TAIWAN – A recent DNA barcoding study has revealed that 40 of 138 products were mislabeled, a practice that can harm pets, violate pet owners’ religious dietary restrictions and negatively impact natural resource management.

The study used DNA barcoding methods to identify highly processed pet food species. The analysis revealed widespread misrepresentation of species, often involving the substitution of tuna with other fish species or including undeclared ingredients. The overall mislabeling rate was found to be 28.99%.

The study, conducted by researchers Yu-Chun Wang, Shih-Hui Liu, Hsuan Ching Ho, Hsiao-Yin Su, and Chia-Hao Chang, focused on a segment of the mitochondrial 16S rRNA gene as a barcode. 

They used Sanger or next-generation sequencing (NGS) to analyze the cat food contents, identifying the extent of species misrepresentation in Taiwan’s pet food market.

Of the 138 cans analyzed, the researchers identified 38 labeled ingredients, including various fish, poultry, livestock, reptiles, crustaceans, and mollusks. Out of these, 89 cans were correctly labeled, nine were uncertain, and 40 were mislabeled. 

The mislabeled products either contained species not listed on the label or omitted species that were present.

A notable finding was the frequent replacement of tuna with other Thunnini fish species. Only Thunnus and Katsuwonus species can legally be used for commercial tuna products worldwide, but the study found genera such as Auxis and Euthynnus being used instead.

The mislabeling rate of 28.99% suggests that the issue is more widespread than previously recognized. All products examined by NGS metabarcoding contained undeclared species, indicating extensive mislabeling in the Taiwanese market. 

Furthermore, nearly all fish identified in the samples were wild-caught, not farmed, highlighting concerns over resource exploitation.

The study also discovered an endangered shark species in one of the canned products, underscoring the need for more DNA barcoding projects. These efforts can help protect pet owners and their pets while providing crucial data for managing marine fishery resources.

Why mislabeling of pet food is a serious problem

Mislabeling pet food poses several risks. It can lead to consumers handling products that conflict with their religious, cultural, or medical restrictions. 

For instance, pig was not listed as an ingredient in any of the products tested, but the analysis identified it in some, which could be problematic for Muslim pet owners. Similarly, the detection of non-kosher shark species could concern Jewish pet owners.

Undeclared ingredients also pose health risks for pets with food allergies. The study highlighted the presence of undeclared beef and chicken in some products, which could trigger adverse reactions in sensitive cats.

The researchers called for more investigations into pet food labeling to protect pet health, prevent consumer deception, and ensure the sustainable use of fishery resources.

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