Rain sprouts toxic risks for livestock throughout stubble paddocks

Elders senior livestock production specialist, Rob Inglis, Wagga Wagga, said weeds such as hairy panic and heliotrope were a concern this time of year, along with other potential toxins such as nitrate poisoning and lupinosis for both sheep and cattle.

"I think the two main ones are hairy panic and heliotrope," Mr Inglis said.

"Both of them are highly unpalatable, particularly heliotrope, it's one of those weeds, they'll only eat it if they are starving, but if they are starving and start to eat it, the alkaloids will cause significant damage.

"People assume that it's copper poisoning, but it's actually the liver that gets so compromised, the liver releases a whole lot of copper and that's why they get that jaundice effect."

Effects of liver damage could be seen as quickly as a week to 10 days, he said.

Lupinosis was another toxin to keep in mind and there had been cases over the last few years, he said.

"When we get that continual humid, constantly showery weather, it's ideal for the formation of the phomopsis fungus," Mr Inglis said.

"I would suspect that there would be some lupin stubbles that you would be wanting to be very careful about.

"I still tell clients, monitor the stubble. If you have more than 100 kilograms of seed on the ground per hectare of unharvested seed, graze it, when it gets down to about 30kg of seed per hectare, you probably need to get the sheep off, because there's probably not enough there, they will start to eat the stubble."

The lupin seed itself was safe for stock but the stubble could contain the fungus, he said.

Stock would only eat poisonous weeds if they were starving and the best way to avoid this was to provide alternate nutrition, such as hay.

Mr Inglis said stock constantly gathering around hay or in alternate pastures was an indicator that there was little value in the available stubble.

Some stubble had been testing at up to eight megajoules of metabolisable energy prior to the recent rains, he said, but much of the goodness would have now been washed out.

He expected stubble would now be sitting at about 5MJ, and sheep would not be able to consume enough to maintain body condition.

"What's in the stubble itself would be of little value, you'd have to be supplementary feeding," he said.

"I would say if you're stocking at three dry sheep equivalent, they would have any residual grain cleaned up in a week or 10 days."

Another risk for livestock was nitrate poisoning where there was fresh growth appearing, he warned.

"It doesn't always mean in dead animals but they can be severely sick, nitrate can make them quite sick and scour and they will lose weight," Mr Inglis said.

"The worst case scenario is that you will kill them with nitrate poisoning, but the best case is the nitrate overload will cause some significant weight loss."

Stock going from dry feed to lush green pastures, such as canola or fresh lucerne, should be given a buffer such as hay to allow the rumen to adjust. Vaccinating for pulpy kidney was another management tool, Mr Inglis said.

Ewes should also be supplemented with calcium this time of year, he said.

"We're trying to build their calcium levels up over summer for an autumn or winter lambing. Cows with calves at foot too, they would be requiring some sort of calcium," Mr Inglis said.

"There are a few supplements that claim to have toxin binders in them, those toxin binders are actually designed to bind mycotoxins from moulds, they are less effective against alkaloids, so I think you have to be mindful of that."

Keeping track of body condition scores could ensure producers stayed on top of any issues, he said.

Uranquinty-based producers Trevor, Brenda and James Peterson, Killearn Agriculture, run a mixed-farming operation, with 8000 Lambpro Maternal Composite ewes and predominantly wheat and canola crops on 4000 hectares.

Trevor Peterson said ewes on stubble were fed salt and lime supplements, as well as StockMins-Detox, to help prevent the effect of the toxins, especially hairy panic.

Mr Peterson said the combination had significantly reduced fatalities due to hairy panic.

The family also slow the progression of toxic weeds by spraying the paddocks.

"While we're harvesting we move the sheep in as quick as we can," Mr Peterson said.

"Now James is coming round to start spraying so I have to move the sheep onto other stubbles.

"The spray machine comes in either just after the sheep have had the best out of it or before the sheep get in there, and then we go through the withhold and put the sheep in afterwards."

"Our lambs and even our ewes, if they are going to get a major dietary change, we will vaccinate them for pulpy kidney."