Looking beneath the wool: Analysing Merino skin for genetic improvement

Pepper Well Poll Merino stud principal Hansi Graetz, Keyneton, SA, said he first became interested in understanding breeding plain-bodied sheep after attending a workshop at a university in 1993.

"[The expert] explained to us why we have good wool, average wool and better wool, and the science behind what's happening in the skin," he said.

"I went through all our ewes and I found three in 300 ewes that were vaguely heading in that direction of quality wool."

Mr Graetz focused on changing his flock and stopped mulesing below the tail in 2007.

He now manages a flock of about 700 breeding ewes.

"The real challenge when you go non-mules, more often than not your animals don't have high follicle density, they're dense because they have wrinkle," he said.

"If you breed the wrinkle off, you end up with skins with low-follicle density and you lose quite a bit of wool production."

Mr Graetz said he decided to take images of Merino flesh with a macro camera lens to show the difference between animal qualities, and help people understand the process of wool growth.

"It's so they can distinguish between a good animal and a bad animal when they're making their decisions," he said.

"The bad skin has very confused follicle depth, completely disorganised, all different angles and even crossing over.

"It leads to bad blood flow, which affects the nutrient uptake of the follicle and its ability to grow more fibre."

He said one of the main challenges when transitioning flocks was to keep follicle densities higher.

"In your first cross you're going to lose wool cut, and you end up with a plainer skin which is stiff and maybe 60 or 70 follicles per millimetre," he said.

"As you improve the skin, you end up with around 100 or even more follicles per millimetre."

Mr Graetz said his current focuses were to improve carcase, and fat levels with yearling fat and yearling muscle.

He said he hoped to see more farmers and researchers come forward with information about focusing on skin quality.

"It's an aspect that is overlooked by a lot of people, skin quality, they just look at the wool and the animal," he said.

"I believe people who have good knowledge of skin quality and the different types of skins, they will progress very quickly with the muscle and fat traits while keeping quality wool."

Mooralla Merino stud principal Ricky Luhrs, Mooralla, said they started to chase a modern Merino in 2011 and 2012, after hearing speakers at a BestWool BestLamb conference.

He said they introduced electronic identification tags to the flock in 2013, and focused on reducing dag and maintaining and improving fleece quality.

"Our main focus back then was to maintain fleece weight but increase staple length to a plainer body," he said.

He said he looked for an open fleece which can disperse moisture, and a bare breech wrinkle score to reduce any sweat glands for flies to lay eggs in.

"By noting wrinkle scores and following what got flies and what got less flies, we ceased mules in 2018 off the back of seeing what worked and what didn't work," he said.

"We're impressed with what we've seen, we now run a stud that's full pedigree and full genetics," he said.

"We've been measuring [wrinkle and dag] for the past five years and wool colour, our goal is basically to have a highly productive carcase focused merino in a high rainfall zone."

Mr Luhrs said he advised other farmers to be unafraid of bringing in new genetics, and understanding the progeny out of those genetics.

"One thing I've learnt is the environment is a massive player on genetics, what might work 100 kilometres away might not work at your place," he said.

Australian Wool Innovation research general manager Bridget Peachey said it was important to consider wool quality, conformation and breech traits - including wrinkle, dag, urine stain and cover - when dealing with flystrike.

"Sheep classing, selection and joining is the long-term solution to moving to a non-mulesed enterprise," she said.

"The traits listed above are the highest risk, well-researched, and those which growers can readily assess, measure, influence and monitor."

She said for Victorian producers, or farmers on winter-dominant pastures in southern Australia, up to 40 per cent of ewes had persistent scouring and severe dags from July to October.

Ms Peachey said more than 60pc had a substantial amount of soiled breech wool removed at crutching, due to low larvae and adult worms during summer, and a rapid build up during winter and spring.