Mystery ingredients in cat food manage to throw off a scientific study

Researchers wanted to find out how much wildlife domestic cats eat to supplement the food they are given by their owners. But pet food manufacturers didn't make it easy.

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Alison DeNisco Rayome
2 min read

Turns out that cat food manufactures don't use the same type and amount of ingredients in every can. 


Most cat owners know that our furry friends eat not only the food we lovingly pour into their bowls, but some wild prey as well. Researchers from North Carolina State University wanted to learn how many extra wild "treats" our cats eat along with their regular wet or dry food, but getting to that answer was more difficult than expected thanks to something many cat owners have long suspected: Cat food manufacturers don't use the same type and amount of ingredients in every bag, even when food is the same brand and flavor, their research showed.

In a paper published last month in the journal PeerJ, the researchers examined isotopes from things a cat might eat, including different brands and flavors of cat food. They predicted that cats would have an identical isotopic match to the food they eat, and any differences would indicate that a cat was supplementing its diet with wild prey. But it turns out that the isotopes in cat foods varied widely, even among the same brands and flavors. They did find one thing: The least expensive cat foods had higher carbon values, which suggests more corn product. 

"This isn't what we aimed to study, but it is important in as much as there are hundreds of millions of cats (perhaps more) on Earth," Rob Dunn, co-author of the study and a professor in NC State's Department of Applied Ecology, said in a press release Friday. "The diets of cats, dogs and domestic animals have enormous consequences for global sustainability, cat health and much else. But they are very non-transparent. In short, at the end of this study we are still ignorant about why some cats kill more wildlife than others, and we have also found we are ignorant about something else, the shifting dynamics of 'Big Pet Food.'"

Watch this: Going paws-on with a robotic cat that listens to your commands (sometimes)