Why We Lab Test Cat Food

At Cats.com, we’re proud to be the only cat food review publisher that regularly submits cat food samples to an independent lab and shares in-depth reports on each food’s nutritional composition and any contaminants.

Lab testing costs a lot of money and takes a lot of time. So why don’t we just rely on the guaranteed analysis and information from the manufacturer?

Here’s why lab testing is so important.

We shouldn’t have to submit foods to a lab to get basic information about the nutrition and safety of our cats’ diets, but we do.

Lab testing is often the only way to know the real nutrient composition of a cat food.

The guaranteed analysis gives you a general picture of how much protein, fat, fiber, and moisture is in the food. But it’s far from perfect.

Most importantly, the guaranteed analysis is a set of minimum and maximum values. It tells you what the food is guaranteed to contain, not what it actually contains. That’s a big problem, especially when you’re trying to calculate the food’s carbohydrate content.

By sending the samples to a lab, we’re able to find out exactly how much of each key nutrient is in a particular recipe. Instead of believing that a food is at least 40% protein, we know that it’s 53% protein. Instead of estimating that it’s about 10% carbohydrates, we know that it’s 15% carbohydrate matter.

It might seem like a small discrepancy, but those numbers make a big difference to our cats.

Secondly, lab testing identifies potentially-harmful contaminants.

Our lab tests look for metals like mercury, aluminum, and lead. These are virtually never mentioned on the cat food label, but they can affect your cat’s health.

Bacteria, mold, and yeast can make your cat sick, and an elevated presence in our lab reports indicate that these contaminants made it past the manufacturer’s quality control system and, potentially, into your cat’s bowl.

Finally, we test for phosphorus and sodium, which almost never appear on the label.

Because these minerals can affect the wellbeing of senior cats and those with kidney disease, it’s important to know how much is in your cat’s food. Instead of chasing after this information from the manufacturer, we request these values in every lab report.

Reading the Report

A laboratory’s full pet food analysis looks a bit different from the guaranteed analysis you’re used to reading on the label, so let’s learn a bit about how to read and interpret these reports.

The pet food analysis report contains several columns that tell us about each analyte (that’s a term referring to each component for which the chemists tested).

Moving left to right, the columns tell us:

• Which analyte we’re looking at in the row, e.g. “Yeast”
• The result, which is the concentration of the analyte found in the sample
• The minimum determining limit, which is how much of the analyte must be present before the test is able to measure and it with 99% confidence
• The reporting limit, which is the smallest concentration of a substance that the lab can report
• The units in which the reported result is measured, e.g. CFU per gram or milligrams per 100 grams
• The date on which the analysis was completed
• The method the laboratory used to complete the analysis, e.g. FDA-BAM, 8th ed, Ch 3 (click to see FDA documentation on this testing method)
• Any qualifiers, e.g. problems or irregularities affecting the results

Interpreting the Report

Now we know what the report is telling us, but how do we interpret these data? Let’s walk through the various substances in each report and what the results mean.

Aerobic Plate Count, APC

As a generic test measuring the bacterial population of a food sample, the aerobic plate count (APC) is a rough indicator of the food’s safety. Lower values generally suggest that the food is sanitary and contains lower populations of potentially-pathogenic bacteria. For reference, values of 100,000 CFU/g are normal for fresh ground beef.

Yeast & Mold

This identifies the amount of yeast and mold in the food. High levels indicate potentially-harmful contamination.

Lead, Nickel, Zinc, Aluminum, Arsenic, & Mercury

These elements are sometimes found in cat food, primarily due to bioaccumulation in protein sources. Plant-based ingredients, including wheat, peas, barley, and corn, also accumulate toxic metals and metalloids from the soil in which they’re grown.

Cyanide

This toxic compound is sometimes seen in cat food, most likely due to the presence of ingredients with cyanogenic glycosides.

Ash

Ash is what would remain if all the organic compounds in the food were burned off, leaving behind only inorganic compounds (like calcium, magnesium, phosphorus, potassium, sodium, silicon, sulfur, and other trace minerals).

Lower-ash foods may be sought to help a cat with recurring urinary tract issues or kidney disease. Normal ash content in a cat food is between 5% and 8%.

Protein (crude)

This identifies the amount of protein in the food, not accounting for bioavailability. AAFCO guidelines require that cat foods meet a minimum of 30.0% protein content for growth and reproduction and 26.0% for adult maintenance. No upper limit has been established.

Total Carbohydrates

This identifies the amount of carbohydrate matter in the food. Carbohydrate matter is not nutritionally necessary for cats, and there is no minimum requirement for carbohydrates in cat food. At Cats.com, we recommend choosing a diet with less than 10% carbohydrates on a dry matter basis.

Fat (crude)

This identifies the fat content of the food, not accounting for bioavailability. AAFCO has established a minimum requirement of 9.0% fat for growth and reproduction and 9.0% for adult maintenance. It has not established a maximum fat limit for cat food.

Fiber (crude)

This identifies the amount of fiber (indigestible carbohydrate matter) in the food. AAFCO has not established minimum or maximum levels of fiber for cat food, but fiber content between 2% and 8% is normal.

Moisture

This identifies the amount of moisture (water) in the cat food. The amount of water in the food varies depending on the processing method, and no minimum or maximum limit has been established by any authority.

Phosphorus

This identifies the amount of phosphorus in the food. AAFCO has not established an upper limit for phosphorus in cat food, but the minimum is 0.5% dry matter weight for adult maintenance and 0.8% dry matter weight for growth and reproduction.

Sodium

This identifies the amount of sodium in the food. AAFCO has established a minimum requirement of 0.2% sodium for growth and reproduction and 0.2% for adult maintenance.

AAFCO has not established a maximum upper limit, but the National Research Council (NRC) puts the safe upper limit of sodium in feline diets at 740 mg/mJ (megajoule) of metabolizable energy (ME), or 1.25 g/kg in 4000 kcal ME/kg diets). A controlled-sodium diet may be advisable for cats with kidney disease.

We’re challenging the cat food industry to do better.

By going beyond the guaranteed analysis, publicizing the impurities found in cat food, and sharing information on components, like phosphorus and sodium, that seldom show up on the label, we hope to encourage brands to establish clearer standards and share this vital data with their customers.

For now, we’ll continue sharing this independent data and helping you to make better choices for your cat. Thank you for helping us make the world a better place for cats!

Disclaimer: Occasionally, we may supply lab reports and product chemical and ingredient analyses as part of a product or brand review. Such reports are provided by 3rd party analysis service providers and are intended for informational purposes only. Any liability arising from the accuracy and comprehensibility of such lab analyses will be under 3rd party service provider’s sole responsibility.