Spray raises medic copper test results

Elders Naracoorte agronomist Adam Hancock, working with the Grasslands Society of Southern Australia's Limestone Coast branch, said the goal more specifically was to increase copper levels in medic.

He said medic was generally low in copper, but its suitability to the region meant it was playing a large role in pasture mixes.

"We are seeing a lot more copper deficiency issues in the area, compared to a couple of decades ago," he said.

"We've got copper deficiency building up and more medic going in - it's a perfect storm. If we can lift the copper in medic, win-win."

Using Cavalier medic, sown on May 31 at 10 kilogram a hectare density, the trial compares a number of treatment options, including liquid injections below the seed, foliar applications and copper sulphate sprayed directly onto the soil.

While only in its first year, the trial already offered significant results, Mr Hancock said.

The control plot measured 3 milligrams of copper/kg of dry matter. The best plot measured 12mg/kg/DM.

That was the copper sulphate applied to the soil at 20kg/ha before seeding.

Mr Hancock suspected dropping back the application rate to 10kg/ha or even 5kg/ha would not decrease the results.

"Spraying can be quite a long-term solution," he said.

"You could spend $40/ha as a once-off fix and have it last 20 to 40 years and that does stack up."

This comes as research shows copper deficiency has the potential to hit lambing percentages by as much as 30 per cent, knowing the right method to prevent or treat the condition is key, according to AgriPartner Consulting's Hamish Dickson.

Speaking at the Grasslands Society of Southern Australia field day at Avenue Range, late last month, he shared the results of a three-year trial looking at copper deficiency in livestock.

Mr Dickson said copper was essential for body, bone and wool growth, pigmentation, healthy nerve fibres and in white blood cell formation.

"When we see deficiencies, we start to see immunity issues," he said.

"You might see stock dying from pneumonia after they were predisposed by copper deficiency."

Mr Dickson said a lot of the physical signs of deficiency, such as loss of pigmentation in coloured hair and wool or lameness in cattle, only became evident once the condition was severe. Fertility could also be affected.

"When severe deficiency was observed in western Vic, up to 30pc of ewes were not in lamb," he said.

But treatment reduced that by 20pc.

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Mr Dickson said there were four main ways to identify copper deficiency, but the value of these varied.

He said blood tests would generally only show deficiencies once the supply in the liver was exhausted.

Liver samples were the best indication but it was not always practical.

"If there is a glaring deficiency in soil type, it is likely to show in animals, but often it's not a direct correlation," he said. "Pasture samples tend to be much better indicator of animal health."

Mr Dickson said there was also two types of copper deficiency - the first caused by low levels of copper available and the second caused by levels of antagonistic minerals limiting absorption.

"Treatment for the two different scenarios should be different as well," he said.

He advised testing a paddock three times a year, with a representative sample.

"A pasture test gives quick, easy results and a broadspectrum look, showing other minerals and interactions," he said.

Most stock need copper levels to be between seven milligrams a kilogram of dry matter and 11mg/kgDM, but this can need to be higher if mineral molybdenum or another antogonistic mineral are present. Treatment options included loose licks, injections, water treatments and bolus or capsules.

"All treatments work but you need to know where deficiency sits to work out how much copper to throw at them," Mr Dickson said.

He warned copper could be toxic to livestock in high amounts, with crossbreds more susceptible than Merinos, so it was important to be sure there was a deficiency.