Since we had the problem with a resistant type of worm a couple of years ago (brought in by a tup who had been wormed indiscriminately every 3 weeks) I now work with our vet on the type of wormer we use etc. This involves me collecting sheep poo at various times of the year for the vet to count the worm eggs.
As the last worm count was done in late Feb, to coincide with the ewes final vaccinations before they give birth. Though the worm egg count was low, it was decided to worm the ewes as it is know that with the stress of lambing and feeding lambs, the ewes natural immunity to worms is very low and this can quickly result in a lot of worm eggs being passed on to the pasture, which means that the lambs can very quickly become infected, and this can have a effect on how much they grow.
It was decided that May would next time to do another worm count, and to that end, Monday saw me busy collecting 3 different poo samples. One from the pet lambs, one from the tup and weathers and finally one from the ewes and lambs. The vet rang with the results on Friday and it was good news. The tup, weather and pet lamb's worm count was so low, it was hardly worth mentioning, the ewes and lambs, though higher than the other 2 samples, was also low. Evidently anything between 100 - 200 is low, but all of the samples I had taken in for testing were below this.
So what next! No stress of worming the sheep just yet. Another worm count to be done for the ewes and lambs (not the pet lambs) in 6 - 8 weeks time. Or sooner if I start to notice a lot of lambs with "pooy bums" that is not related to being put onto fresh lush grass. I'm also going to continue putting the homeopathic wormer into all the animals waters, it seems to be helping the situation. The vet and I are aiming to be in a situation where the meat lambs are not wormed at all. It's all down to timing, correct use of wormer and the correct dosage. I know that this way of working goes against what a lot of farmers do, and that is to worm lambs every 3 weeks regardless, with the strongest wormer going. But with a worm egg count costing around £30 and the smallest bottle of wormer costing between £50 - £60. I know which route I prefer to go down.