You wont know without doing reduction tests on your sheep (before an after FEC with different wormers)
In the absence of doing^^^ (which i would recommend every time you worm sheep---what's the point in treating animals if you don't find out how well the treatment worked?) then a sweeping generalization would be that there is more resistance to white wormers than other drugs
NFU Cymru members and Assembly Members have been celebrating the role that Welsh farmers play in producing nutritious, high quality, safe affordable food during an event at the Senedd today on World Food Day (October 16).
The lunchtime event, which was sponsored by Llyr Gruffydd AM, included a special menu of fine Welsh produce.