Pet Food Overview

Introduction

Definition

Pet food is animal feed that is usually intended for consumption by domestic pets. Categories of pet food are specific to the type of animal and include dog food, cat food, fish food, bird food, and small mammal food for species like rabbits, ferrets, hamsters, gerbils, and guinea pigs. Other segments of pet food include dry, wet, semi-moist, snacks/treats, and raw/frozen/refrigerated foods.

Dog and cat food make up the vast majority of pet food market size and products, with an estimated five billion pounds sold worldwide annually. Complete and balanced pet food is formulated to be the sole source of nutrition for most pets except in the case of treats and snacks, which are more specifically manufactured to create an enjoyable experience for both the animal and owner. In the case of small mammals, pellet food is best supplemented with fresh food like hay and vegetables to prevent excessive weight gain. Products generally consist of meat, poultry, and seafood and their byproducts, cereals, grains, soybean meal, vitamins, and minerals.

Most meat used in pet food is a byproduct of the human food industry and is not regarded as suitable for human consumption. Livestock, horses, and house pets that have been put to sleep are often used in pet food manufacturing. Animal parts that are used include damaged carcass parts, bones, cheek meat, intestines, kidneys, liver, lungs, udders, spleen, and stomach tissue.

Grains such as soybean meal, corn meal, cracked wheat, and barley are often used to improve product consistency and reduce the cost of raw materials. Water, meat broth, and blood can be added. Gelling agents help with homogeneity and moisture control. Palatability can be enhanced with yeast, protein, fat, fish solubles, sweeteners, or concentrated flavors. Vitamins and minerals are often added because some can be lost during the manufacturing process.

The key difference between dry and canned wet pet food is the moisture content and amount of fresh meat products. Dry pet food contains no more than 10% moisture and the predominant ingredients are corn gluten feed, meat and bone meal, animal fats, and oil. Amylaceous starch ingredients, proteinaceous adhesives like collagen and casein, and plasticizing agents are often added to give a texture like that of meat.

Canned wet food contains between 70% and 80% moisture and are mostly composed of fresh meat products, usually beef, pork, chicken, lamb, and their byproducts. Common fillers used in wet food include beet pulp, rice, corn, wheat, and soy. Semi-moist pet food contains 20% to 70% moisture and has a unique texture in that is it soft but not wet. It generally contains more sugar and salt from artificial color, chemical preservatives, and flavor enhancers than either dry or wet food. While appetizing to animals, semi-moist food is expensive and not suited to meet the nutritional needs of all animals.

There are distinct advantages and disadvantages to dry and wet food. Dry food is easier to store, has a longer shelf-life, and can be portioned into the desired ration more easily than wet food. Dry food also lends itself to better animal oral health. However, dry food is generally considered to have lower overall nutritional content than wet food.

Advantages of wet food include a larger portion of meal with equivalent energy calories as dry food due to higher water content and better palatability for most animals. As with animal feed manufacturing, pet food is specifically designed through feed formulation to meet the nutritional needs of the animals at different life stages. The primary difference between animal feed and pet food is that pet food is a retail product that must not only meet the nutritional needs of the animal, but must be made and marketed to be appealing to both the animal and owner. Thus, products are manufactured with specific flavors, textures, taste, and smells that are designed to make them stand out to animal owners and be enjoyed by the animal as well.

Advances continue in product design, feed formulation, manufacturing, analysis and marketing as the demand for pet food grows. New challenges will emerge and further research will be needed in all aspects of pet food development, especially for fast, innovative, and accurate testing methods.

History

Prior to the Industrial Revolution, dogs and cats primarily lived outside and ate raw meat or table scraps. The advent of a more affluent middle class led to dogs and cats becoming house pets.

The first commercial pet food was developed in 1860 in England by an electrician named James Spratt. He noticed dogs by the river in London eating leftover hardtack, the dry biscuits that sailors ate on trips at sea. The first manufactured pet food was Spratt’s Dog & Puppy Cakes, a mix of blended wheat, vegetables, beetroot, and “the dried unsalted gelatinous parts of Prairie Beef”. The product was expensive for the time and Spratt never revealed the source of meat during his lifetime. He showed considerable foresight by launching the product in America, strategic marketing by targeting health conscious pet owners and dog show participants, and pioneering the concept of manufacturing appropriate products for animals at different life stages.

By the early 1900s, new products were being developed as the market expanded and in 1922, the first canned dog food was developed in the United States. Ken-L-Ration was made of horse meat, stamped with a seal of government approval, and eventually held a 90% share in the dog food market. Interestingly, the meat used was horse meat but this was only disclosed in small letters at the bottom of the label while the product was marketed as “lean red meat”.

Before World War II, canned food was so successful that producers were slaughtering fifty thousand horses per year for its manufacture. During World War II, the combination of meat rations, pet food being labeled as a “non-essential” product, and outrage from animal lovers over the number of horses being slaughtered led to the creation of a new type of product. General Mills acquired James Spratt’s business in the 1950s and Ralston Purina began experimenting with the machines used for Chex breakfast cereal. There was a need to make pet food that could be stored for period of time and not use metal cans, as metal cans were rationed at the time.

In 1956, the first dry pet food known as kibble was produced using extrusion in a manner similar to the manufacture of shelf-stable human foods, such as breakfast cereals. Over the next two decades, using extrusion to produce dry pet food gained momentum with products with new flavors and varieties as well as marketing geared to convince consumers that commercially manufactured pet food was the best option for feeding pets.

The 1980s and 1990s brought on more niche based products marketed for the health of pets, such as prescription kibble for kidney and liver health and pet food based on individual activity level for weight management. Today, advances in feed formulation, manufacturing, and testing methods are facilitating the creation of new products, although extrusion is still the primary manufacturing process. Shelf-life and convenience remain the most important factors for pet food buyers. As demand for pet food continues to increase, there will be a need for new and innovative testing methods for proper product quality control.

Market Analysis

The global pet food market size was valued at $90.13 billion in 2019 and is projected to grow to $127.21 billion by 2027 at a CAGR of 4.6%. Dog food is the dominant segment in the pet food market at over 57% of market share. Cat food makes up approximately 35% while the remaining market share is comprised of bird, fish, and small mammal food.

A number of factors are expected to drive pet food market growth in coming years. There is an increasing rate of adoption and pet ownership worldwide. The percentage of pet owners who own more than one pet is also increasing, especially cat owners and cat ownership is expected to increase at a rapid pace in coming years as cats are both low-maintenance and human friendly. While the COVID-19 pandemic had a negative effect on many food markets as well as pet food due to supply chain disruption, it is also true that pet ownership increased during the pandemic and the market is expected to rebound from supply chain disruption over time.

As is the case with human food, there is increasing health awareness with consumption of pet food which is expected to drive higher demand for natural and organic products. Premium pet food using high quality, natural, and preservative-free ingredients is becoming increasingly popular. There is an easy availability of products with different price ranges, fueling the notion that customers with varying financial status can own a pet. Custom food products that are efficient in addressing particular pet health conditions are also increasing in demand, such as obesity and dry skin.

Dry food remains the preferred option for pets and pet owners and this is expected to continue in coming years. Dry food offers high convenience, easy portion division, good shelf-life, and strong contribution to oral health. Wet food is considered more palatable, easier to digest, and has better overall nutritional quality as well as the benefits of good hydration and better urinary tract health. However, it is more expensive and less convenient. Market competition is strong among major players, especially for high-quality food, snacks, and treats as these products are more distinctive in texture, color, and flavor. There are new products constantly being developed with powerful marketing campaigns to appeal to the desire of consumers and pets.

One factor that may hinder growth of the pet food market is increasing stringent regulations. In developed markets, pet food is strongly regulated at every stage of product development in a manner similar to human food, especially with marketing and product labeling. North America holds the majority share in the global pet food market. It is estimated that approximately two-thirds of the eighty-five million households in the United States own a pet and ownership is only expected to increase in coming years.

Over eighty million households in Europe own at least one pet and rate of cat ownership is high, making cat food the biggest segment in the European market. The Asia-Pacific region is expected to grow at the fastest rate during the forecast period, followed by South America. As market demand for pet food continues to grow, manufacturers will continue to create new and innovative products that necessitate the need for advanced testing methods.

Regulations and Labeling

Pet food is regulated in a manner similar to human food at both the federal and state levels. The FDA Food Safety Modernization Act (FSMA) was passed by Congress in 2011 to strengthen the food safety system and to shift the focus from responding to food supply contamination to prevention of it. All animal food facilities are required to create and implement a multi-part food safety plan.

In the first part of the plan, potential food safety hazards are assessed. In the second part of the plan, preventative controls are put in place for implementation when necessary to reduce or eliminate identified food safety hazards. Animal food facilities must also comply with current good manufacturing practices that provide baseline standards for manufacturing, processing, packing, and holding pet food to ensure that it is safe to eat. All FSMA requirements apply to companies required to register as an animal food facility because they manufacture, process, pack, or hold animal food for consumption in the United States.

Federal pet food regulations are enforced by the FDA and establish the following standards: proper identification of product, net quantity statement, manufacturer’s name and address, and proper listing of ingredients. State regulations vary but often follow the regulations established by the Association of American Feed Control Officials (AAFCO). These regulations are more specific than FDA regulations, covering things like product name, guaranteed analysis, nutritional adequacy statement, feeding directions, and calorie statements. Pet food manufacturers often use fanciful names for their products and these names often incorporate the name of an ingredient to highlight its inclusion in the product.

There are four AAFCO rules regarding the name of pet food products that are based on the percentage of named ingredients. The 95% rule applies to products that consist of very few ingredients. Names are usually simple, such as “Beef For Dogs” or “Tuna Cat Food”. The named ingredient must comprise at least 95% of the product on a dry matter basis or 70% of the product with added water. If the product consists of a combination of ingredients, the two ingredients together must make up 95% of the weight and the first named product must make up more of the composition than the second named product. For example, “Lobster and Salmon for Cats” must contain more lobster than salmon, with both ingredients making up 95% of the product.

The 25% or “dinner” rule applies to many canned and dry products. Ingredients that comprise less than 95% but at least 25% of the product (or a minimum of 10% with added water) must include some qualifying descriptive term, such as “Beef Dinner for Dogs”. Dinner is commonly used and other popular terms include Platter, Entrée, Nuggets, and Formula. However, the named product does not have to be the predominant ingredient and it is important for consumers to check the ingredient list in such products to ensure it does not contain an ingredient the pet is allergic to or that is unappealing to the animal. Like the 95% rule, if two ingredients are named the first ingredient must make up more of the product than the second ingredient.

The 3% or “with” rule allows manufacturers to highlight minor ingredients that are not added in sufficient quantity to meet the 25% rule. For example, “Beef Dinner for Dogs with Cheese” must contain at least 25% beef and 3% cheese. The regulation can be confusing as the difference between the tuna in “Tuna Cat Food” (meets 95% rule) and “Cat Food with Tuna” (meets 3% rule) is vast.

A specific percentage is not required under the “flavor” rule but the product must contain a sufficient amount to be detected. Testing using animals trained to detect specific flavors must be used to confirm the label claim. The substance creating the flavor does not have to be the actual ingredient, such as meal, by-products, or digests created to form concentrated natural flavors. As new pet food products continue to emerge, there will be increased demand for new and innovative testing methods to ensure proper label compliance.

Products and Composition

Dog Food

Dog food is food specifically formulated for consumption by dogs and related canines. They are considered to be omnivores with a carnivorous bias. Their digestive tracts are better suited for the consumption of meat than vegetables, but they are also capable of starch and glucose digestion as well as the ability to produce amylase, an enzyme that breaks down carbohydrates into simple sugars.

The most important ingredients in dog food come from meat, meat meal, and meat by-products which are the main sources of protein. Most commercial dog food brands use chicken, beef, or fish for protein. Meal has a high protein percentage and often is higher in protein and more nutritionally beneficial than whole meat. Grains make up the carbohydrates in dog food. Corn, soy, whole wheat, rice, oats, barley, and peas are common grains in dog food.

Fruits and vegetables are not essential for dog diets but they are beneficial and provide many vitamins and minerals. Sweet potatoes contain potassium, vitamin B, beta-carotene and antioxidants. Blueberries and apples are a good source of fiber, vitamin C, and antioxidants while cranberries assist with urinary tract infections and help dental hygiene by killing certain bacteria. Healthy fats provide energy, help absorb vitamins, and help keep coats and fur healthy and shiny. Good examples of healthy fats include Omega-3 and 6, fish oils, canola oil, chicken fat, and olive oil.

Vitamins and minerals are essential parts of any dog food. B vitamins help with metabolic, digestive, and immune system processes. Vitamin A is good for skin and coat health while Vitamin E also helps with the immune system. Important minerals include zinc, iron, potassium, calcium, and manganese. Natural preservatives help keep dog food fresh and proper water consumption, both from food and water itself, is essential for good health.

Dog food products can be dry, wet and canned, or semi-moist. All three types have distinct advantages and disadvantages and most products are specifically designed to be the primary source of nutrition for a dog. Snacks are designed for improving intake nutrition with enhanced quality products while treats are used as a key product to induce positive behavior in dogs. Dry food makes up the majority of dog food products and offers ease of storage and feeding as well as long-shelf life. It has a moisture content no higher than 10%. Energy composition has a higher density by weight than wet food and it is also cheaper than wet food. Dry dog food is good for oral health. However, the overall nutritional composition is usually lower than of wet and semi-moist food. Palatability is lower than that of wet food and grain composition is higher, which is undesirable for dogs with allergies. The extrusion manufacturing process also can denature the nutritional composition of the food.

Wet food has higher palatability and usually has a higher overall nutritional composition, especially in protein and healthy fats. Moisture content is between 70% and 80% and the higher moisture is good for hydration. However, the lower energy density can lend itself to weight gain, wet food can spoil easily, and it is more expensive than dry food. Semi-moist dog food contains between 20% and 70% moisture and is usually vacuum sealed. It has high palatability, has high energy content, and is convenient for dog owners. However, it contains artificial color, chemical preservatives, and chemical flavor enhancers as well as high levels of sodium and sugar, all of which can be detrimental to long-term health. It is also more expensive than both dry and wet food.

Advanced research in manufacturing and feed formulation has enabled the creation of specific products that help with dog health. Food exists for all life stages of different breeds of dogs as well as products that can assist with various ailments, such as obesity, poor liver and kidney health, and dry skin. As demand for dog food products continues to increase, there will be a need for new and more advanced testing methods to determine parameters of interest.

Cat Food

Nutrition required for cats is different from human or dog nutrition as cats are strict carnivores while humans and dogs are omnivores. Their diets need to consist primarily of meat and fish ingredients. Vegetables and grains should be limited.

The natural diet of cats comes from freshly killed meat from rodents, rabbits, amphibians, birds, reptiles, and fish and they will only consume certain plants and grasses to induce vomiting. As with dogs, protein is the most important part of a cat’s diet and should be the primary ingredient in any cat food. It is vital for growth, repair, maintenance, and immune system health at every life stage. High quality ingredients that are protein sources include chicken, beef, tuna, salmon, pork, turkey, and lamb. Organ meats like kidneys, heart, and liver contain many micronutrients that traditional meat does not have and they also enhance flavor and taste. Meat or fish meal like chicken, salmon, and lamb are high-quality and nutritious ingredients, although there is often a perception among consumers that they are lower quality than traditional meat. Most meats contain up to 80% moisture and in meals, the moisture is removed which makes for high nutrient density in protein, fat, and other nutrients.

Carbohydrates are not necessary in cat diets and can cause serious health problems in high quantities. In their natural environment, cats will consume less than 5% carbohydrates yet some cat foods contain up to 50% carbohydrates. The manufacture of such foods is entirely driven by cost as plant based ingredients are far cheaper than meat. High carbohydrate consumption can cause dehydration as well as liver and kidney problems. Fat is naturally present in meat and fish and provides a highly concentrated energy source. Healthy fats such as omega fatty acids are essential for maintenance and development of cells, muscles, and tissues. They can also improve fur and coat health, help with heart issues, and enhance cognitive function. There are a number of vitamins and minerals that are crucial to the health of a cat. Essential vitamins include Vitamin A, B vitamins B3 (Niacin) and B7 (Biotin), Vitamin C, Vitamin D, and Vitamin E. Calcium and phosphorus are important for strong bones and teeth. The amino acid arginine is crucial for the urea cycle and while fiber is not essential, it is good for gastrointestinal health.

As with dog food, both dry and wet canned food are made for cats and have advantages and disadvantages. While dry food is popular for its reduced price, ease of storage, and use in feeders as cats can be left alone for days with food and water feeders. However, dry food should not be the only type of food in a cat’s diet. Dry cat food can cause chronic dehydration and often has high quantities of unnecessary carbohydrates and fillers. Wet food is much higher in moisture and tends to have more balanced nutrition, fewer fillers, and less processed ingredients than dry food. However, it is more expensive and has a much shorter shelf-life than dry food.

Different cat foods are manufactured for different life stages. Kitten food has different ratios of nutrients and vitamins than adult cat food as well as a different consistency for easier digestion. Likewise, senior cat food contains different ratios of nutrients and vitamins and is often geared to help prevent health problems, such as joint and kidney issues. As advances continue in cat food feed formulation and manufacturing, new and innovative testing methods will be required to meet the increased demand for products.

Bird, Fish, and Small Mammal Food

Bird food is typically composed of seeds, nuts, or dried fruits and can be consumed by both wild and domestic pet birds. Pet birds can also be fed pellets which are specifically formulated and manufactured. Different types of bird food vary for different birds and their needs, such as whether they are carnivores or nectar eaters and how they use their beaks to crack the seed coat as hooked and straight beak birds are different in their seed cracking. Sunflower seeds attract the most types of birds and are the most common seeds used in wild bird feeders. Black oil sunflower seeds have a thin shell and are easy to crack open as well as having a high fat content, which is important for winter birds. Striped sunflower seeds are tougher for birds to crack. Other common seeds used for bird feed include safflower, sorghum, millet, rapeseed, and canary. While pellets are excellent for pet bird diets, they should be supplemented with a variety of fruits and vegetables for good health.

Fish food is manufactured in many different forms and like other types of pet food, it is specifically formulated to meet the nutritional needs for different species. Fish can be carnivorous, herbivorous, or omnivorous and need to be fed as such. Protein is the most important and expensive ingredient and is typically fishmeal or legumes like soybean. Fats comprise about 10% to 15% of feed for carnivores and 3% to 5% for herbivores. They are important for energy and provide about twice the amount of energy in fish diets than proteins and carbohydrates. The usual source is fish oil extracted from other fish, such as sardines. Vegetable oils extracted from canola and sunflower can also be used.

Carbohydrates are an economical source of energy and make up 20% to 30% in commercial feed. They are also useful as a binding agent, especially in feed that is designed to float. Some fish do not tolerate high amounts of carbohydrates and carnivores digest carbohydrates much worse than omnivores and herbivores. Various amounts of vitamins and minerals are needed although vitamins in processed food tend to degrade fairly quickly.

Other components of fish food include binding agents, preservatives, and attractants to improve palatability. The main types of processed fish food are pellets, flakes, and powders. Fish pellet food is manufactured in a similar fashion to traditional animal feed. It can be designed to float on water or sink. Advantages include slower decomposition in water which results in less water pollution and a long shelf life as smaller surface area reduces oxidation. It is usually fed to larger aquarium fish. Flakes will float for a period of time and then sink to the bottom of a tank. This gives fish at all levels of a tank a chance to feed and flakes are well suited for a tank containing multiple types of fish. Powdered food is also known as fry food and must be consumed quickly before the tank is polluted.

There are specialty fish foods designed for specific purposes. Color enhancing fish food contains carotenoids designed to make colors more vibrant and increase pigmentation. Medicated fish food is used to treat bacterial infections. Vacation fish food is designed to release food over one to two weeks if the owner is away from the tank for a period of time. Some fish are well-suited to eat live food as well.

Small mammals that are kept as pets include rabbits, guinea pigs, ferrets, rats, mice, hamsters, and gerbils. All have varying nutritional needs and like other domestic animals, there are commercially manufactured foods for them, usually in pellet form. However, many small mammals should be fed natural food as a supplement to pellets.

Rabbit food pellets are designed to promote rapid growth, weight gain, and ease of feeding. Once rabbits are full grown, pellet intake should be limited and supplemented with hay and certain fresh vegetables. A typical healthy pellet will have a fiber content of 18% or higher, a protein content around 12% to 14%, and a fat content no higher than 3%. The same holds true for guinea pigs, who require an outside source of Vitamin C for good health.

Guinea pig pellets should always have added Vitamin C and it is important to not let pellets sit too long as oxidation will degrade Vitamin C fairly quickly. Ferrets are similar to cats in that they are strict carnivores. While there are manufactured ferret feed products, they contain grains and carbohydrates that are not needed in their diet and can be harmful in excessive amounts. A tablespoon of high-quality cat food is a good supplement to commercial ferret food.

Rats, mice, hamsters, and gerbils all have similar dietary requirements. Their chow should have a minimum of 16% protein and 4% to 5% fat. Other foods can be fed with the commercial diet product but should not constitute more than 20% of the total diet. These include fruits, vegetables, grains, nuts, and seeds. Above all, a good feeding routine and balanced diet is essential for the good health of any type of pet.

Pet Food and NIR Spectroscopy

NIR spectroscopy has emerged as a fast, non-invasive testing method for parameters of interest in pet quality control. It offers the advantages of little to no sample preparation, the ability to be used for large-scale testing, and is able to determine multiple parameters with a single measurement.

The use of NIR spectroscopy has evolved from research and development studies in the pet food industry to being used extensively in practice by many large companies. Examples of macronutrients and energy components that can be determined using NIR spectroscopy include dry matter, crude protein, fiber, crude fat, carbohydrates, ash, metabolizable energy, and gross energy. As is the case with traditional animal feed, NIR spectroscopy can be used for analysis from the beginning to the end of the pet food manufacturing process.

The benefits of using NIR spectroscopy for pet food analysis are vast. It is used for raw material ID and component analysis as well as a tool for checking variation and shipment within batches. It is used as a real-time process control tool in the feed mill. NIR spectroscopy is also an aid for feed formulation by both determining variation in materials and giving manufacturers the ability to make mixing adjustments on the fly. When products are finished, NIR spectroscopy can be used for the final quality control check.

As a result, economic and return of investment (ROI) benefits, improved product quality, and maximization of resources are all proven benefits of using NIR spectroscopy. While the principles of NIR spectroscopy have been well-known for many years, recent technological advances have enabled its advancement as a practical tool in industry. Handheld and portable instruments have enabled analysis in the field. NIR spectroscopy requires the creation of calibration models to correlate NIR spectra to parameters of interest.

Companies have created pre-built calibration models for parameters of interest, reducing both the labor and costs required to implement NIR spectroscopy. This is important as many companies do not have the trained personnel for extensive scientific and calibration work and require the use of NIR spectrometers to be easy and simple. There are third-party programs that enable the use of web-based technology that support database management, quality control, and trend analysis to optimize processes and protocols for pet food analysis.

The largest pet food company in the United States has successfully adapted NIR spectroscopy for determining quality assurance. Material arriving on trucks is scanned and tested inside the original package before it even enters the facility and subsequent tests are performed throughout the manufacturing process. This company has had so much success with NIR spectroscopy that they even share the technology with competitors in the interest of creating safer pet food products for the entire industry, ultimately benefitting all manufacturers, customers, and pets themselves.

Advances will continue in using NIR spectroscopy as a pet food analytical tool and more trained and qualified personnel will be required for continued advancement.