A new protein source for pet food: cultivated meat

Supply issues

Pet food is a growing market that is responsible for around one-fifth of meat consumption worldwide (Knight, 2023). In the last two decades, demand for pet food-grade animal byproducts rose faster than the supply because of insufficient slaughter offal (Leenstra et al, 2018). The situation is further complicated by the premiumisation and humanisation of dog and cat food, with owners willing to spend more for higher-quality ingredients (Okin, 2017). As a result, around half of the animal ingredients currently used in pet food in the US are fit for human consumption (Knight, 2023). This trend exacerbates the substantial environmental, animal welfare and public health issues related to conventional meat production.

Sustainability

According to the numerous peer-reviewed life-cycle assessments published in the scientific literature, the environmental impact of pet food is non-negligible, as it accounts for 10–30% of the impact of animal-related food systems, depending on the country (Okin, 2017; Leenstra et al, 2018; Su and Martens, 2018; Su et al, 2018; Martens et al, 2019; Yavor et al, 2020; Pedrinelli et al, 2022). Cultivated meat could represent a solution to continue using animal ingredients in pet food at a significantly lower environmental cost. However, it is still too early to draw definitive conclusions regarding the sustainability of the cultivated meat industry, considering that it is still in its very early stages and has not reached an industrial scale. Nevertheless, peer-reviewed anticipatory life-cycle assessments show substantial environmental advantages when comparing cultivated meat with conventionally produced meat. Cultivated meat emissions are expected to be similar or slightly lower to poultry emissions, two times lower than pork and 11 times lower than beef, while land consumption is estimated to be 42–63% less than poultry, 65–67% less than pork and 90–94% less than beef (Mattick et al, 2015; Sinke et al, 2023). Additionally, cultivated meat manufacturing does not entail the production of animal waste, therefore guaranteeing substantial reduction of anthropogenic eutrophication (Mattick et al, 2015; Sinke et al, 2023). However, cultivated meat is expected to require more energy than beef, the most energy-consuming conventional meat – the respective ambitious benchmark for 2030 is 164 MJ per kg of cultivated meat compared to 104 MJ per kg of beef (Sinke et al, 2023). While it is expected that the energy needed to manufacture cultivated meat will decrease significantly as the process is scaled up and the cellular agriculture industry grows, relying on renewable energy will be essential to not invalidate the sustainability claims by using fossil fuels to produce cultivated meat (Sinke et al, 2023).

One Health

The conventional meat used for pet food is a significant contributor to three of the major issues of the One Health framework: food safety, zoonotic diseases and antimicrobial resistance. Commercial dry and wet pet food can harbour food safety pathogens such as Salmonella, which has been responsible for multiple outbreaks and large-scale product recalls (Lambertini et al, 2016). Raw meat-based diets represent an even higher risk (Morelli et al, 2020). In the UK, antimicrobial Escherichia coli was detected in the faecal samples of 54% of dogs fed raw meat and 17% of dogs fed pet food or cooked meat (Groat et al, 2016). By 2030, it is expected that the global consumption of antimicrobials in livestock is going to be equal to 108 million kg compared to the 48 million kg estimated for humans (Tiseo et al, 2020; Mulchandani et al, 2023).

Antimicrobial resistance also represents one of the biggest threats to the animal industry itself, because less effective antibiotics translate into slower growth and higher mortality rates. These, in turn, increase costs and decrease production. Using cultivated meat as a raw material instead of conventional meat would address these issues (World Health Organization, 2017). Antibiotics are not necessary to produce cultivated meat. The bioreactor environment must be sterile in order to allow the cells to grow – if microbial contamination were to occur, bacteria would out-com-pete mammal, avian and fish cells, leading to batch loss. Therefore, extremely high hygiene standards are mandatory to ensure harvesting, and the aseptic conditions required for the cells to grow make antibiotics unnecessary. However, this has yet to be achieved in large-scale bioreactors, where controlling the environment and contaminations could be more problematic than in small-scale ones. The only part of the cultivated meat production process where antibiotics are needed is to prevent contamination during pre-production cell isolation, but the amount of antibiotics used in this phase is in the order of milligrams.

Consumer demand

Pet owners are more likely to be vegetarian or vegan (Dodd et al, 2019). Therefore, many dog and cat owners face the so-called ‘vegetarian dilemma’: they are not consuming meat themselves for ethical and/or environmental reasons, but they are feeding it to their pets (Rothgerber, 2013). The only currently available peer-reviewed consumer acceptance study on cultivated meat-based pet food showed that among consumers who are unwilling to eat cultivated meat, the majority of vegans and vegetarians (55.9%) would still feed it to their pets, while only a few meat eaters would (9.6%) (Oven et al, 2022). Among respondents willing to eat cultivated meat themselves, more than 80% would feed it to their pets. The demand for alternative protein-based pet food is rising, as demonstrated by the growth in plant-based and insect-based pet food. Therefore, consumer adoption of cultivated meat-based pet food will be driven mostly by cost, palatability, nutritional value and health effects of the diet.

Information presented to the consumers and the way it is presented will also play a significant role. The impact of framing on acceptance of cultivated meat has been investigated in the human food market. When cultivated meat is framed as a technological innovation, it is significantly less appealing than when the focus is on its societal benefits or its similarity to conventional meat. Similarly, names such as ‘lab-grown’ meat are less appealing than names such as ‘cultivated’ or ‘cultured’ meat (Post et al, 2020).

Manufacturing

The production of cultivated meat for pet food applications can be summarised into three phases (Figure 1). First, a cell bank is created using cells isolated with a biopsy from a living animal or a fertilised egg. The cell bank is preserved frozen. Second, cells are thawed in small flasks and moved to bioreactors, which are sterile containers where cells are fed a nutrient-rich medium to allow them to grow under controlled conditions. Once the cells have grown sufficiently and reached the desired density, the medium is filtered out or bioreactors are drained into centrifuges for harvesting. During the harvest, the medium is separated from the cells. The resulting cell biomass has a consistency similar to meat slurry. The third step is the inclusion of the harvested unstructured biomass in the final pet food formulation. This food processing stage will vary based on the end product (dry pet food, wet pet food or fresh food). Compared to the production of cultivated meat for human consumption, some of the technical challenges are avoided: there is no need to develop scaffolds to recreate the complex three-dimensional structure of meat, which, besides muscle cells, also includes fat, blood vessels, nerves and connective tissue (Post et al, 2020). Nevertheless, three major scale-up challenges need to be overcome to reach industrial manufacturing at a scale sufficient to satisfy commercial demand and make the process profitable:

Safety

Cultivated meat is a new ingredient produced with an innovative method, which requires a demonstration of safety for pet food use. Adverse reactions to food can be classified as chemical/pharmacological and microbiological (European Pet Food Industry, 2021). The latter is caused by the presence of a pathogen (food infections) or toxin (food intoxications). The sterile environment required for cultivated meat production minimises the risk of microbiological contamination of the final product. However, contamination could still happen during the post-harvesting food processing phase, so the final pet food should still be monitored closely. For cultivated meat as a raw ingredient, chemical/pharmacological toxic reaction represents the main hazard that requires a risk assessment. The chemical hazards can be divided into specific and non-specific cultivated meat hazards. The management of specific cultivated meat hazards is based on five main strategies:

Non-specific cultivated meat hazards (eg bioaccumulation of antibiotics, heavy metals and other contaminants, as well as undeclared ingredients and cross contaminations with other protein sources), are common among conventional animal products and cultivated meat allows instead for a significant risk reduction.

Nutrition

Comprehensive nutrition data for cultivated meat-based pet food are not yet publicly available. It can be expected that the nutritional profile of the products will vary significantly based on the type of cells used, because different cell types contribute different sets of nutrients; for example, myocytes and fibroblasts are the primary sources of protein, while adipocytes are the main contributors to the fatty acid profile for flavour and taste (Rubio et al, 2020). Considering the current limits in the scale-up capabilities for low-cost cultivated meat, it is likely that the first few cultivated meat-based pet foods will be hybrid products that contain traditional sources of protein and fat together with cultivated meat derived from a singular type of cell line, eg plant-based pet food with a partial inclusion of cultivated meat. This would be similar to what has been done for human products, eg plant-based nuggets with a partial inclusion of cultivated chicken cells (Pasitka et al, 2023). During these early stages of the industry, it will be useful to determine where cultivated meat can add the most value at the lowest inclusion rate. For pet food applications, cultivated meat should be considered as a category of raw ingredients, just as traditional meat and fish. When discussing the nutritional profile, one must refer to the specific cell line and product at hand. The medium formulation will also significantly impact the nutritional profile – in the same way, conventional meat nutritional profiles can vary based on what the animals are fed (Rubio et al, 2020).

The composition of macronutrients in most meat products typically ranges from 70–75% water, 20–25% protein and 1–10% fat (Wood, 2017). Based on available public data on two cultivated chicken meat products for human consumption currently approved in the US, cultivated meat is expected to have a similar composition: 75–90% water, 5–20% protein and 1–5% fat (Food and Drug Administration, 2023). Based on this initial evidence, both amino acid and fatty acid profiles are expected to be similar to the corresponding conventional meat profiles (Food and Drug Administration, 2023). However, no data on taurine or arachidonic acid (essential nutrients for cats that are typically animal-derived) are publicly available yet. Interestingly, there is strong potential for nutritional optimisation by feeding the cells different amino acids and fatty acids and modulating the other medium components during the growth phase; for example, this could allow for control of the lipid profile to modify the omega-6:omega-3 ratio (Fish et al, 2020).

Cultivated meat can also contribute to the micronutrient profile if vitamins and minerals are taken up by cells from the medium and accumulated in the biomass. In general, many compounds that accumulate in the muscle and that are found in conventional meat are not produced directly in it, but derive from animal feed components metabolised by other organs. These compounds would be absent in cultivated meat unless they were to be added to the culture medium and taken up by the cells. Supplementing the medium with vitamins, such as B12, and minerals, such as iron, zinc and selenium could allow the harvested biomass to contain these nutrients in significant amounts (Broucke et al, 2023). Aside from assessing the nutrient profile, it will also be important to investigate the palatability, digestibility and bioavailability of cultivated meat-based pet food. Finally, understanding the effect of cultivated meat on pet health will be essential. While humans will eat cultivated meat as one of the many ingredients in their diet, pets are likely to be fed the same diet every day. Therefore, cultivated meat-based pet food must be proven to be a safe and healthy diet for repetitive long-term consumption. For this reason, after short-term palatability and digestibility trials, longer studies should be conducted to monitor the effect of cultivated meat-based pet food on general health parameters, haematology, serum biochemistry, serum nutrient concentrations, microbiota and other health outcomes.