Manitoba Agriculture is urging producers to test their feed after a harvest analysis report flagged greater risk of mycotoxin contamination in corn silage.
Early findings from the Alltech 2024 Canadian Harvest Analysis suggested plenty of variability in contamination levels across Canada, but there were particular concerns on corn silage quality, according to a Nov. 7 Alltech release.
“If producers are concerned with feed quality or mycotoxins, they should have their feed tested,” said Shawn Cabak, a forage and livestock specialist with Manitoba Agriculture, in an e-mail to the Co-operator Nov. 14.
Read Also
Shifting standards on cattle parasite control
Parasite product resistance has more farmers and veterinarians thinking differently about how to control issues like lice or worms.
Why it matters: Manitoba has plenty of feed, although early wet weather delayed hay cuts and experts urged producers to watch for quality concerns. That advice extends to annual feed crops.
Cattle have many potential menu options, including byproducts like dried distillers grains or otherwise wasted cast-offs from the grocery system. They can make good use of ammoniated low-quality forage.
It isn’t so much about type of feed, Cabak noted. It’s about making sure the ration is balanced and its ingredients are known.
“If producers know what toxins are present and at what levels, the rations can be adjusted so the feed can still be utilized at a safe/diluted rate,” he said.
Mycotoxins, toxic compounds produced by moulds and fungi, present serious risks to livestock health and performance. Cattle will eat less, grow less, gain less and may seem frequently sick, but won’t respond to antibiotic medications, according to a fact sheet put out by the Beef Cattle Research Council.
They’ll abort pregnancies, birth early or produce less milk after calving.
They may drool or pant like they’re suffering heat stress, or they can spike a fever or have bouts of bloody diarrhea. Their mouths may seem irritated, with reddened tissue, blisters or ulcers. Especially if the problem is ergot, they might show gangrene around ears, tails and feet, or come up lame. There may be convulsions or paralysis.
The same resource stresses that mycotoxins are a “hidden hazard” detectable only through lab testing.
Reynold Bergen, science director with the BCRC, also stressed the role of testing to avoid mycotoxin problems in the herd.
“This is something we communicate about on a seasonal basis … to make sure it’s top of mind for producers,” he said via email.
The Canadian Food Inspection Agency is also worried about carry over.
Even if a livestock species is tolerant to that mycotoxin, the agency’s regulatory guidance on the issue warns, they can bring those toxins into the human food system after slaughter.
Harvest results
Alltech noted a dramatic jump in mycotoxin prevalence in crops. The recent report said more than 95 per cent tested positive for at least one mycotoxin and multiples were often detected.
Multiple issues in the same harvest aren’t unusual. Mycotoxins rarely occur singularly under natural field conditions, the CFIA notes, and “more commonly a combination of contaminants will be found.”
If different contaminated crops are mixed into a single feed, the agency warned, the problem can compound.
“Canada has experienced a change in weather patterns from last year, particularly of note the greater rainfall across the Prairies,” said Alexandra Weaver, global technical support for Alltech, in the press release. “As a result, there appears to be greater mycotoxin risk in the Western Canada 2024 harvest than last year.”
Manitoba reported that 59 per cent of barley samples contained DON (deoxynivalenol), with levels up to 3,700 parts per billion. Corn silage in the province showed 100 per cent prevalence of zearalenone (ZEA), peaking at 1,118 ppb. DON was present in 64 per cent of corn silage samples, with a maximum concentration of 3,200 ppb.
Saskatchewan saw 88 per cent of barley silage samples test positive for ZEA, with 30 per cent also containing DON. T2-HT2 toxins were detected in 43 per cent of samples. While overall risk remains moderate, Alltech said, certain samples showed higher concentrations.
In Alberta, barley silage presented lower risks, with 22 per cent of samples positive for ZEA. However, corn silage showed 100 per cent prevalence of ZEA, with levels exceeding 700 ppb. DON, T-2 and HT-2 toxins were also found in the corn silage samples, indicating an elevated risk.
Alltech also pegged ongoing risks from DON and ZEA in Eastern Canada.
For Quebec, 90 per cent of corn silage samples tested positive for ZEA, with levels reaching as high as 1,369 ppb. DON was found in 68 per cent of samples, peaking at 6,782 ppb. T-2 and HT-2 toxins were less prevalent, found in 25 per cent of samples, but still pose a concern for livestock producers.
In Ontario, 63 per cent of wheat samples contained DON, while 45 per cent showed the presence of ZEA. Corn samples also showed DON contamination, with a maximum level surpassing four parts per million. That poses the greatest risk to swine and younger animals, the organization said.
British Columbia’s corn silage samples revealed a range of fusarium mycotoxins, including DON, T-2 and HT-2 toxins, ZEA and other emerging mycotoxins. While the average risk level for dairy cows was low to moderate, some samples exhibited higher concentrations of DON and T-2 and HT-2 toxins.
Overall, Alltech says early testing indicates corn silage is the highest-risk commodity for mycotoxin contamination across Canada. Additionally, barley appears to show a greater prevalence and concentration compared to wheat. Although corn grain testing is pending, producers should remain vigilant as corn is typically at risk for contamination, Alltech warned.
How much is safe?
The answer may be different depending on who in the industry you ask.
The CFIA puts recommended ZEA tolerances for cows at 10 ppm, but if the feed also has other mycotoxins, that number drops to 1.5 ppm. For pigs, the recommendations ranges from under one to under three ppm for gilts, but the “swine industry has voiced concern over levels of 0.25 – (five) in diets for sheep and pigs,” the agency said.
For DON, cattle and poultry diets should come in at or under five ppm for “grains and grain by-products destined for ruminating beef and feedlot cattle” older than four months or chickens. The CFIA adds that caveat that the contaminated feed shouldn’t make up more than half of the animal’s diet even if it meets those levels.
For pigs, young calves or any animal that’s lactating, levels are more strict. No more than one ppm of DON should be present, and the contaminated grain product shouldn’t make up more than 40 per cent of the diet.
The agency puts tolerances at 0.1 ppm of HT-2 toxin in cattle and poultry (0.025 ppm if it’s dairy cattle), and under one ppm for T-2 toxin for swine and poultry.
“Be aware that there is much debate in the industry about guidelines, and the bottom line is that it is not clearly known what levels of mycotoxin are acceptable for feed,” the BCRC warns. “There is considerable variation among species and the age of the animal are feeding can vary the results. More research needs to be done to further answer this question.” — With files from Alexis Stockford
