Checking the manure for worm eggs is good, but it's not 100% accurate. Worm eggs don't pass at a steady rate. Worm loads are not even across all the animals in the herd, and testing each animal isn't practical. A calf could get a mouthful of worm eggs shortly before testing, and the worms wouldn't be mature enough to be passing eggs when you test. Some worms, like flukes, won't have eggs in the manure. Eggs from the different species are difficult to identify.
I have a several reasons I know our worming protocol is working better than our previous use of pour-ons.
1st. No more dinks at weaning!
2nd. Overall improved health in the calves at weaning.
3rd. Increased size, health, & weight of the yearlings, 2's, & 3's.
4th. Due to circumstances beyond my control, our Nov worming was delayed until Feb & Mar this year. We only had minor lice problems start to pop up but our vet mentioned last week that this has been a bad lice year. I'm convinced that consistent use of injectibles cut our overall lice problem.
