This article was published in the January/February 2025 issue of Pet Food Processing.
Feeding trials play a critical role in ensuring pet food meets the highest standards of safety and nutrition. By evaluating how well dogs and cats thrive on specific diets, these trials provide essential real-world insights into digestibility, bioavailability and overall health outcomes.
From carefully designed protocols to detailed measurements of vitality, feeding trials reveal what laboratory tests alone cannot. They help pet food manufacturers refine their formulations, address common challenges, and adapt to emerging innovations in nutrition science — all with the goal of improving the lives of pets.
Ensuring safety and nutrition
“Feeding trials provide pet food manufacturers an opportunity to demonstrate that dogs or cats are able to effectively metabolize a new pet food,” explained Austin Therrell, executive director of the Association of American Feed Control Officials (AAFCO), Champaign, Ill. “Chemical analyses can often estimate this but cannot replace understanding how successfully an animal will digest and metabolize a particular formulation.”
“Feeding trials provide pet food manufacturers an opportunity to demonstrate that dogs or cats are able to effectively metabolize a new pet food,” said Austin Therrell of Association of American Feed Control Officials.
While lab analyses provide important baseline data, feeding trials offer a deeper understanding of how pets respond to specific formulations in the real world. These trials are especially valuable when evaluating novel ingredients or innovative diets, ensuring they meet nutritional standards without compromising long-term health.
“The main goal of the feeding trials is to ensure that the food properly sustains the pet over the long-term without adverse outcomes,” said Claire Timlin, Ph.D., director of research and development, Four Rivers Canine Research, Walker, Mo. “They’re especially important for diets that may be using novel ingredients that have not been as prevalent in the pet food industry historically or are gaining interest after use in human and livestock diets, since every species is different.”
For even more comprehensive results, feeding trials can include additional health assessments beyond the basic requirements. These evaluations provide a fuller picture of a pet’s overall wellbeing, highlighting potential issues that may not be immediately visible.
“For a more robust feeding study, additional health parameters should be measured, including comprehensive bloodwork, body condition scoring, as well as specific measures such as cardiac health in some cases,” said Bradley Quest, DVM, principal of veterinary services, BSM Partners, Bentonville, Ark. “This may help detect any adverse effects or signs of toxicity in pets consuming the food and includes observing and measuring physical and other clinical markers such as weight, stool quality and overall health.”
Design and protocols
Conducting feeding trials involves following established protocols to ensure consistent results while maintaining a strong focus on animal welfare. These protocols are carefully designed to meet industry standards and regulatory guidelines, providing consistency across trials.
“A typical AAFCO maintenance feeding trial will last six months, and during this time we measure daily food consumption, weekly body weights, and general blood work (complete blood counts and chemistries). Dogs are also examined by a vet at the beginning and end of the trials,” Timlin said. “A diet is considered to pass the trial if dogs do not show any clinical or pathological signs of deficiency or excess, individuals do not lose more than 15% body weight and the average group does not lose more than 10%, and blood analyses stay within healthy reference ranges.”
Strict adherence to these protocols ensures both scientific rigor and ethical standards. Oversight by organizations like the Institutional Animal Care and Use Committee (IACUC) reinforces the commitment to animal welfare, which is central to every feeding trial.
“Feeding trials are designed following the protocol outlined in the AAFCO Official Publication (OP),” said Katy Miller, DVM, director of veterinary services, BSM Partners. “Most take place at Clinical Research Organizations (CROs) that, in the United States, require oversight by committees like the IACUC to ensure the ethical treatment of animals in research. This requirement is mandated under the Animal Welfare Act (AWA) and further reinforced by the Public Health Service Policy on Humane Care and Use of Laboratory Animals (PHS Policy).
“Some feeding trials and even AAFCO feeding trials can also be conducted as in-home studies if done in a controlled manner to ensure compliance. Some pet food companies prefer this model when conducted by veterinary professionals,” she added.
Key measurements
Feeding trials track behavioral observations in addition to physiological measurements that can provide an in-depth understanding of the diet’s impact on the pet.
| Source: AFB InternationalA variety of essential data is collected during trials to evaluate the safety and effectiveness of pet food. These measurements go beyond basic observations, offering deeper insights into a pet’s health and wellbeing over the course of the trial.
“The animals’ choices, the consistency they eat, the food chosen and total consumption are essential measurements,” said Becca Hampton, animal care technician and palatability coordinator, AFB International, St Charles, Mo. “During, before and after testing, the behaviors are also monitored, as well as stools, to ensure health and safety.”
Behavioral observations are complemented by physiological measurements that provide a deeper understanding of a diet’s impact. This data offers a comprehensive view of how a diet supports a pet’s health and identifies any potential risks.
“During AAFCO feeding trials, several specific factors and outcomes are measured to evaluate the safety and nutritional adequacy of pet food over a period of 26 weeks (six months). Initial, weekly and final body weights are recorded to monitor growth (for puppies and kittens) or weight maintenance (for adults). Signs of adverse reactions such as vomiting, lethargy or poor appetite are monitored daily. Fecal quality (consistency, color, frequency) is evaluated and recorded. Blood parameters (total protein, albumin, alkaline phosphate, hemoglobin and packed cell volume) are taken and measured at the start and end of the study,” Quest explained.
In addition to these measurements, daily or weekly food consumption is tracked to assess the pets’ energy intake. Tracking weight changes provides a snapshot of the diet’s impact on overall energy balance. These observations collectively confirm whether the pet food meets nutritional requirements and avoids harmful side effects.
Insights beyond the lab
Real-world insights into palatability, bioavailability and long-term impacts emerge through trials that go beyond the scope of lab-based nutritional analyses. These trials observe how pets interact with food in natural settings.
“The best way to see how an animal responds to a food, is to feed it,” Timlin said. “The basic proximate analyses that are run for the label can tell us about the macro- and micronutrients in the food, but they don’t take into account the bioavailability of the nutrients (how well the animal can absorb and use the nutrients). A food source might say it meets the animal’s requirements for a certain nutrient, but if the animal is not able to absorb and use the nutrient properly, they may be missing out on necessary nutrition. We are starting to see that different food sources offer variable bioavailabilities of nutrients.”
Observing pets over time reveals long-term dietary effects, from changes in feeding habits to sustained acceptance of formulations. These real-world insights help manufacturers refine recipes.
“Feeding trials show real-world results that cannot be seen otherwise,” Hampton said. “In a lab, you cannot confidently say that a cat or dog prefers a particular food. We can show that animals can detect small or large flavor changes and how they change preference and consumption. The after-effects are also able to be monitored to give information otherwise not known.”
Challenges and innovations
Despite their importance, trials come with challenges such as high costs, logistical complexities and ethical considerations, pushing manufacturers to innovate.
Initial, weekly and final body weights are recorded in feeding trials for puppy and kitten food.
| Source: ©NYNKE - STOCK.ADOBE.COM“AAFCO feeding trials, while essential for demonstrating the nutritional adequacy of pet food, present several common challenges for manufacturers,” Miller said. “Identifying healthy, representative animals for the trial can be difficult, especially when the gestation/lactation and growth stage is evaluated. AAFCO feeding trials are resource-intensive, requiring significant time, financial investment, and logistical planning. This makes it important to employ experts familiar with AAFCO guidelines to oversee trial design and execution. Other limitations include the small sample sizes and limited duration, which may not fully capture long-term effects or the variability in individual pet responses, as well as some pet food companies having objections to using research facilities.”
Feeding trials often focus on baseline metrics, such as maintaining weight and meeting minimum nutritional requirements. However, this narrow scope can overlook other vital aspects of pet health. Broadening the evaluations can ensure well-rounded health outcomes and improve the overall reliability of trial results.
“One issue I think is that the guidelines laid out in the AAFCO publication for feeding trials cover the bare minimum: does the dog maintain weight and do their blood chemistries remain within normal ranges. However, there are many other areas that pet owners would consider when assessing the health of their pets, like stool quality, skin and coat condition, and general activity levels,” Timlin explained.
These gaps in evaluation highlight the need for more practical approaches during feeding trials. Addressing real-world variables, such as how animals interact with feeding setups or how their unique behaviors influence data reliability, adds depth to these studies.
“Side bias on bowls, fast-eating animals, overeating animals and older animals present challenges,” Hampton said. “Retraining is done periodically, and validating the cats and dogs is necessary to check testing levels and ensure we provide the best quality data.”
To address challenges such as high costs, logistical complexities and ethical concerns, the industry is turning to innovations like biomarker analysis, microbiome research and wearable technology. These solutions aim to tackle issues such as refining study methodologies, better capturing variability in responses, and reducing reliance on traditional research facilities. This not only enhances data quality but also helps overcome logistical challenges.
“I think as pet owners become more in tune with their pet’s health, we’ll see even more demand from pet food companies for feeding trials that go beyond the AAFCO protocol to measure the dog’s health,” Timlin said. “Companies are also wanting more scientific data to support their diets, especially when it comes to the microbiome, inflammation and age-specific formulas. Our understanding of companion animal nutrition is always improving, and as technology progresses, more advanced analytical methods become more affordable and easier to incorporate into these types of studies.”
By leveraging advanced tools like biomarkers and microbiome analysis, manufacturers are enhancing the precision and reliability of feeding trials. Innovations like artificial intelligence-powered image analysis, long-term trials focused on chronic diseases, and in-home testing environments are also reshaping the landscape. These developments streamline processes, address ethical concerns and provide actionable insights, paving the way for a future where feeding trials not only improve nutrition but adapt to evolving industry standards and consumer expectations.
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