Understanding Alternative Protein Sources for Companion Animal Food

Pet owners are more engaged than ever in managing their pet’s health. They want to decide what is best for their pet, including feeding what they determine to be the best nutrition. How do they make this determination? Through information obtained from their peers, pet store employees, marketing advertisements, search engine results, and their veterinary team. Pet owners’ values, ethics, and world views can also motivate their decision. This factor is leading many around the world to look for alternative protein sources, including ingredient sources for canine and feline diets.

While we know there is a global crisis for managing carbon, is there really a need to have alternative protein sources in companion animal food when we have well-established sources? Are there aspects of new protein sources that are more appealing? In preparing for nutrition conversations, veterinary teams need to know what they should expect to see in present and future pet diets.

Is It All a Marketing Hype?

Alternative and limited ingredient diets can fulfill dietary needs for pets with food intolerances or allergies. With the pet food industry projected to exceed $100 billion in 2023,¹ one may consider the alternative ingredient market to be nothing more than a marketing scheme. Some companies market pet diets to reflect human food trends despite a lack of evidence showing a health benefit for the pet. In this same sense, choosing products that are environmentally friendly does appeal to many consumers.

Environmental factors impact all ingredients in the food chain. Global warming, as a part of climate change, plays a role in drought conditions through altered water supply and extreme temperatures. These global warming environmental factors negatively influence crop production, contributing both directly and indirectly to the availability of plant and animal ingredients. These factors contribute directly by decreasing the production of grain crops, which are used as carbohydrate or fat (oil) sources, and indirectly by altering the number of available crops to be fed to production animals.

Crops also have to feed the human population. The world population is expected to increase from 7.8 billion in 2020 to 9.7 billion in 2050.² Our western diets are notoriously high in protein, and protein sources are generally the expensive component. As the population rises, the demand for meat protein is expected to rise by 75% by the year 2050.² This will lead to increased competition between humans and pets for premium ingredients. Traditionally, the pet food industry supports the human food industry by utilizing ingredients considered less desirable and ingredient coproducts to conserve waste. These ingredients, such as organs, bones, and other tissues, provide essential nutrients. While they are not generally part of everyday human nutrition in North America, they can provide natural sources of amino acids, minerals, vitamins, and other essential nutrients for a pet. According to the North American Renderers Association, 56 billion pounds of renderable raw material are diverted from landfills and recycled into usable fat, oil, and protein products in North America annually.³ So, what happens when we see pet diets matching the ingredients in human diets? Using the more desirable muscle portion of animal protein sources, for example, causes direct competition with human demands. If the pet food industry were to increase production of these more human-like diets, additional pressure would be placed on the food production and waste management chains.

Go Big or Go Home

The simple answer may be to focus on cultivating animals that provide more protein. This, of course, leads to increased land, water, and feed requirements. When comparing mammal and insect protein sources by size, land requirements, reproduction cycles, and food and water requirements, the bugs outcompete the larger, more common protein sources. There is also the environmental impact of larger ruminants to consider. Ruminants, particularly cattle, contribute to the carbon footprint through the release of methane gas. While many may think methane contribution is from manure, it is the eructation (belching) as part of normal ruminal microbial fermentation and digestive functions that releases the greatest amount of methane.⁴ Despite a great deal of effort to find nutritional ways to decrease ruminal methane production, increasing the production of ruminant protein sources is not a valid solution to meeting growing protein demands while considering the potential environmental impact.

Are All Proteins Created Equal?

Proteins are the foundation of many physiological functions. Proteins are the collection of larger, combined amino acids. To understand alternative proteins, we should first consider common protein sources. Beef, poultry (i.e., chicken, turkey, duck), pork, fish, lamb, goat, cereals, and milk proteins are commonly used in pet foods to meet the amino acid needs of dogs and cats. These products have been used in pet foods for decades and there is a generally good understanding of how to utilize them in this manner. Some alternative ingredients in the pet industry have been utilized as a nutritional source for other species, including humans. Legumes have been used for years and are gaining commonality in pet food, along with insect-based diets, which have long since been on the market as nutrition for birds, reptiles, and small mammals. An ideal new protein source would take less space for source rearing or growing, produce lower greenhouse gas emissions, use less water and feed to meet production demands, and decrease organic by-product waste.

What Are Ingredient Development Considerations?

As with most new things, there are various unknowns with new food ingredients: interactions, stability of availability, palatability, and, most importantly, health impact on animals. Nutritionally, the ingredient’s nutrient composition (i.e., what it provides) must be well understood. This information can then be compared to known ingredients identified as benchmark sources. For example, chicken has been a staple ingredient, and we understand what nutrients each component can contribute (e.g., white meat versus dark meat). Some alternative ingredients have developed these comparing assessments. Mealworms, for example, when used as a protein-rich food, can be compared to meat and milk. Houseflies and black soldier flies, as protein-rich feed ingredients, can be compared to fish meal and soybean meal. See FIGURE 1 and TABLE 1 for comparisons.

Figure 1. Comparing the land, feed, and water requirements of crickets to beef.⁵ Top (from left): vitals/shutterstock.com; Bigc Studios/shutterstock.com. Middle (from left): Parilov shutterstock.com; zefart/shutterstock.com (2); AMNAT DPP/shutterstock.com. Bottom (from left): symbiot/shutterstock.com; nhami8/shutterstock.com.

The Association of American Feed Control Officials (AAFCO) set out guidelines for the manufacturing of animal feeds by establishing definitions and protocols to assimilate feed production techniques. They also require that ingredients entering animal feed have completed a minimal level of research to ensure animal safety. For ingredient producers and manufacturers, it isn’t just about following the guidelines. The cost of developing alternative-ingredient pet foods will be higher due to the start-up costs of rearing or cultivating a new ingredient source; developing the product containing the ingredient; completing requirements for AAFCO, U.S. Department of Agriculture, and U.S. Food and Drug Administration guidelines; advertising and educating the public; and getting the product on shelves in front of consumers. Regardless of the consumer desire for an alternative protein diet, a higher price tag may cause hesitation in the initial purchase of these products.

What is Coming Down the Pet Food Pipeline?

Insects

As discussed, insects have been used as a food source for birds, reptiles, and humans in Eastern cultures. Many are high in digestible protein and have less environmental impact than commonly used sources (FIGURE 1). These sources may also supply polysaccharides that benefit microbial and host health through microbial fermentation and the production of short-chain fatty acids.⁷ Mealworms, crickets, and black soldier fly larvae (BSFL) can be found in pet diets and treats. According to a recently published paper in the Journal of Asia-Pacific Entomology, there are 43 brands active in the insect pet food world market, with the majority located in Europe.⁸

BSFL are an interesting protein source as the amino acid profiles can be manipulated depending on the substrate they are fed, the environment (i.e., temperature and humidity), larvae age when harvested, and the processing method used. While this might not mean much to the consumer, this becomes a formulation concern for pet food manufacturers. Ensuring that the ingredients provide the same nutrient level in each batch may mean additional testing and quality control measures are used. As a consumer, you must trust or do some due diligence to identify that a food company meets these quality control requirements. BSFL have a newly published AAFCO definition for canine adult maintenance, which allowed this ingredient to be among the first emerging alternative protein sources in 2023.⁹

Single-Cell Protein Sources (Yeast)

The coproducts from yeast, dried yeast, and yeast cultures are a viable ingredient source for animal feed. They are rich in proteins and are a palatable source for cats. A characteristic feature of yeast protein biomass is the high nucleic acid concentration when compared to traditional protein sources. The majority of cell nitrogen is derived from amino acids, while the remaining quantity of nitrogen comes from nucleic acids, especially RNA. Yeast protein biomass could be compared to meat meal, fishmeal, and soybean meal. Yeast coproducts (postbiotics) are microbial by-products and can be protein sources via peptides, enzymes, or nitrogen sources. Both yeast and yeast coproducts are viable environmentally friendly solutions to meeting pet protein needs. Diets are now showing up on the pet food market with yeast listed in the first 5 ingredients in the ingredient list.

Microalgae

High in polyunsaturated fatty acids, protein, and other valuable compounds, such as antioxidants and enzymes, microalgae grow in small amounts of water in large concentrations using few resources. Microalgae are more efficient than plants at carbon fixation, which is a part of photosynthesis. There are multiple types of microalgae and they each have varying levels of protein. When compared to the amino acid needs of dogs and cats, microalgae tend to be low in both methionine and cysteine. Some studies are now emerging in pets and microalgae diets, though none have focused on it as a major protein source. Due to the content of polysaccharides in the cell wall, the higher-level inclusion is correlated with decreased digestibility.¹⁰ See TABLE 2 for a full composition comparison.

In Vitro Meat Sources

The COVID-19 pandemic revealed crucial weaknesses in the global food supply chains. This led to researcher Laura Domigan winning a multimillion-dollar grant from the New Zealand and Singaporean governments in October 2020.¹¹ Her team was tasked to explore the ideal starting material for cultured meat and understand the nutritional profile of meat grown in a lab. In understanding the growth in this field, consulting firm Kearney estimates that 35% of all meat consumed globally by 2040 will be cultured.⁸ While this may seem very new, this type of science has been used since the early 2000s, when NASA (the National Aeronautics and Space Administration) briefly supported efforts to grow goldfish muscle in the lab as a potential source of protein for astronauts on long missions. Due to the current cost to develop cultured meat, it is more likely to be a delicatessen for the human food chain versus the pet industry.

Summary

Finding alternative proteins is more than a marketing scheme. Alternative proteins are a small part of the larger picture, serving as a component of food production, production animal feed, and feed for pets while minimizing waste and providing less environmental impact. Proteins are a necessary and expensive ingredient that provide the building blocks of many physiological processes, which makes research into their viability imperative. The race for providing the market with alternative protein sources includes high start-up expenses that will trickle down to the consumer. Monitoring AAFCO definitions for ingredients in animal feed is a way for veterinary professionals to monitor what alternative ingredients could be next in pet food for cats and dogs.