This article was published in the March 2022 issue of Pet Food Processing. Read it and other articles from this issue in our March digital edition.

There’s a popular descriptor on packaged pet food that is neither defined nor agreed upon by the pet food industry or pet nutritionists, according to Katy Nelson, senior veterinary relations manager, Chewy Inc., Dania Beach, Fla., and an associate veterinarian at the Belle Haven Animal Medical Centre, Alexandria, Va. It is “limited ingredient,” and pet parents have varied reasons for purchasing these products. The important consideration is what the ingredients are, not the actual number of ingredients.

“Generally, these foods have only one protein source,” Nelson said. “Or they feature a much smaller number of actual ingredients as compared to a company’s standard kibble product.”

Marge O’Brien, director, global market research and insights, Corbion, Lenexa, Kan., said, “Many trends that drive purchase decisions for human food often cross over into the pet aisle. When it comes to limited-ingredient pet food, there’s this realization that just as ‘pet parents’ have specific dietary needs, so do our furry friends.”

These needs may stem from real or perceived food allergies, usually to protein, as well as food sensitivities. By keeping the recipe simple, and limiting protein sources, these foods may be used to help diagnose and manage adverse food reactions in pets.

“Pet parents are concerned about possible food allergies,” said Carolyn Kennedy, director, CK Nutrition, Exeter, NH. “And while food allergies in pets are not common, many pet parents feel their pets do better avoiding certain foods.”

This is similar to how some humans claim to feel better when they avoid gluten, yet they have not been diagnosed with celiac disease. It’s that type of mindset that fuels pet parents’ efforts to find a food that helps their pet thrive.

“Skin issues are the No. 1 and No. 3 reasons dogs and cats, respectively, present to their veterinarian,” said Victoria Carmella, director, veterinary services, Blue Buffalo, a brand of General Mills Inc., Minneapolis. “Skin issues may be correlated to food sensitivities in both dogs and cats.

For pets with food sensitivities, formulations containing novel proteins such as alligator, lamb and venison can be a successful option, (Source: Blue Buffalo and Mars Petcare) “The use of non-traditional or novel proteins is very common in products intended to support animals with food sensitivities,” Carmella said. “The most commonly identified food allergens are typical protein sources, such as beef, dairy, chicken and wheat in dogs, and beef, fish, chicken and wheat in cats. Utilizing novel proteins in limited-ingredient products provides a nutritional solution to help manage animals with food sensitivities.”

Some dogs with chronic diarrhea may also have an underlying food allergy. It is estimated that 10% to 15% of dogs with a food allergy have gastrointestinal symptoms. Eliminating that food manages the problem.

“Limited-ingredient diets are based on the premise of what’s not in the food,” said Dana Paris, chief marketing officer, Canidae Pet Food, Stamford, Conn.

Canidae has grain-free and grain-inclusive limited-ingredient formulas. The grain-inclusive diets do not include peas or potatoes.

“It’s stressful for pet parents to handle dietary concerns, especially with so many products on the shelf to choose from,” Paris said. “We try to make the process as simple for them as possible. We list out all key ingredients right on the front of package for some products. Just like with people, the food our pets eat every day has a big impact on health and quality of life.”

How low can you go?

These things considered, limited ingredients come with formulation challenges. There are economic, nutrition, sensory and shelf-life targets to consider.  

Utilizing novel proteins in limited-ingredient products provides a nutritional solution to help manage animals with food sensitivities,” said Victoria Carmella, director of veterinary services at Blue Buffalo.

“Limited-ingredient pet foods can be difficult to formulate as it can be hard to reach the nutrient requirements with limited ingredients, and it can also be difficult to get the right flavor profile when you are limited in terms of animal origin ingredients,” Kennedy said. “Many functional marketing claims require the guarantees for certain nutrients or in some cases ingredients, so the marketing of a limited-ingredient pet food may be challenging, as fewer marketing call outs are possible.”

That is the “sell” of the limited-ingredient descriptive statement. Often those ingredients are flagged on front labels, sometimes even quantified. That’s what ACANA, a brand of Champion Petfoods, Edmonton, Alberta, Canada, does with its limited-ingredient pet foods. Front labels provide the percentage of single-sourced animal protein in the product. The duck and pear recipe, for example, flags that it contains 65% free-run duck ingredients.

Limited ingredient formulations will typically include just one or two ingredients each to meet the protein, fat and carbohydrate requirements. (Source: ©MONIKA WISNIEWSKA - STOCK.ADOBE.COM)

What formulators want to avoid is “multiple animal proteins, multiple carbohydrate-based ingredients and multiple fat sources,” according to Kennedy. “The key to a limited ingredient diet is to provide only one or maybe two sources of protein, fat and carbohydrates, and also to avoid all the ingredients that are unnecessary from a nutrient perspective, such as spices and herbs and other functional ingredients.

“Ensure you always are meeting the nutrient requirements for the pet’s life stage,” she added. “Also, try to avoid using ingredients that do not add anything but are only added for marketing claims.”

Paris suggested that when formulating a limited-ingredient food, start with the end product in mind. In other words, determine which ingredients to avoid from the start.

“Then fill in with premium sources of animal protein and wholesome, high-quality plant-based ingredients,” Paris said. “As with any formula, the nutrient profile is of critical importance, so formulation software and calculations should be used to create a diet on paper that meets nutritional needs, and then trials and lab testing should be done to validate those results.”

Carmella added, “Ensuring product integrity is essential when producing limited-ingredient pet foods. Robust quality control and assurance programs must be in place to reduce the risk of contamination from other ingredients utilized in the manufacturing facility.”

After all, if you are limiting the ingredients in the food, there’s no room for cross contamination or sloppy manufacturing. This would defeat the purpose of the product.

“We have very specific standard operating procedures regarding the manufacturing of these diets, which include precautions to ensure these diets are free of evidence of contaminating proteins,” Carmella said. “The limited-ingredient recipes offered by Blue Buffalo also feature high levels of antioxidants, such as vitamins E and C. Additionally, you’ll see that our formulas have added Omega fatty acids to support skin and coat health.”

“The key to a limited ingredient diet is to provide only one or maybe two sources of protein, fat and carbohydrates,” said Carolyn Kennedy, director of CK Nutrition.

Paris noted limited-ingredient diets often utilize non-traditional proteins. Canidae, for example, offers a wide variety of proteins to accommodate all diets. In its Pure Goodness line, there are formulas with salmon, duck, bison, lamb, goat and venison.

Such non-conventional proteins may come from other animal species, as long as they are approved for use. Examples include alligator, eggs, herring, kangaroo, rabbit, trout and whitefish. They may even be microbial proteins produced through fermentation.

Freely Pet LLC, Brentwood, Mo., focuses on flexitarian and vegetarian limited-ingredient options. The company uses varied proteins, including animal-derived, such as eggs, lamb, rabbit and turkey, as well as whole grains, namely quinoa. 

Avoiding cross contamination from other ingredients within a manufacturing facility is especially important for limited-ingredient diets. (Source: Blue Buffalo)

Duck has become quite popular in this space, as it is a nutritious and flavorful lean meat. It is comparable in fat and calories to a skinless chicken or turkey breast and an excellent source of selenium and zinc, nutrients critical for proper cellular metabolism. Duck is a red meat, which means it contains higher amounts of iron than other poultry.

Merrick Pet Care, Evanston, Ill., has de-boned duck as the first ingredient in its limited-ingredient pâté formulated to provide complete and balanced nutrition for cats with food sensitivities and sensitive stomachs. The product is grain and potato free, as well as void of artificial colors, flavors and preservatives.

Alligator meat is emerging as a sustainable ingredient for pet food. It is typically processed into a dry format, making it a concentrated source of protein that is well tolerated by cats and dogs.

Kemin Nutrisurance, Des Moines, Iowa, markets hydrolyzed, spray-dried whitefish that is about 90% protein and less than 0.5% fat. This composition makes it useful in low-density cat diets, as it allows formulators to hit nutritional requirements while maximizing topical fat application to drive palatability in these challenging formulations.  

Organ meats have room in limited-ingredient diets, too. Organs are a vital part of cats’ and dogs’ natural diets, as they provide essential nutrients not found in muscle meat. Organ meats have higher levels of B vitamins and are also rich in minerals, such as phosphorus, iron, copper, magnesium and iodine. They are also a good source of fat-soluble vitamins A, D, E and K.

Duck is popular in single-protein formulations for its nutritional profile, and offers a flavor pets favor. (Source: Canidae)

Ziwi USA, Overland Park, Kan., includes heart, liver, lung, tripe and kidney in all its cat and dog foods, as well as in its air-dried dog treats. Air drying is a natural way to preserve meat that eliminates the need for artificial preservatives, sugars or glycerins. The company’s slow, gentle, twin-stage air drying process crafts a food that is as nutrient-dense and digestible as a completely raw diet, but safe, clean to handle and can store for up to 21 months. In keeping with a true, limited-ingredient diet profile, Ziwi uses only organs from the same protein source as the muscle meat in each recipe.

“Limited-ingredient foods certainly have their place in the pet food space, as pet food is all about providing choices to pet parents,” Kennedy said. “The pet food industry’s job is simply to provide complete-and-balanced formulations, using Association of American Feed Control Officials’ approved ingredients, in many different formats to meet the industry demand for increased choices and a range of budgets.”

Read more about product development, ingredients and formulation.