80% of all roundworms burden contaminating the veld/pasture come from just 30% of the flock so why do we always treat all our goats or sheep?
Yes, it does take a bit more time but the advantages can make a big difference to roundworm management and anthelmintic (dose) resistance development on your farm.
Targeted Selective Treatment (TST) involves deworming only those goats that need deworming or would benefit most from de-worming. We need to as an industry stop treating the whole flock and stop calendar dosing.
We know most resistance occurs to the drugs benzimidazoles, levamisoles ( ‘Koeldrank’ en Wit’ middles) and the ivermectin family.
An effective dewormer should reduce faecal egg counts by >95%.
A faecal egg count reduction test (FECRT) is the ‘gold standard’ to determine whether there is resistance to a particular active on your farm.
A FECRT is simple and just involves taking faecal samples from market goats before treatment and then 10-14 days after treatment (speak to your vet)
TST reduces anthelmintic resistance by reducing the amount of dose and increases ‘refugia’.
Refugia is the worms that have not been exposed to the dose so overall the worm population remains susceptible to the dose even although some resistant worms are present.
TST also identifies those goats that are more resilient and resistant to roundworms and those that are more susceptible to roundworms.
There are a number of ways to identify the goats that need to be treated or will benefit from treatment.
Effective ways are the use of the FAMACHA system, Body condition Score (BCS), the ‘5 point check’ or performance indicators such as weight.
- FAMACHA is the colour eye chart that identifies the level of anaemia (blood loss). It is an easy system that looks at the colour of the mucous membranes and your vet can train you and your farm workers on how to use it. The FAMACHA scale is 1-5
Only goats that are (5) white (4) pinkish-white and maybe the (3) pink colours are treated.
If eyes of pregnant or lactating ewes are 3 they should also be treated.
FAMACHA cards can be ordered from your vet.
- Body Condition Scoring (BCS) is another method that can be used and not treating the goats in goats in good condition helps maintain refugia.
- The 5-point check involves is another way of determining if goats need to be treated by examining the following:
- Eye (same principles as the FAMACHA system)
- Jaw (bottle jaw- odema due to reduced blood protein)
- Back (Condition Score)
- Tail (DAG score- faecal soiling)
- Nose (nasal discharge and ‘snorting’ can mean nasal bots are present (oestrus ovis) although goats have slighter few numbers)
The 5-point check may help determine if a goat with a FAMACHA score of 3 needs to be treated.
If you think it is too time consuming for you then to reduce some time you may want to reduce the number of goats examined by simply separating off those goats that lag behind and tire more easily when herded to the kraal and dose these. Then check the remaining goats and treat only those that need dosing according to any one of the above checks.