Breeding all rounders

Location: Walcha, NSW

Enterprise: Poll Merino and White Suffolk stud, commercial Merino flock and Angus herd

Producer: Martin Oppenheimer

Soil type: Sandy, grey loams, trap soil

Pasture type: Tall fescue, cocksfoot, phalaris, chicory, plantain, white and sub-clover

A holistic approach to worm control considering genetics, pasture management and nutrition can deliver huge benefits, says Poll Merino and White Suffolk seedstock producer Martin Oppenheimer. 

Having an occupation as a ‘holistic sheep designer’ may sound a bit ‘hippy’ but it accurately describes what Martin Oppenheimer does for a living. 

The Poll Merino and White Suffolk breeder, based near Walcha, NSW is intent on producing the best high-performance animals he can for his challenging highaltitude environment. 

He does this by achieving a delicate balance between genetics, nutrition and grazing management. 

“The art of genetics is getting the important traits in balance, particularly fibre diameter, staple strength and fleece weight with body weight, eye muscle and fat,” Martin said. 

“With Merinos there is a lot of genetic variation and therefore a lot of potential for improvement.” 

Martin is a fifth generation Merino breeder; his great, great grandfather registered a flock in 1868. ‘Petali’, the stud, was formed by his parents in 1966 and, through improved genetic selection, grazing management and trace element supplements (particularly selenium), Martin has transformed his enterprise from district average to benchmark leader. 

“We run Petali at 16DSE/ha, the district average is 11DSE/ha and the average number of worm treatments is five to six while ours is three,” he said. 

Side effects 

One of the keys to this success has been the stud’s continued selection for worm resistant sheep, which are sheep with negative yearling worm egg counts expressed as negative YWEC Australian Sheep Breeding Values. 

Worm resistance has positive correlations for carcase and production traits such as body weight, eye muscle and fat as well as weaner survival. 

All this has been achieved without sacrificing micron, with the flock average at 17.2 and most of the one-year-old sheep from 14 to 16. 

“When I first came home from university in 1980 we were drenching our sheep once a month. People in the district were suffering from organophosphate poisoning from drenching and dipping sheep so often and we were always looking to the next new chemical to save us from drench-resistance problems,” Martin said. 

“I was convinced there had to be a better way to do all this – what we were doing was unsustainable.” 

From the early 1990s, Petali sheep were selected for worm resistance, and within a decade the Oppenheimers have cut their drenching program back to once a year for wethers and three times a year for the rest of the flock. 

“Now, our main treatment is administered pre-lambing (ewes lamb off-shears in spring), we do another treatment at weaning and then another pre-joining,” Martin said. 

Wider take up 

Commercial producers have been quick to follow Petali’s lead with strong demand for rams with YWEC ASBVs of -50 to -60 and better. 

“At -60 they’re trait leaders in the top 10% of the breed,” Martin said. 

“It’s very difficult to sell rams now with positive YWECs. For some of our clients, who are from areas with particularly nasty strains of Barbers Pole, being able to source these trait-leading rams means being able to stay in business.” 

Martin said producers who have never used YWEC ASBVs as a selection criteria for their rams could still expect to make significant gains in flock performance within three to five years by selecting moderate to highly resistant rams. 

The rate of that improvement will depend on the ewe base as rams are only half of the genetics,” he said. 

Martin has made further improvements including breech and dag scores and aims to improve fertility and reproductive traits. 

“There’s a huge variation in ewe performance and we see a lot of potential for improvement, particularly in the number of lambs weaned and weaning weights,” he said. 

“Having worm-resistant sheep is not just a feel-good thing – it means we use fewer chemicals and have lower costs. It has also resulted in better animal welfare outcomes and healthier people.” 

Lessons learned

  • Worm resistance is moderately heritable and selection for the trait can significantly improve flocks within a few years.
  • Worm resistance has positive correlations with carcase traits such as eye muscle, fat and body weight as well as weaner survival.
  • Worm resistance and carcase traits can be improved without sacrificing micron.
  • Worm resistant sheep result in less reliance on chemicals, lower costs, better animal welfare outcomes and healthier people.
Walcha, NSW
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