Faecal Egg Counting

Ideally, faecal egg counts taken every 3-4 weeks throughout the grazing season should be used to determine when to start dosing lambs and how often to do so. FECs can also be used to determine if a given group/class of wormer is working on an individual farm. This is called drench testing.

Taking a FEC is simple and quick once you know what to do. It involves taking 10 or more samples of fresh faeces (dung) ideally less than one hour old, from a mob of sheep. Samples should be kept cool and delivered to a vet or laboratory for analysis within 48 hours. Some agricultural merchants also offer FecPak services in their branches – ask you prescriber for more details. The results will give the number of worm eggs in the combined samples presented as ‘eggs per gram’ (EPG) of faeces. The number is an indication of the number of adult worms present in the gut of the sheep and can be used to:

• Tell if a treatment has been successful
• Help tell if a group of animals need to be treated
• Provide an indication of the level of contamination on a pasture

To check whether a treatment has been effective, a drench check should be completed. The length of time after treatment to do this test is dependent on the wormer group used.

• 2-LV (yellow wormer group): 7 days
• 1-BZ (white wormer group e.g. Rycoben™), 3-ML (clear wormer group e.g. Dectomax™), 4-AD (orange wormer group Zolvix™): 14 days

Doing a drench check provides an indication of how effective the treatment has been and does not automatically mean you have resistance.