How sheep breeding could offer best chance for flystrike control

Sheep that are not susceptible to flystrike could be the long-term solution to a big industry problem.

BREEDING strategies could be the only long-term solution to flystrike management and producers should be thinking about this when making ram selections.

Dr Mark Ferguson said rising resistance to a range of chemicals used to try to control flystrike should encourage producers to think laterally.

Dr Ferguson heads up Nextgen Agri, a consultancy based in New Zealand, which does extensive work across Australia with ram breeders and commercial sheep operations.

“Breeding sheep that are not susceptible to flystrike is the only long-term solution to flystrike,” Dr Ferguson said.

“One by one, our preventive chemicals are dropping – like flies.

“Chemical resistance starts out by reducing the amount of time the chemical provides protection for and eventually the chemicals do not work at all.”

And while rotating chemicals and integrated pest management helps, Dr Ferguson said the less susceptible sheep were to flystrike, the less breeding grounds there were for the sheep blowfly.

He said there were a number of traits which influence breech strike, including dag, breech wrinkle, urine stain, breech cover and wool colour, which had varying levels of heritability.

And in Merino sheep, reducing breech wrinkle was “a critical step in reducing the susceptibility of your sheep to breech strike”.

Dr Ferguson said there were key characteristics that should be sought when buying rams with flystrike control in mind.

“The ram team is the best weapon in the fight against breech strike,” he said.

In terms of selection, Dr Ferguson said rams should have:

NEGATIVE breeding values for dag score. If this is not possible, ram buyers should ask for raw dag data for rams and compare this to the mob average. Worm egg count breeding values should also be needed.

NEGATIVE breeding values for breech wrinkle. If this is not possible, assess the ram for wrinkle but single born lambs will have more wrinkles than twins.

TRY to buy rams which are from ewes that have low urine stain scores, though these details are not routinely collected or recorded, and with low breeding values for breech cover.

WOOL colour is important as it is an indicator of body strike. Dr Ferguson said sheep with genetically white wool were less prone to both breech and body strike.

Dr Ferguson said it was not necessarily an easy process to breed sheep with a goal of low or zero levels of flystrike.

“Breeding towards a fly-free future means putting some serious effort into the traits that predispose animals to flystrike,” he said.

“Obviously selection for these traits needs to be balanced with selection of other production traits however for too long, we have selected animals for high performance at the cost of welfare outcomes or high chemical usage.

“It is high time that we balance this with selection for animals that naturally maintain a high level of welfare without requiring excessive chemical use.

“But the good news is that it is not all about trade offs as selection for lower wrinkle and bare points have a positive effect on reproduction.”

Dr Ferguson said ram selection was a significant opportunity to make rapid changes.