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Tastes Like Chicken – The Science Dog

In recent times, dog house owners have began to demand more transparency from pet meals producers (a needed change, for my part). Many are focused on choosing new kinds of foods for their canine and like merchandise which are less extremely processed. In direct response to those developments, vitamin researchers have been learning the elements which might be used in pet foods, including the consequences of processing methods, corresponding to rendering,  cooking and feeding uncooked.

For instance, let’s take a look at hen.

Chicken Components: Chicken is one of the widespread animal-source proteins present in business canine meals and, like many animal-source proteins, is considered to be an entire protein for canine. Because of this it could possibly supply all the important amino acids in proportions that meet or exceed the canine’s every day necessities. The emphasis here is on the phrase can. As we’ll see, there’s evidence that not all hen elements present in pet foods are created equal.

Extruded (dry) pet meals embrace hen in the form of hen meal, which is produced from the by-products of the human food business utilizing a process referred to as rendering. (For an in depth rationalization of meals, see “What’s the Cope with Meals“). Chicken can also be found in pet meals within the form of retorted (canned), cooked or steamed, and raw.

Nevertheless, earlier than we take a look at these totally different types, we have to clear up a really primary supply of confusion in regards to the distinction between pet grade and human grade (aka “edible”) hen sources. That is necessary, so stick with me.

Framing the Difficulty: The overwhelming majority of animal protein sources which are included in commercially produced pet meals originate as slaughterhouse waste and from meals animals which might be deemed “not for human consumption” (officially categorized as inedible). In the case of hen, this comes within the form of  “chicken frames”, a term that refers to the portion of a hen’s body that is still after all the elements destined for human consumption have been eliminated and processed for the human food supply chain.


No, no, no. Not that.



Pet Food Grade Chicken: Chicken frames are composed of small bits of muscle meat plus a number of connective tissue and bone. It’s these hen frames, plus various quantities of inner organs, intestines, heads, and typically ft, which might be sent to rendering crops and processed into hen meal. They’re also the primary source of the “fresh” hen in dry dog foods which might be marketed as hen first. Although this labeling trick implies that this is identical hen as the food that buyers purchase in the supermarket, it isn’t. Somewhat, this hen can also be a by-product of the human food business – frames (and different stuff) – prior to being become a dry protein meal. The similar applies to commercially produced raw and recent cooked meals. Until the producer specifies “human grade” (technically referred to as “edible”), the hen components of their products are hen by-products – not grocery store hen breast and leg meat.

Human Grade Chicken: Some pet house owners are aware of this distinction and search meals that use human grade components. This matter is worthy of attention because it’s a tough difficulty. Present laws solely permit use of the phrase “human grade” on pet meals packaging if each ingredient and processing technique of the product meets FDA and USDA requirements for producing foods suitable for human consumption. Because solely a small number of pet meals corporations can meet these very stringent criteria, the inclusion of “human grade” on the meals’s label itself is comparatively rare. Nevertheless, corporations which might be buying solely human grade elements however that do not meet the standards of manufacturing their meals in a USDA-inspected human meals facility, can (and do) embrace this info on their web sites and by way of their advertising supplies.

High quality Differences? Though human grade components and finished pet meals that may be labeled as such are usually thought-about to be of higher quality, these foods are comparatively rare and are typically quite high in worth level. Additionally it is true that foods that use pet grade hen meals will not be essentially decrease in quality. Chicken meal high quality is influenced by cooking time, processing temperature and different circumstances. Quite a few studies have reported vast differences in quality in the hen meals and by-product meals which are used as components in pet foods (see “Dog Food Logic” for detailed info).

Nevertheless, till lately, nobody has in contrast the protein high quality of different forms of hen which are generally included in pet meals. This yr, a gaggle of nutritionists on the University of Illinois used multiple measures of protein high quality to match 4 varieties of pet grade hen (1). These have been:

  • Raw hen
  • Steamed hen (cooked to 200 degrees F for 10 minutes)
  • Retorted hen (processed as in canned meals; cooked at ~ 250 levels F for 30 minutes)
  • Chicken meal (rendered/dried)

The Research: The researchers used a rooster feeding assay that has been validated for determining protein and amino acid digestibilities. Prior research have proven that this assay’s outcomes correlate with outcomes from feeding trials with canine and it has been used to precisely calculate both protein digestibility and an estimate of essential amino acid availability (referred to as DIAA) in quite a lot of species.

Here is what they found once they compared raw, steamed, retorted and meal:


  • Digestibility: The general (dry matter) digestibility of hen meal was considerably decrease than the digestibility of the other three forms of hen. This distinction was pronounced. Only 60 % of the hen meal was digestible, in contrast with 73 to 76 % of the opposite varieties. Steamed hen had the very best digestibility worth (76.5 %); this was slightly larger than that of uncooked hen (75.9%), but the distinction between the two was not statistically vital.
  • Amino Acids: Apparently, digestibility values for all the essential and non-essential amino acids have been highest for steamed hen – higher than 90 % for all but two amino acids. These are rock star values, in the event you have been wondering. Raw hen did properly too – however not as well as the steamed ingredient. Across the board the amino acid digestibility values have been lowest in hen meal. Really low.
  • Chicken meal inadequacies: The researchers found multiple essential amino acid deficiencies in the hen meal ingredient. It was deficient in methionine, tryptophan and threonine compared with AAFCO recommendations for grownup canine. For progress, the hen meal met AAFCO recommendations for less than three of the 10 essential amino acids. (Wow.)
  • Raw vs. steamed hen: The knowledge in this research showed that average cooking offered profit over uncooked hen in the type of larger essential amino acid availability within the cooked hen. When values have been in contrast with AAFCO suggestions for adult canine, the steamed hen offered significantly larger amounts of all 10 important amino acids than uncooked hen. Nevertheless, both forms of hen met or exceeded the advisable ranges and have been thought-about to be top quality protein sources.

Take Away for Dog People: In this research, steamed hen was evaluated as the very best protein quality, adopted intently by raw hen. Retorted hen was of average high quality, whereas the hen meal, the type of hen that is included in virtually all dry, extruded dog meals, lagged dramatically behind and was found to be an incomplete protein supply for both grownup and rising canine.

Chicken meal performed poorly, really poorly, in this research. It had low digestibility and had quite a few amino acid deficiencies for each grownup and growing canine. Here is a direct quote from the paper:

“…. our knowledge indicate that if the hen meal has a low digestibility, it might not meet the minimal recommendations for indispensable [aka essential] AA with out supplementation, particularly if the food regimen is formulated to satisfy the minimal protein requirement of the canine…“

These outcomes are just like these reported in one other current research, carried out by a unique group of nutritionists (replication is necessary in science). I evaluation this research in “Thoughts your Peas and Potatoes“.

For my part, there are several essential factors to take away from this paper:

  • Raw claims: The belief of many who feed uncooked diets that raw meat (in this case hen) offers better vitamin to canine than cooked meat, is just not supported. The moderately cooked hen in this research was barely more digestible and offered larger ranges of obtainable essential amino acids than did the raw hen. Average cooking improved nutrient availability – it didn’t scale back it.
  • Chicken meal inadequacies: When included as the first protein supply in a food, hen meal might not provide enough levels of essential amino acids to growing or grownup canine,  Whereas this definitely is probably not true of all rendered hen meals, it was true of the supply that was examined in this research.
  • Meals selection? The drawback is that, (and I’ve crushed this specific drum before), pet house owners have absolutely no access to details about the ingredient high quality of economic pet meals. Because so few corporations use human grade elements and since those products that do are typically very excessive in worth point, this is not a helpful criterion for a lot of house owners. Although some pet meals corporations often measure the digestibility of their components and meals, this info isn’t usually out there to shoppers and corporations are beneath no regulatory strain to offer it. Consequently, in many instances, (based mostly upon private experience), queries to corporations for this info go unanswered. This can be a sad state of affairs indeed. Mockingly, the common directive from pet food manufacturers is that house owners should choose a pet food that is labeled as providing “complete and balanced” vitamin. Nevertheless, if a company isn’t testing or reporting high quality information about their meals, and we know that a minimum of some components are falling far in need of being sufficient sources of nutrients, how can we trust such recommendation or know that a declare of “complete and balanced” has been adequately substantiated? We can’t. And this can be a drawback.

Tastes like hen? In all probability.   Nutritious like hen? Perhaps not.

Cited Research: Oba PM, Utterback PL, Parsons CM, deGodoy MRC, Swanson KS. Chemical composition, true nutrient digestibility, and true metabilizable power of chicken-based components differing by processing technique utilizing the precision-fed cecectomized rooster assay. Journal of Animal Science 2019, in press.

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Thinking about learning more about the right way to critically evaluate and select the most effective meals on your canine? Learn Linda Case’s greatest selling guide, “Dog Meals Logic: Making Sensible Selections for Your Dog in an Age of Too Many Decisions“.