Evaluation of the "meal" and animal by-products in pet meals

Beyond the Marketing Hype – What We Need to Know and Need to Know About Protein Ingredients in Commercial Dog Food. A deeper look at the types of food so many of us give our dogs.

In May 2014, Nestlé-Purina, the largest producer of pet food sold in the United States, filed a lawsuit against competitor Blue Buffalo Dog Food. The lawsuit alleged, among other things, that Blue Buffalo's marketing claims – that their food contained no by-products – were false and derogatory for the products of other companies.

According to a report from a test lab hired by Nestlé-Purina, at least some varieties of dry extruded Blue Buffalo foods (snacks) actually contained poultry by-product flour, which in some cases made up as much as 25 percent of the flour products. As is customary in the modern pet food industry, Blue Buffalo responded within a few days with its own counterclaim, accusing Nestlé-Purina of defamation, unfair competition and false advertising.

At the center of this public (dog) food fight was the belief, strongly advocated by Blue Buffalo, that chicken or poultry meal is superior in nutritional value to by-product meals and that high-quality dog ​​food contains the former and rejects the latter. (It is of interest to note that Nestlé-Purina circumvented the nutrient quality issue in their lawsuit. Rather, they alleged that Blue Buffalo falsely advertised itself as completely transparent to its customers.)

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Initially, Blue Buffalo responded to the allegations with rejection. Both companies launched public relations campaigns that included highly worded letters to "pet parents" (i.e., consumers). However, in October Blue Buffalo had to eat crow (meal?) When they announced that one of their suppliers, Wilbur-Ellis of Texas, mislabelled an ingredient, resulting in poultry by-product meal in some of their foods.

In the words of Blue Buffalo Founder, Bill Bishop, “While your customers were ordering and paying for 100 percent chicken meal, they were receiving intermittent shipments that contained poultry by-product meal. As a result, we have discontinued business with this system. "

What is the truth? Are by-product meals of inferior quality compared to meals? Should discerning dog owners avoid chicken or poultry by-product meal and only choose foods that contain chicken or poultry meal? And is this a reliable way of distinguishing between high quality dog ​​food and lower quality food?

Perhaps the best place to start is to understand what a "meal" is.

Meals, the protein ingredient

Each ingredient that goes into a dog food contains a unique set of essential nutrients that contribute to the finished food. Various types of meals are used in commercially produced dry (extruded) dog foods to provide protein. These meals can be classified in different ways.

First, a meal can be plant-based or animal-based. Examples of commonly used plant-based protein meals are corn gluten flour, soybean meal, and pea protein (or flour). In general, vegetable sources of protein are an inexpensive source of protein and can be found in foods marketed to pet owners who are thrifty. The quality of these meals is moderate to low in terms of amino acid balance and digestibility, although various sources of protein are used to ensure that all essential amino acid needs are met.

On the other hand, protein meals from animal sources vary considerably both in terms of the source – animal species – and in terms of quality measures such as digestibility, amino acid content and availability of amino acids. Examples of species-specific meals commonly used in pet food are chicken, bison, beef, salmon, lamb, game and turkey meals. These meals can also be classified more heavily as poultry (contains different amounts of chicken, turkey, or duck), fish (contains more than one species of fish), or meat (contains different amounts of pork, beef, or sheep).

Animal meals are made commercially by rendering, a cooking process that converts slaughterhouse products that have been classified as unfit for human consumption into a form that is classified as acceptable for use in pet food. In general, animal parts that are used for rendering are those that are not normally consumed in our western diet: organ meats such as spleen, kidneys, liver; Stomach and intestines; different amounts of bone; and in the case of poultry, necks, feet and heads.

In addition to slaughterhouse waste, “used” laying hens from the egg industry and feed animals that have been classified as too sick or injured to pass the inspection for use as human food can end up in the processing facility. Classified as “inedible” during the slaughter process, these parts are diverted to an alternative supply stream and handled, transported and processed differently than those intended for human consumption.

During the rendering process, the combined components are ground, mixed, and heated to a high temperature (220-270 ° F) which cooks the product, kills microbes, and sterilizes the mixture. Sterilization is necessary because no refrigeration is required to handle or transport inedible food.

The resulting slurry is then centrifuged at high speed to remove lipids (fat). The removed fat is further processed and finally sold separately as chicken, poultry or animal fat. The remaining mixture is dried and ground to a uniform particle size that ultimately has the appearance and texture of dry cornmeal. Animal protein meals are very low in moisture and contain between 55 and 65 percent protein, which makes them a rich source of protein when included in an animal feed.

From a commercial point of view, meals are well suited for use in dry foods because of their ease of storage and transport and the low moisture content required for extrusion processing. In comparison, moisture-rich protein components such as “fresh” chicken (or other meat) only add small amounts of protein to the end product, as the water is boiled off during the extrusion process.

These ingredients can be listed first on a food's ingredient list simply because they contain more than 60 percent water. At the time of processing, the ingredients must be listed mainly by weight. In reality, it is the dry meals, usually found in the first three to five ingredients of the list, that make up most of the dietary protein in dry dog ​​food.

Meals and by-product meals defined

The term "by-product" is the identifier that receives the most attention.

It is important to note that this term on pet food labels only applies to chicken and poultry meal. This distinction is largely bureaucratic; The Association of American Feed Control Officials (AAFCO) sets the definitions for ingredient terms and they have not established a by-product meal term for any other animal protein ingredient. The closest they come to "meat" meals compared to "meat and bone" meals. The latter contains bone, which can affect its quality as a protein source.

What exactly is the difference between chicken (poultry) flour and chicken (poultry) by-product meal?

According to AAFCO, the term “meal” refers to the “dry, rendered product of a combination of clean meat and skin, with or without accompanying bones, obtained from parts of whole carcasses of (chicken / poultry) without feathers and heads, feet and viscera . "(AAFCO 2010)

While this definition suggests that meals are made from the same parts of the chicken that go to the supermarket for human consumption, it is not. As previously mentioned, animal protein meals are made from slaughterhouse waste and other feed animals that are considered "not for human consumption" (i.e., inedible).

In the case of chickens, this is the "chicken frame" or what is left of a chicken's body after the parts intended for human consumption have been removed. More than 70 percent of a broiler chicken ends up in the supermarket, and around 30 percent remains in the frame, which is made up of some lean muscle and lots of connective tissue and bones. In fact, no meals are made from edible meat (for humans) as rendering plants take in inedible animal components and convert them into a form that can be fed to non-human animals.

Chicken (or poultry) by-product meal, on the other hand, consists of the same chicken components that are included in meals, with the difference that by-product meals can also contain different amounts of head, feet and intestines. . Hence, the difference between a chicken (or poultry) meal and its respective by-product meal is the inclusion of the head and neck, feet and viscera (intestines) in the latter and the exclusion of those body parts from the former.

At first glance, this seems like an obvious difference in quality. After all, any product that contains the head, feet, and viscera not only sounds happy, but surely has to be of poor quality too, right? It depends on.

Is one better than the other?

Given this definition, the common (and understandable) perception is that meals are of higher quality than meals with by-products. This is clearly the conclusion that Blue Buffalo and other pet food companies make "No By-Products!" Claims are made on their labels.

However, consistent and significant quality differences between the two types of ingredients are not reported. The fact is that including extra body parts (heads, feet, and viscera) in by-product meals can decrease, maintain, or improve the quality of a meal. (Aldrich, Daristotle 1998)

While these three extra pieces may not be very appetizing for most people, they have different nutritional values ​​than food ingredients.

First, the protein quality of the intestines (internal organs and intestinal contents) is similar to that of chicken meat ingredients found in very high quality chicken meals (and what people consume in a chicken dinner). In other words, including organ meat and intestinal contents in a by-product meal does not negatively affect the protein quality of the meal and may even improve it in a meal of poor or average quality.

Second, the inclusion of chicken heads in the mixture leads to a slight decrease in nutritional quality. This is because chicken brains are very digestible while chicken skulls are less digestible as bones. So it seems like a zero sum game when it comes to the added chicken heads.

Finally, chicken feet. As a food ingredient, feet are simply bad and have measured quality values ​​that are similar to the feeding of connective tissue or bone debris. (However, this does not prevent them from being enjoyed extensively in some cultures.)

Taken together, the inclusion of additional body parts in a by-product meal can either positively or negatively affect the protein quality of the resulting product compared to the corresponding meal. How and how much they affect it depends largely on the actual proportion of the three different body parts that are included in the final product. When there are many viscera, the quality improves. Heads: could go either way. Feet: bad news. Incidentally, details of the type and amount of these supplements are information that a consumer is never familiar with.

Why all the hype?

Studies of the digestibility and protein quality of meals and by-product meals have found that meals as a group are slightly more digestible and contain slightly more available essential amino acids than the associated by-product meals. (Locatelli, Howhler 2003; Cramer et al. 2007)

However, there is also a lot of overlap between the two groups of ingredients, meaning that a particular meal may be better, the same, or even of lesser quality than a particular by-product meal. Overall, the observed differences are neither dramatic nor worthy of the hysteria that the word “by-product” seems to accompany with dog owners and some pet food companies.

Therefore, the marketing hyperbole and excessive "pat on the back" of companies that contain meals but no by-products should be viewed with a hefty dose of skepticism by all dog owners. True, there are some differences, but probably not enough quality differences to warrant the inflammatory language and excessive claims made by companies jumping on the by-product-free bandwagon.

Ironically, consumers have no direct way of knowing whether the meal used in the food they choose is low, medium, or high quality, let alone the extent of the difference between a particular meal and a by-product meal. In addition, there is no evidence to suggest whether the measured and reported differences between chicken meal and chicken by-product meal have an impact on the overall nutritional health of dogs.

I would suggest that this exaggeration of the difference occurred (and was actively promoted) because there are so few ways for dog owners to accurately assess the quality of the ingredients in commercial pet foods. As a result, that single AAFCO-defined difference (meals versus by-product meals) has caught on like a house on fire. Marketing campaigns hurl extra gasoline to fuel the flames, causing that distinction to be made indiscriminately more important than it warrants.


If you're interested in doing your own detective work, get in touch with the company that makes your dog's food and ask them the following questions. You can find the company's customer service number on the bag. Alternatively, most companies offer a "Contact Us" email or chat service on their website. If you get answers, you are on your way to being an informed consumer.

> Which supplier supplies the protein meal (s) in your food? Ask about both the company's location and the source of the rendered products.

> Does the company require its ingredient suppliers to meet certain nutritional and safety standards for protein meals? If so, what are these standards?

> How does the company measure the quality of the protein meals contained in the food?

> Does the company measure the digestibility of its food based on feeding tests? If so, what is the digestibility of this product?

What we know – and don't know

It is an unfortunate paradox that one of the most important nutrients for dogs (protein) is provided by some type of ingredient (protein meals) that consumers can barely judge. This is particularly worrying as meals from animal sources can vary widely in the ingredients they are made of and, ultimately, their quality (i.e., nutritional content and digestibility). What information is available to consumers and what is hidden from us? Unfortunately there is much more of the latter than the former.

Animal source proteins are generally more balanced in terms of amino acid content compared to plant based proteins and should be the preferred sources of protein in a quality diet. When evaluating protein meals from animal sources, choosing a meal from a specific type is helpful. In general, if you see a named species – chicken, beef, salmon, duck, or bison – as the main ingredient of protein flour, it means the food is of higher quality (or at least a more regulated product).

Ingredient supply companies must keep those ingredient streams separate and labeled, which means the sources are not mixed and translate into a more consistent product and regulatory control.

Conversely, the generic term that is used to describe a group of feed animals (poultry, meat or fish meal) means that the flour can contain a mixture of species without a specific animal species or certain animal proportions being guaranteed in a specific meal. At the production level, this also means that several ingredient streams with different sources of origin, official supervision and quality characteristics are combined.

In addition, the species source that is cheapest in the market at any given time may increase in proportion to their respective meal. Because of these differences, generic (combined) meals are cheaper for pet food manufacturers than species-specific meals.

The fact that these three identifiers – plant / animal sources, species vs. Generics and flour vs. By-product meal (for chicken / poultry) – being the only quality designator for protein components available to consumers, may not be a problem if they are in fact the main quality differences between animal protein meals. However, this is not the case. Animal protein meals differ in ways that are invisible to consumers and can significantly affect the quality of the foods in which they are used.

Protein meals from animal sources contain varying amounts of bone and connective tissue (this applies to both meals and by-product meals), which have an impact on the protein quality and mineral balance of the product. The bone matrix and connective tissue contain the protein collagen, which is poorly digested and used as a nutritional source of protein, and bone contributes to excess amounts of calcium and several other minerals. Meals that are high in collagen and minerals from bones and connective tissue are of lower quality than those that are higher in muscle meat.

Since inedible food is not refrigerated or is subject to the same handling regulations as food intended for human consumption, both the handling and the transport of raw materials can affect the quality of the end product. When rendering is done at the origin slaughterhouse, the flour is usually made within a day or two of slaughter.

However, when raw materials are transported to a rendering facility at a different location, the time spent under uncooled conditions during transport can lead to increased microbial contamination and oxidative damage.

Differences between rendering systems also exist and are important for the end product. High temperatures or cooking too long can damage the protein in a meal and make certain essential amino acids less digestible and less available.

As seen in the Blue Buffalo case, pet food companies are at least somewhat dependent on the integrity and honesty of their ingredient suppliers. A division within the animal feed industry describes some meals as animal feed grade and others as feed grade, with the former containing a lower percentage of ash (minerals). (Dozier et al. 2003)

Additionally, some pet food companies only select meals that meet a certain standard, while others impose additional refining methods on their protein meals to improve digestibility and improve protein quality.

Various analytical tests are used to measure the digestibility and availability of amino acids in a meal, and many pet food companies also routinely measure the digestibility of their food through feeding trials. However, this information is not readily available to consumers, and pet food companies are not required to accept or refuse meals of varying quality or to provide this information to consumers.

To date, there has been no way for pet owners to distinguish between dry dog ​​foods that use high quality animal protein meals and those that use low quality meals other than the cost of the food and the three identifiers discussed above. You can of course contact the company and specifically ask for information about the protein digestibility and quality of the food.

However, you may be disappointed. While researching my book Dog Food Logic (2014), I contacted the manufacturers of more than 30 different pet food brands and asked for information on protein and diet digestibility for each of the products. I received no response at all from the majority of the companies and useful information for only two of the brands.

Are there any other options? There are actually quite a few in today's innovative marketplace. Two other animal protein ingredients (in addition to home-cooked fresh meat) are those that are either freeze-dried or dehydrated.

Freeze-dried ingredients are typically used in raw food diets, but can also be cooked before packing. Dehydration usually uses heat treatment to kill microbial growth and so the meat is cooked moderately. These sources are likely to be of higher quality and more digestible because they have not undergone the high heat processing that meals are exposed to.

If it is human quality meat, all the better as it means that the ingredients and finished products have been handled and manufactured using the same regulatory oversight as for human food. However, with a few exceptions, neither freeze-dried nor dehydrated meat sources are routinely used as the primary protein source in dry, extruded foods.

Also, I have not found a source of dried protein meals made using human grade meat sources (i.e. edible) and human food processing methods. Doing so (and promoting them as such) would add a dimension of choice and differentiation to dry dog ​​food quality that is no longer available today.

Dry extruded dog food is still the most popular type of dog food sold in the U.S. and I believe such products are welcomed by owners willing to pay a little more for a more regulated, higher quality food.

While rendered animal meals can be high quality and can be an excellent source of protein in dry dog ​​food, protein from animal sources that has been poorly sourced, handled, processed, or regulated can be damaged, making it a poor source of essential amino acids for dogs and reducing the digestibility and quality of the overall diet.

Unfortunately, consumers cannot tell from the label of a food whether the meal they are eating is of high, moderate or poor quality. Since meals make up the majority of the protein in dry dog ​​food, information about their quality and also how nutritious they are is the most important consideration to consider when looking at an ingredient list.

The problem is that, despite the fact that companies that hit the drumstick "No By-Products" want to believe, we still have no way of knowing which animal protein meals are better than others.

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