By Deb Maxwell, Operations Manager, ParaBoss
Should you stop ‘cold turkey’ or a little at a time? A more successful approach is to develop a breeding and management plan. It’ll include your criteria for culling sheep, selecting rams, managing dags, tail length, chemical treatments and timing of crutching and shearing.
Mulesing has been a mainstay for breech strike prevention for decades, and in combination with chemical treatments and management actions, the rate of breech strike in 2011 was as low as 3% of ewes and weaners. It’s understandable that farmers don’t want to sacrifice this level of control by stopping mulesing and risk chasing struck sheep for months.
The good news is that breech strike can be controlled without mulesing, but you need to consider what other approaches to use.
Breeding and management options
The key breeding elements to reduce flystrike in winter rainfall and Mediterranean regions are to reduce dags and breech wrinkle with dags of most importance. In summer rainfall regions, reducing breech wrinkle is most effective.
The key management elements to reduce flystrike are to dock tails to a length equal to the tip of the vulva—certainly don’t butt tails, which only increase dags and urine stain and breech strike; have a good worm control plan to reduce dags; and time shearing, crutching and treatments to gain maximum benefit.
Making a start
Personally, I’m very big on trying things out in a small way and gaining confidence that I can deal with the results of a change. Here’s one way to give it a go.
Look up the visual scores for breech wrinkle on FlyBoss, which shows lambs from score one (very plain/no wrinkle) to score 5 (very wrinkly). Get a feel for each score.
Before lamb marking, get 50 extra ear tags that will stand out next to your other tags. As the lambs come over the cradle, score them for breech wrinkle (or ask the contractor to do so) and don’t mules 25 plain lambs (score 1 or score 2). Give these the extra tag so you can keep an eye on them. Cut a notch out of the remaining 25 tags and give these to lambs also with breech wrinkle scores of 1 or 2, but which were mulesed.
If you are very risk averse, choose just wether lambs for this trial, but ideally, have a go with ewe lambs so you can see what happens as they get older.
If you are in a winter rainfall region, you can do a similar exercise, but based on dag score at weaning.
Unmulesed breech wrinkle score 1 and 2 sheep have a very low chance of getting struck, but the occasional score 3 sheep might, and certainly quite a few more of the score 4 and 5 sheep. You may need to review your crutching and treatment times, and you can give the FlyBoss tools a go, which can compare and optimise your management and treatment times.
When all goes well, consider not mulesing more of the score 1 and 2 sheep and this success should provide incentive to choose plainer rams and to cull the wrinkliest ewes, so that gradually, your lambs become plainer.
Some studs also offer ASBVs for breech wrinkle, dags and breech cover on their rams, and importantly, there are plenty of highly productive plain rams; plainness does not have to mean lower fleece weight.
AWI R&D Update
AWI's National Wool Research and Development (R&D) Technical Update on Breech Flystrike Prevention was held last week. It’s worth visiting the web site just to see the amazing close up of the blowfly. While you are there, view the presentations, which include updates on breeding, genomics of both the fly and the sheep, mulesing alternatives, pain relief, survey results and the effect of mulesing status on wool price.