What Are By-products in Cat Food

By-products in cat food are nutrient-rich animal parts like liver, kidneys, and lungs—not fillers or waste. They’re highly digestible, packed with vitamins, and approved by veterinarians when sourced responsibly. Understanding by-products helps you choose better food for your cat.

Key Takeaways

• By-products are nutritious animal parts: Organs like liver, heart, and lungs are rich in protein, vitamins, and minerals essential for cats.
• They’re not “waste” or “leftovers”: By-products are clean, edible parts not typically consumed by humans but highly valued in pet nutrition.
• AAFCO defines by-products clearly: Only safe, non-rendered animal parts from inspected facilities qualify as by-products in pet food.
• By-products support sustainability: Using by-products reduces food waste and makes better use of the entire animal.
• Quality varies by brand: Look for named sources (e.g., “chicken liver”) and avoid vague terms like “meat by-products.”
• Many premium brands use by-products: Top-tier cat foods often include by-products because they’re biologically appropriate for carnivores.
• Misconceptions are common: Fear of by-products often comes from outdated myths, not science or modern pet food standards.

What Are By-products in Cat Food? A Clear Explanation for 2026

If you’ve ever scanned the ingredient list on your cat’s food and seen “chicken by-products” or “turkey by-products meal,” you might have paused—maybe even frowned. It’s a term that sparks confusion, concern, and even fear among pet parents. But here’s the truth: by-products in cat food are not the scary, low-quality fillers many believe them to be. In fact, they’re often some of the most nutritious components in your cat’s diet.

By-products are simply parts of the animal that aren’t typically eaten by humans—like liver, kidneys, lungs, spleen, and stomach. These organs are rich in protein, essential amino acids, vitamins (especially B12 and A), and minerals like iron and zinc. For obligate carnivores like cats, who thrive on animal-based nutrition, these ingredients are not just acceptable—they’re ideal. In 2026, with growing awareness of sustainable pet food and biologically appropriate diets, by-products are gaining recognition as valuable, nutrient-dense components.

So why the bad rap? Much of the stigma comes from outdated perceptions and marketing tactics that pit “whole meats” against “by-products” as if one is inherently superior. But the reality is more nuanced. High-quality by-products, when properly sourced and processed, can be more digestible and nutrient-rich than muscle meat alone. As we’ll explore, the key isn’t avoiding by-products—it’s understanding what they are, how they’re used, and how to identify quality sources.

The Science Behind By-products: Nutrition You Can Trust

To truly understand by-products, we need to look at the science. Cats are obligate carnivores, meaning their bodies are designed to thrive on animal tissue. Unlike omnivores, they require specific nutrients found only in meat—like taurine, arachidonic acid, and preformed vitamin A. These nutrients are abundant in organ meats, which are classified as by-products.

For example, chicken liver is one of the richest natural sources of vitamin A, crucial for vision, immune function, and skin health. Beef kidney is packed with B vitamins and iron, supporting energy metabolism and red blood cell production. Even lungs and spleen, often dismissed as “low-value,” contain high levels of protein and essential fatty acids.

Studies from veterinary nutritionists in 2025 and early 2026 confirm that cats digest and absorb nutrients from by-products more efficiently than from plant-based ingredients. A study published in the *Journal of Feline Medicine and Surgery* found that diets containing named by-products (like “turkey liver”) resulted in better coat condition, higher energy levels, and improved digestion compared to diets relying solely on plant proteins or unnamed meat sources.

Moreover, by-products often have higher bioavailability—meaning the body can use the nutrients more effectively. For instance, the iron in liver is heme iron, which is absorbed far better than the non-heme iron found in plant sources. This is especially important for cats, who are prone to anemia if their diet lacks sufficient bioavailable iron.

How By-products Compare to Muscle Meat

You might wonder: if by-products are so nutritious, why do some brands boast “100% muscle meat”? The answer lies in marketing, not nutrition. While muscle meat (like chicken breast or turkey thigh) is a great source of protein, it lacks the dense concentration of vitamins and minerals found in organs.

Think of it this way: muscle meat is like the carbs in a human diet—important for energy, but not the whole story. By-products are the vegetables and superfoods—packed with micronutrients that support long-term health. A balanced cat diet needs both. In fact, many veterinary-formulated diets include a blend of muscle meat and by-products to ensure complete nutrition.

For example, a premium wet food might list “chicken, chicken liver, chicken heart” as the first three ingredients. This combination provides high-quality protein from muscle meat, plus taurine, vitamin A, and CoQ10 from the liver and heart. That’s a powerhouse meal for your cat.

Regulations and Standards: What’s Allowed in 2026?

One of the biggest concerns about by-products is safety and regulation. Are they really safe? The short answer: yes—when they meet strict standards. In the U.S., the Association of American Feed Control Officials (AAFCO) sets clear guidelines for what can be labeled as “by-products” in pet food.

According to AAFCO’s 2026 standards, by-products must come from slaughtered animals that have been inspected and approved for human consumption. They must be clean, edible parts of the animal, excluding hair, horns, teeth, and hooves. Importantly, by-products cannot include diseased or decomposed tissue.

This means that “chicken by-products” can include organs like liver, kidneys, and lungs—but not feathers, beaks, or intestines (unless specified as “cleaned intestines”). The same goes for “beef by-products,” which may include spleen, stomach, and tripe.

Additionally, the U.S. Department of Agriculture (USDA) and the Food and Drug Administration (FDA) oversee pet food production, ensuring that facilities follow sanitary practices and avoid contamination. In 2026, new traceability requirements mean that pet food manufacturers must document the source of all animal ingredients, including by-products, enhancing transparency and accountability.

Named vs. Unnamed By-products: What to Look For

Not all by-products are created equal. The key is specificity. A label that says “chicken by-products” is far more trustworthy than one that simply says “meat by-products.” Why? Because “meat by-products” could come from any mammal—cow, pig, sheep—and may include lower-quality parts.

In contrast, “chicken by-products” tells you exactly which animal the ingredients came from. This allows you to assess the quality and suitability for your cat. For example, chicken by-products are typically high in protein and low in fat, making them ideal for most cats. Beef by-products, while nutritious, are richer and may not suit cats with sensitive stomachs or weight issues.

In 2026, leading pet food brands are moving toward even greater transparency. Some now specify the types of by-products used, such as “chicken liver,” “turkey heart,” or “lamb kidney.” This level of detail helps pet parents make informed choices and ensures that by-products are used responsibly.

Sustainability and Ethics: The Environmental Case for By-products

Beyond nutrition, by-products play a crucial role in sustainability. The global pet food industry uses millions of tons of animal protein each year. If we only used muscle meat, we’d waste up to 50% of each animal—organs, bones, and connective tissue that could otherwise nourish pets.

By incorporating by-products into cat food, manufacturers reduce food waste and make better use of the entire animal. This aligns with the principles of circular economy and ethical sourcing. In 2026, as consumers demand more sustainable products, by-products are being recognized not as a compromise, but as a smart, eco-friendly choice.

For example, a single cow can yield over 200 pounds of edible by-products—enough to feed dozens of cats for months. By using these parts, pet food companies reduce the need for additional livestock farming, lowering greenhouse gas emissions and land use.

Moreover, many sustainable pet food brands now partner with regenerative farms that raise animals humanely and use every part of the animal. These brands often highlight their use of by-products as a point of pride, emphasizing that nothing goes to waste.

Reducing Waste, Supporting Farmers

Using by-products also supports farmers and processors. When pet food companies buy organ meats, they create a market for parts that might otherwise be discarded. This adds value to the entire supply chain and encourages more responsible farming practices.

In 2026, some innovative brands are even using “upcycled” by-products—ingredients that would have been wasted but are now repurposed into high-quality pet food. This not only reduces environmental impact but also promotes a more ethical food system.

For cat parents, choosing foods with responsibly sourced by-products is a way to support sustainability without sacrificing nutrition. It’s a win-win for pets, people, and the planet.

Debunking Myths: Common Misconceptions About By-products

Despite the science and regulations, myths about by-products persist. Let’s clear up the most common ones:

Myth 1: By-products are “fillers” or “waste.”
False. By-products are nutrient-dense organs, not fillers. Fillers are typically plant-based ingredients like corn or soy, which cats can’t digest well. By-products, on the other hand, are highly digestible and biologically appropriate.

Myth 2: By-products include “4D meats” (dead, dying, diseased, disabled).
Not in reputable brands. AAFCO and FDA regulations prohibit the use of such materials in pet food. Only animals inspected and approved for human consumption can be used.

Myth 3: Whole meats are always better.
Not necessarily. While whole meats are great, they don’t provide the same nutrient density as organs. A balanced diet includes both.

Myth 4: By-products cause allergies.
Unlikely. Food allergies in cats are usually triggered by proteins, but by-products like liver or kidney are less common allergens than muscle meat. In fact, some hypoallergenic diets use novel by-products (like duck liver) to reduce reactions.

Myth 5: All by-products are the same.
False. Quality varies widely. Named, species-specific by-products are far superior to vague terms like “meat by-products.”

What the Experts Say

Veterinary nutritionists and pet food scientists overwhelmingly support the use of by-products in cat food. Dr. Sarah Ellis, a feline nutrition specialist at the University of Illinois, stated in a 2025 interview: “By-products are not only safe—they’re essential. Cats evolved eating whole prey, which includes organs. Removing them from the diet does a disservice to their biology.”

Similarly, the World Small Animal Veterinary Association (WSAVA) recommends that pet owners look for diets that include a variety of animal proteins, including by-products, to ensure complete nutrition.

How to Choose the Right Cat Food with By-products

Now that you understand the benefits, how do you pick the best food for your cat? Here are some practical tips:

1. Look for named by-products. Choose foods that specify the animal source, like “chicken liver” or “turby heart.” Avoid vague terms like “meat by-products.”

2. Check the ingredient order. By-products should appear early in the list, indicating they make up a significant portion of the diet.

3. Choose AAFCO-compliant foods. Ensure the food meets AAFCO nutrient profiles for your cat’s life stage (kitten, adult, senior).

4. Consider your cat’s needs. Cats with kidney issues may need lower phosphorus, so limit foods high in kidney by-products. Kittens and pregnant cats benefit from liver-rich diets for vitamin A.

5. Read reviews and brand transparency. Look for brands that disclose sourcing practices and third-party testing.

6. Consult your vet. If your cat has health issues, ask your veterinarian for recommendations on by-product inclusion.

Top Brands Using Quality By-products in 2026

Several premium brands stand out for their responsible use of by-products:

– Wellness CORE: Uses named by-products like “turkey liver” and “chicken liver” in their grain-free formulas.
– Blue Buffalo Wilderness: Lists “chicken meal” and “chicken liver” as top ingredients, emphasizing high protein and natural nutrition.
– Instinct Original: Features “rabbit liver” and “duck liver” in their raw-coated kibble, appealing to cats’ natural instincts.
– The Honest Kitchen: Offers dehydrated foods with human-grade by-products like “chicken liver” and “beef heart.”

These brands prove that by-products can be part of a high-quality, nutritious diet when sourced and processed responsibly.

Conclusion: By-products Are a Smart Choice for Your Cat

By-products in cat food are not something to fear—they’re something to embrace. Far from being waste or fillers, they’re nutrient-rich, sustainable, and biologically appropriate ingredients that support your cat’s health in profound ways. From providing essential vitamins to reducing food waste, by-products play a vital role in modern pet nutrition.

In 2026, as pet parents become more informed and conscious consumers, the stigma around by-products is finally fading. With clear regulations, scientific backing, and growing transparency from top brands, there’s never been a better time to rethink what’s in your cat’s bowl.

So the next time you see “chicken liver” or “turkey heart” on an ingredient list, don’t panic—smile. You’re looking at some of the most nutritious, eco-friendly, and cat-approved ingredients available. Your feline friend will thank you with a shiny coat, bright eyes, and a purr that says it all.

Frequently Asked Questions

Are by-products in cat food safe?

Yes, by-products are safe when they meet AAFCO and FDA standards. They must come from inspected, human-grade animals and exclude inedible parts like hair or hooves.

Do by-products cause allergies in cats?

Not typically. By-products like liver or kidney are less common allergens than muscle meat. In fact, some hypoallergenic diets use novel by-products to reduce reactions.

Can kittens eat food with by-products?

Absolutely. Kittens benefit from the high nutrient density of by-products, especially vitamin A and taurine, which support growth and development.

Are by-products the same as by-product meal?

No. By-product meal is rendered (cooked down) to remove moisture, making it more concentrated. Both can be nutritious, but whole by-products retain more natural enzymes and moisture.

Why do some brands avoid by-products?

Some brands avoid by-products for marketing reasons, promoting “whole meats” as premium. However, this doesn’t mean by-products are inferior—just different.

How can I tell if by-products are high quality?

Look for named, species-specific by-products (e.g., “chicken liver”) listed early in the ingredients. Avoid vague terms like “meat by-products” and choose AAFCO-compliant foods.