January 2, 2009

Sheep Farm Husbandry - Castration and Tail Docking

Castration, tail docking, age, methods, welfare issues

By Dr Clive Dalton

These procedures have been carried out for centuries, castration to reduce the number of males on the farm, and docking tails to avoid the growth of dags that attract blowflies. So the term “docking” for both these operations, done at the same time.

Both involve animal welfare issues as they are done by farmers (and not by veterinarians), and no anaesthetics are used

At what age?
  • Ram lambs grow much faster and are leaner than castrates (wethers) and so make more money in the meat trade. So don’t castrate them if you don’t need to and if you have a good market for them.
  • On large farms the risks of stray ram lambs disappearing and turning up again to mate ewes before they are discovered is a real one, so castrating all unwanted males is sound management.
  • It’s recommended that castration should be done after maternal bonding has been completed (i.e. 12-24 hours) and before 6 weeks of age.
  • Under current law it is an offence to castrate any sheep over 9 months old unless it is done by a veterinarian who will use some form of anaesthetic.
Rubber rings
  • Using rubber rings is the most humane method.
  • A ring is stretched with special pliers and placed around the neck of the scrotum.
  • The rule is simple – make sure that before the ring is released that both testicles are below the ring and the rudimentary teats are above it.
  • Hold the testicles down with your free hand in the scrotum while you release the ring to make sure they don’t escape back above the ring.
  • It’s best to do the lambs between 7-10 days old.
  • Lambs feel pain as judged by them lying down and kicking from 5-15 minutes but then they show no more obvious distress.
Two nicely docked lambs. Tails will drop off in about 10 days. They are marked on the tail to help check on mothering up
  • This used to be the standard method before rubber rings were invented.
  • It is not recommended now because it’s slow and the risks of infection, bleeding from the wound, hernias and blowfly attack is very possible.
  • The bottom of the scrotum is cut with a sharp knife or scalpel and the testicles pulled out or “drawn”.
  • They are slippery and hard to hold and pull out. Old shepherds used to draw them with their teeth!
  • Research has shown it is much more painful than the rubber ring method.
  • Surgical castration should only be done by a veterinarian using pain control.

Emasculator pliers
  • These pliers (called the Burdizzo emasculatome) crush the spermatic cords making the ram infertile.
  • They are slow and clumsy and are not used much now.
  • There is always doubt about the result too as you cannot see the end result of the action.
The cryptorchid procedure
  • This is also called the “short scrotum method” and is where a rubber ring is put around the scrotum so it will eventually drop off, leaving the testicles up against the body wall.
  • The higher temperature this creates makes the sperm infertile while the ram gets the growth benefit of the male hormones while being infertile.
  • Be warned though – an odd cryptorchid may not be completely infertile and may be able to get females pregnant.

Tail docking
At what age?
  • The minimum standard says tail docking must only be done if there is a significant risk of faecal or urine contamination, or blowfly strike that will lead to poor hygiene and health. So if you cannot justify it – then don’t do it.
  • Without pain relief - dock lambs as young as possible, and not older than 6 months of age.
  • Beyond 6 months you must use pain relief which may mean the costs of a veterinarian.
  • Generally docking should be done after maternal bonding has been completed (i.e. 12-24 hours). But some farmers dock with rubber rings when tagging the lambs and claim it does not affect bonding.

What length to leave the dock?

  • The tail dock (the bit left) should be long enough to wag!
  • A good guide is that the dock should cover the vulva of a ewe lamb and be the equivalent length in males down to the bald bit on the underside of the tail. This is clearly stated in the MAF Sheep Code of Practice.
  • If the lamb is able to raise it’s dock when defaecating, it lifts the supporting tissue around the anus (the caudal folds) so can direct any diarrhoea which is common on New Zealand pastures away from the body.
  • If the dock is too short, the dung runs down its legs and into it’s crutch.
  • Leave the tail on any ram lamb that you cannot locate the testicles – it’s a good visual sign when drafting. It’s a ‘long tailer” and hence a cull.
This ram's tail dock is far too short, and you can see
the damage done to the tail ligaments. The
MAF Sheep Code of Welfare has been ignored

Rubber rings
  • Use rubber rings when lambs are 7-10 days old, and the tail should drop off 10-14 days later.
  • Don’t cut the tail off below the ring as the blood can attract blowflies.
  • Check the scar on the tail stump incase it has gone septic and attracts blowflies. This does not often happen.
  • Here a gas-heated iron is used to both cut and cauterise the tail in one action.
  • Correct pressure on the iron is important to make sure the stump has been cauterised during the cutting action. A steady slow action is needed.
  • You soon learn to get it right if you have to hold a bleeding tail stump between your fingers, and cauterise it with the hot iron while the lamb is kicking with the pain!
  • Check that no docks are bleeding before returning lambs to their mothers. Any that are bleeding will have to be re cauterised.
  • Blowfly repellant can be applied to the dock if flystrike is a problem.
  • Don’t dip the lamb’s backside in a drum of sheep dip as the fluid rapidly becomes contaminated with blood and dung over time and does more harm than good.
  • This was the old method but has been shown to be much more painful than rubber rings and it should not be used.
  • The blood from newly-cut tail docks only attracts blowflies.
General comments on docking

  • Only dock lambs on dry days and try to keep the docking area clean. This is easy when lambs are docked in the paddocks they were born in, but if done in the regular sheep yards is often more difficult.
  • Keep the equipment clean by occasionally washing with disinfectant.
  • Operators should also try to keep their hands and overalls clean
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.

No comments:

Post a Comment