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Faecal Egg Counts For Determining Drench Timing Effectiveness

I am often asked how frequently do I worm my dairy goats and what drench do I use? I wish there was a straight forward black and white answer to this question and anyone who has dairy goats will know that there are very few drenches that are registered for use in dairy goats and a lot of them come with the disclaimer “not for use in animals producing milk for human consumption”. There is also a lot of worm resistance to drenches.

So, when do I worm? When my faecal egg count results tell me I need to! I never drench without doing a faecal egg count first and then if I do drench, I do another faecal egg count approximately 10 days later to make sure the drench has worked.

Ok so what is a Faecal Egg Count? It’s a measure of the number of worm eggs per gram of faeces. The procedure is to collect fresh dung samples, weigh out a specific amount, add a saturated salt solution and then using a special microscope slide that is marked into sections, a count of the number of eggs is made. This count is entered into a calculation that works out the “eggs per gram of faeces.

If the number of eggs per gram is above a certain figure, then I will drench. Even then it can be more complex – if the number of eggs per gram is borderline and they are strongyle eggs then I will make a judgement based on the eye mucous membrane colour (Famacha score). The basis for this system is an eye chart that has been developed as an anaemia guide. If the Famacha score is 3, 4 or 5 then I will drench. This is a practical, subjective measure of the degree of anaemia caused by the presence of Haemonchus contortus (barbers pole worm).

By deworming only those goats that need it, development of drug resistant strains of worms is slowed and the effective life of a given drench on a given farm can be prolonged. By using these techniques, you can control worms effectively without wasting money on unnecessary drenches and without contributing to the increasing problem of worm resistance.