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Why test before you drench if you already know the answer?

Why test before you drench if you already know the answer?
Deb Maxwell

When you hear the message, WormTest before you drench, do you think to yourself, "Why bother with this extra cost when I know they need drenching?”

That’s what I used to think and I’ve heard many producers say the same.

But that’s changed and now my sheep need far less drenching, and mostly I have no idea when they are wormy enough for a drench, making the tests far more valuable. Let me tell you my story…

I’m Deb Maxwell, previously a sheep extension officer with DPI Qld and the Sheep CRC. I’ve also run a small stud flock of Merinos for 18 years, at Dalby in Qld, then at Guyra in northern NSW. These are moderate to high rainfall areas where barber’s pole worm is predominant.

As a good sheep extension officer I worm tested when I thought a drench was needed and just like so many producers, I was right over 90% of the time.

Sometimes I’d still get caught out and sheep would die—I found this very frustrating, after all, in my job, shouldn’t I know better?

Luckily for me I became part of the Sheep CRC’s WormBoss team, helping put together the regional programs and also implementing it in my flock.

What a difference it made to my sheep! Some of this information was relatively new research—the principles were not new, but some of the specifics of what to do and when to do it were.

Once I went away from an unplanned approach and followed an integrated worm control program, each worm test was suddenly useful—I was now wrong in my guesses about 90% of the time, so they were telling me something I didn’t know. Why?

When I relied solely on drenches in a moderate to high rainfall area, the pasture was highly contaminated with worm larvae most of the year, so it really was as easy as counting off about 5 weeks in summer from the last drench to guess they’d be wormy.

Now I use a number of control strategies: grazing management, breeding for resistance, choosing effective drenches based on resistance testing and using those drenches wisely in conjunction with testing and drenching. The main effect has been to drastically reduce the contamination of the pastures, so it takes much longer before sheep need a drench.

For the first 2 years of the new program I tested when I thought they needed drenching—based on my past experience. The results would come back, and no, they hardly had any worms. I’d go another few weeks, thinking they must build up fast soon and then I’d panic and think, “Oh, I better just drench them, I haven’t got time for a test before they’ll start to die.”

I actually did that once as I was just about to go away for a week or so, but sent a test off at the same time on my way to the airport. Goodness, what a waste of time and worry—they were still way off having needed a drench.

Over two years I gradually increased my faith in the program based on my new experiences and came to realize that I no longer had any idea what the test results would be each time, because it was many months longer before they needed drenching. And that’s how it should be—there’s no point testing if you already know the answer.

I tested far more than was needed during that first year or two, but for me that was part of learning that it worked. Testing is not all that often now.

An integrated program has allowed me to reduce my drenching of each mob from about six times per year, including one long acting treatment prior to lambing, to one or rarely two short acting drenches and one long acting treatment (now in autumn as part of my grazing management strategy). The tests results now have a high value and a death from worms is extremely rare.

If you are in a low rainfall area where only one or two drenches per year are needed anyway, I’d still always test before I drenched. But in the moderate to higher rainfall areas, ‘Testing before you drench’ should be part of an integrated program.

I helped develop each of the eight WormBoss regional programs. My job was to make them as easy to implement as possible.

I had a lot going against easy implementation on my place: one of the wormiest areas of Australia, both scour worms and barbers pole worm, no cattle to assist my grazing management, and a stud flock using all my paddocks at a critical time.

Nevertheless, implementing the WormBoss worm control program for my region, plus the Drench Decision Guide for the day-to-day decisions, was very easy and extremely effective. In fact it’s easier on the brain, less work and less worry than not following the program.

Give it a go, it’s probably easier than you think and you can try it out with just one or two mobs at first.