Story by Samantha Beattie, a member of the SPARK program (Students Promoting Awareness of Research Knowledge)

Prof. Trevor Smith
Prof. Trevor Smith

Pet food protein is changing, as traditional sources, such as fish and meat byproducts are replaced with plant-derived proteins. These proteins are more accessible and affordable, but they may be accompanied by harmful plant-based toxins, say University of Guelph researchers.

The toxins, known as mycotoxins, originate from fungi that grow naturally alongside crops in pre-harvest fields. Animals can tolerate some exposure, but mycotoxins may cause a loss of appetite, sleepiness, lack of co-ordination, immune system suppression and vomiting.

“A shift in pet food ingredients is on,” says Animal and Poultry Science professor Trevor Smith, who, after 35 years of mycotoxin research at Guelph, is a world leader in the field. “Instead of worrying about bacteria spoilage or disease contamination, like we have in the past, we now have to focus on removing mycotoxins.”

Smith says pet owners can help prevent their dogs or cats from consuming mycotoxins by avoiding cheaper pet food that is more likely to contain vegetable cereals and corn or wheat fillers. He particularly urges pet owners to avoid food with significant amounts of rice bran.

“That’s the ingredient that’s often contaminated,” he says. “Although we have no exact numbers, we can estimate that when half of the food is of vegetable origin, there will almost always be some degree of contamination. If the food is mainly of animal origins, the chances of contamination are greatly reduced.”

A common and symptom-triggering mycotoxin found in some grain-based dog and cat food is called deoxynivalenol (DON). Manufacturers screen for DON using enzyme-linked immunosorbent assay (ELISA) test kits, but they can detect only one chemical form.

Smith has found that DON sometimes changes structure when modified by plant enzymes. Although these DON compounds are just as toxic, screening tools were not available – until now. Smith found that by adding trifluoromethanesulfonic acid to the ELISA test, manufacturers could detect masked-DON compounds and remove the contaminated grains.

Because manufacturers readily use ELISA – and adding acid to the test is relatively affordable and simple – Smith says this approach may be widely adopted soon.

Another possible way to detect mycotoxins is to add yeast to pet food. The yeast’s fibre binds to the toxic molecules, Smith says, blocking DON from the blood stream and preventing negative symptoms.

Smith is also examining the effects of mycotoxin contamination in livestock feeds and how it influences pig, horse, cow and chicken behaviour. His ongoing goal is to improve animal welfare and health – mycotoxin contamination costs the livestock industry millions of dollars annually in lost revenues.

Collaborating with Smith is Animal and Poultry Science postdoctoral fellow Si-Trung Tran and graduate student Maureen Crump.

Funding is provided by the Ontario Ministry of Agriculture and Food, the Ministry of Rural Affairs and Alltech Canada, headquartered in Guelph.