Going blind: fresh feed brings fresh animal health issues after drought breaks
Lush feed where the drought has broken has, counterintuitively, brought fresh animal health problems, including weight loss, milk fever and even blindness, a livestock nutritionist says.
Elders livestock production manager Rob Inglis, who is based in Wagga Wagga, said he had seen a surge in illnesses caused by nutritional deficiencies this spring.
“For example, one fellow down at Euroa weaned cattle onto what he thought was a beautiful oat crop, but they’ve actually lost a bit of weight,” Mr Inglis said.
Mr Inglis said pasture across much of south-eastern Australia was changing quickly, converting the sugars used for energy into undigestible, fibrous stalks.
A 10 per cent drop in digestibility could be the difference between putting on and losing weight.
“Be warned, in many cases this has occurred and stock, particularly production stock, have hit the wall,” Mr Inglis said.
“If you don’t believe me weigh stock on pasture now and then in again in a fortnight.”
It meant, he said, that even stock in paddocks with plenty of feed might need to be supplemented.
“It might seem ridiculous to supplement stock in a spring like this, but I guarantee those who start early will avoid a lot of pain later on,” Mr Inglis said.
“Every day stock lose weight adds three days to the finishing date, and time is money.”
Mineral deficiencies were also appearing. Mr Inglis said that while the lambing and calving seasons were largely over, he was still seeing cases of hypocalcaemia in pregnant, lactating and weaned stock.
Calcium levels had been depleted over the past two years of drought, he said, and the sheer bulk of feed in paddocks now was diluting many essential minerals. Zinc, selenium and copper deficiencies were also evident.
“I had a bloke from Bendigo this morning with calves on lush grass that are going blind,” Mr Inglis said.
“The cows are fat as pigs, but the calves are blind because they’re slightly zinc deficient and they can’t make sufficient vitamin A, which compromises their eye health.”
The performance of cows or ewes on a pasture could be misleading for producers, Mr Inglis said, because they had both lower requirements and larger rumens capable of digesting more feed than young stock.
“A young, growing animal needs good quality protein, as well as a suit of critical trace minerals. Most of the protein – up to 80pc – is a product of rumen fermentation, so optimum rumen function is essential for health and growth,” Mr Inglis said.
“They’re not getting that because, while the feed’s so vast in quantity, it’s quite low in quality and they just can’t eat enough to satisfy energy requirements.”
Mr Inglis said Elders livestock production advisors across the eastern states were advising clients to weigh stock less than 12 months old monthly.
If growth rates plateaued, he recommended testing the feed value of pastures to determine which nutrients were limiting so a nutrient budget could be devised. Blood tests for selenium, copper, and vitamin B12 would also help identify deficiencies for some trace elements.
Mr Inglis said selenium was a powerful antioxidant and deficiencies would compromise immune systems, stifling growth. Vitamin A, which requires adequate zinc in the diet, was needed for mucous membrane health, including eyes, lungs, reproduction and gut function.
“Particularly in some of the cropping country that’s been heavily cropped and heavily fertilised, we are seeing zinc deficiencies,” he said.
After testing feed and stock, Mr Inglis said, it was important to supplement accordingly and consider injections to replenish trace elements.
“It’s great to see so much feed around but keep an eye on your stock to make sure they’re growing as they should, and if you see that slowing, talk to an Elders livestock production about adjusting diets or finding another way to top up nutrients and minerals,” he said.