January 26, 2009

Drench resistant worms in sheep - dealing to dags

Sheep, farming, husbandry, disease, animal health, worms, internal parasites, dagging, solutions

By Dr Clive Dalton

What everybody knows

  • Dagging is the worst job on the farm- hated by everyone but accepted as part of the job.
  • If dagging was clearly listed in a shepherd’s job description, applicants would be scared away. Imagine “bonus for dagging” being featured? Yeah Right!
  • Dagging is a pain in the back, hips, knees and brain! These afflictions can only get worse with the average age of a sheep farmer being 55+ years. ACC statistics have always shown that 40% of sheep farmers have bad backs and have learned to live with the pain.
  • Shearers won’t dag sheep, as it’s a health and safety issue. They can also refuse to shear daggy sheep, as they are about as popular as damp sheep.
  • Dags are sheep dung, and salmonella and campylobacter love them.
  • The wool industry doesn’t want dags. ‘Average quality’ dry dags (with some wool yield) make around 20c/kg but low-quality dags are worthless. Wool brokers don’t trade in dung.
  • If you can get someone to dag sheep, the current cost is up to 70c/sheep. In the next few years – if there are any volunteers for the job left it could easily be $1/sheep.
  • Sheep are getting heavier and these costs will apply even if sheep handling devices are used rather than dragging sheep across the board.
  • The cost of dagging to the nation must be astronomical! I’d guess half a billion dollars if you added all things in like wasted time and medical costs for an aging farmer population. You could charge hip replacements at around $15,000 each and knees at $14,000 each. You may get a 15% discount for a pair!
  • So to solve the sheep industry’s problems, it’s no good waiting for increased returns. Farmers will have to cut costs with a vengeance and getting rid of dagging must be top of the hit list to produce low-cost sheep.

The old solution

There's no shortage of drench in attractive containers with
bright colours, supported by sales
promotions from free jerkins to golf clubs and iPods

  • Drench and more drench was the answer. Nothing was more simple! The farm staff felt they’d done a great job and killed all the worms – especially if the yards were full of tapeworms. The dogs got a good run and it was a good chance to school up young huntaways with frequent filling and emptying the crush pens.
  • And at least after drenching (if the product worked) the sheep dried up for a while to give you some respite from growing more dags. If it didn’t and sheep slowly started to scour again, then you drenched them again in a few weeks.
  • It was wonderful when the long-acting anthelmintics devices came along that stayed in the rumen and drip-fed anthelmintics. This was until worms started to develop drench resistance.
  • Sadly these old solutions are still used today by farmers who need to do some fresh thinking while drenching.

What needs thinking about now?

  • Dags are soft faeces that stick to wool and even to bare skin. So breeding bare-bummed and woolless sheep is not the solution. It will help, but there are far too many other issues with these sheep to complicate this approach.
  • The standard approach has been: worms = scouring = dags. Drench was seen as the way to fix all three but this approach needs to change.
  • Sheep don’t get up during the night to go to the loo - they lie where they are and let it flow! So if dung is soft, they’ll lie in it before morning and rise with soiled wool and more dung stuck to existing dags. So dags can multiply rapidly from the inside and the outside once they start.
  • ‘Marbles’ and ‘hand grenades’ (with low moisture content) don’t stick to wool – even if a sheep lies on them. Check sheep night-camp areas in a morning and see the little mountains of marbles. They are works of art! Then notice the great squashed heaps of plops or slops with the impressions of wool in them from overlaying.
  • Having a decent tail dock helps the muscles around the anus to eject faeces. Sheep (with tails) wag them when defaecating to help ejection and the two ligaments under the tail control this. So don’t dock tails off by the body and follow the Sheep Code of Welfare. Some stud ram photos in adverts currently show the very worst examples.
  • Notice how people who promote and sell drench to prevent dags don’t dag sheep for their clients. The last dagging they probably did would have been when they were young and fit, and only for a short time such as on work experience. It would be nice if a drum of drench came with a voucher for a week’s free dagging by the supplier along with own food and drink.
  • Key Point: If you mate rams and ewes this season that are genetically dag producers, then add 5 more years of dagging their progeny on to your current age! It would pay to buy the bigger drench pack that comes with an iPod to load with your favourite music to help relieve the pain when dagging on your own in the years to come. It’s worth a thought.
The solution – genetics
  • It’s interesting that more farmers and veterinarians are remarking that some sheep in a flock, regardless of the feed (sloppy or dry), need regular dagging and others don’t.
  • This is old news, but not much was ever done about it –other than drench the whole flock again, which was always the easy option.
  • If they’d looked closer they’d have seen that the ‘non-daggers’ produced marbles or hand grenades and didn’t poo their pants like the sloppy ‘daggers’ did.
  • There are enough farmers around now who can prove that culling persistently-daggy sheep will reduce the number of bales of dags in the shed and all the wasted time involved.
  • Some say it took a long time, and others say it was surprisingly quick once they became driven to fix the problem by health or labour problems.
  • Good research has shown that dags are inherited. The average of a few heritability estimates is around 25% which is not high like fleece weight, growth or FE resistance (around 35-40%), but it’s good enough to make some positive change if you crank up the selection pressure (Selection Differential) on both the male and female side. Note the word ‘both’.
  • So try this for logic. If ‘dags’ on the outside of a sheep are inherited, then what produces them on the inside, (measured by FCS) must be inherited too.
  • Remember the advantages of marbles. They are produced by healthy sheep, don’t stick to the wool and they kill larvae fast on the paddock.
  • So the genetic solution is simple – mate ‘marbling’ rams to ‘marbling’ ewes and you’ll be on fast track to breeding dag-free and worm resistant sheep in the one go. It’s scary that the job could be that simple.
  • It’s certainly worth thinking about and giving it a go. It’s not going to cost you any more and if it works, then life will be very much easier for both shepherd and sheep.
What to do

First step - drafting into clean and dirty mobs
  • Keep the job simple and cheap - so avoid consultants!
  • Check the faecal consistency score (FCS) of all rams to be used as well as their FEC. Remember that they should not have been drenched for at least two months (preferably more) before testing to get a decent estimate of their genetics.
  • FEC on it’s own is not good enough any more as you could easily end up with low-FEC dag-producers from soft faeces (plops, slops and scour). FEC and FCS must go together.
  • If you are worried about the accuracy of a single FEC/FCS, do a couple more a week or so apart to check repeatability.
  • Make sure the samples have been done at a reliable lab that has checked their accuracy. You need to ask for a High Dilution method to make sure no eggs are missed to get an accurate value for selection purposes.
  • You are not wanting to find out if the results justify giving the animals a drench, so it’s very important to explain what you are doing to your veterinarian.
  • There’s evidence now coming through from stud flocks using FEC/FCS to check their two-tooth and older rams, that they maintain their ranking among their peers, and they don’t seem to show the big worm-egg spring rise seen in ewes. This is good news.
  • So if you take repeated samples for FEC/FCS at different times on rams or ewes, and they differ by only a few hundred epg, then that’s quite acceptable. But if they vary by thousands of epg, then there‘s something funny going on and it would be wise not to select that animal.
  • If you have already joined the rams with the ewes, then wait till the rams have finished mating, and check their FEC/FCS after a month’s rest.
  • It’s the range in values that’s important, and it will either delight you (if it’s low), or make you very determined to get serious next season if it’s high.
  • You could easily have spread ‘dag-producing’ genes through the flock for the next five years and beyond.
  • Zero FEC with FCS 1 of marbles is the Holy Grail. If you have any of these rams, they are ‘non-dagging’ gold nuggets, and you cannot waste their genes by random mating them to any old ewes in the flock.
  • Get the faecal probe out (contact me for details) or use your finger and find some ewes with marbles or if there are not enough accept hand grenades as a mating group.
  • Then do a FEC on them to check they are zero or under 500epg. Your CFA old girls would be ideal to find these to form a nucleus of ‘no-dag’ sheep to increase their gene frequency in the flock. This trait must be given top priority in your selection.
  • This will get you going to deal with dags, and give you time to think about the next stage. Go back and check out the breeding chapter again.
Disclaimer This material is provided in good faith for information purposes only, and the author does not accept any liability to any person for actions taken as a result of the information or advice (or the use of such information or advice) provided in these pages.

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