Organ meats: quality source of protein for pets

Opening our minds to using organ meats expands our base of raw ingredients and supports nutritional quality of a complete pet diet

By Greg Aldrich, PhD Release Date: Comments(0)

Organ meats have been called a multitude of names like viscera, entrails, tripe, paunch, offal and giblets. Despite the 18th-century monikers, they are the working internal organs, the guts, of the pig, chicken, cow, sheep or fish from which they derive. It might make you a bit queasy to consider them a food item, but rest assured dogs and cats consider them a delicacy...and with good reason.

These meats include such parts of the anatomy as the glandular stomach, small intestine, large intestine, heart, liver, lung, spleen, kidney, bladder, udder and others. They are fresh, chilled and frozen internal organs from animals and fish slaughtered under humane, sanitary and safe practices in our modern food processing facilities. Organ meats are sold as a combination described as “natural fall” or as individual parts.

The mass of raw ingredients may seem inconsequential when expressed as a proportion of the total animal live weight (approximately 3–5%). But realize that after specialty sausage products like headcheese and knackwurst take their cut, the remainder is almost the exclusive domain of petfood, so the volume is substantial.

By-product or delicacy—it’s in the eye of the beholder.

As a group, organ meats are wholesome, quality sources of protein and other nutrients. The folks feeding raw food, home-prepared diets and the out-on-the edge extreme performance diets have recognized the value of organ meats in their dog and cat diets for years. The value brands have quietly been customers, too. But in many petfood marketing campaigns, organ meats are being shunned because they are categorized derisively as by-products. By-product or delicacy—it’s in the eye of the beholder. Maybe the critics just don’t understand what dogs and cats really want.

Organ meats were part of canid and felid diets long before man came onto the scene. Following a successful hunt, our pets’ ancestors and their wild cousins of today rip into the soft underbelly of their prey as a first course. This is probably not only because it is an easier entry point to the body cavity, but also because these organs represent a rapid source of nourishment. For small wild felids that subsist primarily on a diet of rodents, they will eat their prey whole—organs included. So, in this day of “wild,” “primordial” and “ancestral” diets, it is all the more surprising that organ meats have the connotation of being an inferior product.

The data on the topic would suggest quite the contrary. As it turns out, organ meats have a high nutrient density, favorable nutrient profile and high digestibility. For example, Aldrich and Daristotle (1998) reported that chicken viscera and viscera plus heart and liver had a protein quality similar to chicken meat. Cramer et al. (2007) reported that pork, beef and sheep lung had a superior protein quality to that of chicken and fish.

Today, much of the organ meats wind up in the various rendered protein meals such as poultry by-product meal, meat and bone meal, pork meal, lamb meal or fish meal. Besides rendered protein meals, one can find viscera and other organ meats in a number of wet petfoods. The more value-based wet foods will also use a great deal of kidney, viscera, spleen, lung and udder.

The discrimination against their use is a Western bias, not a nutritional or safety matter.

For a few specific examples of organ meats’ application in petfood, let’s start with fresh chilled or frozen viscera. It contains a modest amount of protein and a relatively high amount of fat. In wet foods, viscera doesn’t bind terribly well, and at high levels, it can have a potent earthy aroma that pets seem to really like but pet owners may not find pleasing. So, viscera is often relegated to a supporting role.

As another example, pork kidney, due to its high protein content, is a popular ingredient in wet foods as a complement to liver. The limit to its use is typically 8–10% in this application. Lung and udder have a similar protein and fat composition to liver and kidney, but water content and handling must be factored into their use. Like other organ meats in a wet food, they are complementary to the primary protein; but due to high fat levels and limited binding, their inclusion is often best left as a supporting role.

Few products actually feature organ meats, but there are some exceptions. An example is wet foods that have “green tripe” in their name and as the primary meat. Also, organ meats feature prominently in the treat aisle as various products such as pizzles and bully sticks can be found. So, clearly we are selectively using these ingredients in both petfoods and treats today. To what degree becomes a matter of positioning and finding where organ meats serve the product design and appeal to the consumer making the purchase.

Organ meats are generally considered safe and wholesome. Remember, most of these meats are processed in US Department of Agriculture-inspected facilities and were intended for human consumption. The discrimination against their use is a Western bias, not a nutritional or safety matter. Of course, safe handling of any meat product is important; if the ingredient is mishandled, microbial spoilage and contamination with pathogens can occur.

As it relates to organ meats in petfood, the ski slope mantra says it best: “No guts, no glory.”

Research on the long-term use of organ meats in petfood is lacking, but no general issues are noted in the literature. There have been reports regarding environmental contaminants and heavy metals that can concentrate in organs such as the kidney and liver (Hankin et al., 1975); but again, the same concern is true for the human food chain. Process systems have been significantly improved since these reports were prepared nearly 40 years ago and should not be a factor today; however, diligence remains important.

Today, there are a few products extolling the virtue of organ meats in wet and dry extruded petfood applications. So perhaps the negative connotation of non-descript by-products has begun to wane. As Angele Thompson put it in a review article (Thompson, 2008), “There is a lot more to a cow than hamburger and to a chicken than chicken breast.”

The “more” she was referring to are organ meats. Opening our minds to their use in dog and cat diets clearly expands our base of quality raw ingredients, provides flavor our pets relish and supports nutritional quality of a complete pet diet. As it relates to organ meats in petfood, the ski slope mantra says it best: “No guts, no glory.”

Dr. Aldrich is president of Pet Food & Ingredient Technology Inc.