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Methodology for evaluation of pet food

Throughout history, humans have been associated with dogs and cats in various ways, for protection, rodent control, hunting, and society. As a result of their domestication, the nutrition of dogs and cats has changed from hunting and eating the remains to their current form. Changes in the human diet through the development of agricultural practices have supported this shift. In the United States, 63% of pet owners consider their pets to be family members (AVMA, 2012b). The anthropomorphism of dogs and cats has led pet owners to prefer pet foods that contain ingredients they find in their own diet and are processed to maintain the nutritional integrity of the ingredients and ensure feed safety. Current trends in the human diet in developed regions of the world include more fresh fruits and vegetables (Barnard, 2010) and whole grains (Griffiths, 2010). This paradigm has resulted in the emergence of the pet food segment.

Dog food is a diet specially prepared and intended for consumption for dogs and other related beasts. Dogs are considered omnivores with carnivorous preferences. They have sharp pointed teeth and a shorter gastrointestinal tract of carnivores, are better suited to eating meat than plant substances, but they also have 10 genes that are responsible for digesting starch and glucose, as well as the ability to produce amylase - an enzyme that works by breaking down carbohydrates. for simple sugars - something that typical carnivores lack. Dogs developed the ability to live alongside humans in agricultural societies because they were able to eat leftover food from humans. For thousands of years, dogs have been able to adapt to survive on bits of meat and non-meat remnants of human existence and thrive on a variety of foods. Studies suggesting that dogs' ability to easily digest carbohydrates may be a key difference between dogs and wolves.


Cat food is a diet specially prepared and intended for consumption for cats. Cats have specific nutritional requirements. Some nutrients, including many vitamins and amino acids, are degraded by the temperatures, pressures and chemical treatments used in production, so they need to be added after production to prevent nutritional deficiencies. Cats are exclusive carnivores - meaning that they are dependent on the nutrients present in the animal's body to cover their dietary needs. Even domesticated cats prefer freshly killed meat from rodents, rabbits, amphibians, birds, reptiles and fish. However, cats also accept cooked food and dried cat food. Cats' natural diet does not include any vegetables, although cats occasionally eat certain plants and grasses, usually due to their emetic effects.


Petgroot is an aggregate personalized platform operating in the pet segment, which includes a rating of pet food. Petgroot focuses on parameterizing large amounts of data on feed origin, processing, composition, quality, health impact, transparency of production and environmental sustainability. The feed score index is based on a constantly evolving collaborative dynamic algorithm that takes into account the latest scientific and technological knowledge concerning the production and distribution of pet food.



Natural diet

The natural diet, including instinctive or ancestral diets, is based on feeding domestic animals according to their physiological abilities or preferences, and not only leading to meeting the regulatory definition of a natural pet product. Instinctive nutrition is based on the philosophy of feeding domestic animals according to their natural preferences, and it is assumed that the animals will choose their own diet to suit their nutritional needs. The ancestral diet is based on the philosophy of feeding domestic animals a diet similar to their evolutionary ancestors, and it is assumed that such a diet is in accordance with the physiological needs and metabolic abilities of companion animals. Regardless of the philosophical basis, both instinctive and ancestral diets usually contain higher protein concentrations and lower carbohydrate concentrations than most dry pet foods on the market. There are no regulatory definitions of instinctive or gender diet; therefore, the nutritional composition of commercial animal foods may not be exactly related to instinctive or generic nutritional philosophies.


Instinctive diet

Recent research using nutritional geometry in a controlled environment has shown that dogs of different breeds choose a macronutrient profile in which 30% of their ME comes from proteins, 63% from fats and 7% from carbohydrates (Hewson-Hughes et al., 2013). Similar research in cats suggests that they select 52% of their ME, 36% of fat, and 12% of carbohydrates from protein (Hewson-Hughes et al., 2011). Given their strict carnivorous nature, it is not surprising that cats show a preference for eating higher protein content compared to dogs. In contrast, dogs appear to consider dietary fat to be particularly tasty, which corresponds to the minimal adverse effects of a high-fat diet on healthy dog ​​populations (Bauer, 2006). However, it is not known whether the above distributions of macronutrients provided optimal nutrition, given that the preferred levels of macronutrients are significantly different from the minimum requirements or recommended allowances given in the NRC (NRC, 2006).


Ancestral diet

It is known that domesticated dogs evolved from wolves (Canis lupus lupus; Serpell, 1995). Archaeological evidence suggests that dogs were the first animal domesticated by humans about 14,000 years ago (Clutton-Brock, 1995). Domestication of cats is newer than in dogs, because the remains of cats from 6,000 years ago were found in Cyprus (Serpell, 2000). As a result, some dog foods are marketed with a high protein content of meat that is suitable for wolves and their presumed evolutionary association and genetic resemblance to dogs. However, domesticated dogs are no longer wolves, because domestication such as Canis lupus familiaris has changed not only their social and cognitive attributes, but also the types of food that are suitable for them (Hemmer, 1990). Recently, evidence has been published in which certain specific mutations in key canine genes compared to wolves provide functional support for increased starch digestion (Axelsson et al., 2013) compared to the carnivorous wolf diet (Stahler et al., 2006). This supports Serpella's previous report (1995) that dogs came from a subset of wolves that were more socially adapted to human contact. These data help explain the omnivorous nature of domestic dogs versus carnivorous wolves.


In nature, it seems that the primary component of a dog's diet is animal protein, but as mentioned above, domestic dogs can also get nutritional benefits from plant sources. Wild dogs are known to hunt in packs and eat a wide variety of foods. The diet of wolves consists mainly of animal proteins and usually hunts larger prey, such as moose, eats organs with a high density of nutrients, followed by muscle tissue (Stahler et al., 2006). Analysis of 50 diets consumed by wolves showed an average nutrient intake of 35.5 g of protein, 13.2 g of fat and 0.8 g of carbohydrates per MJ ME, reflecting the macronutrient profile of 52% ME from protein, 47% ME from fat and 1 % ME from carbohydrates (Hendriks, 2013). Wild dogs usually hunt small prey and look for fodder and berries of some plants (Boitani and Ciucci, 1995). Jackals (Canis aureus) often look for cultivated fruit and consume large amounts of grass (Ewer, 1973). Wild dogs need to develop a considerable amount of energy in order to obtain food, and therefore consume foods that are more readily available in the environment in which they live. This evidence supports the hypothesis that dog species are highly adaptable to different diets, and the diet they choose is determined by the environment in which they live.


Mitochondrial DNA analysis has shown that the domestic cat (Felis catus) is the closest relationship to the European wild cat (Felis silvestris), the African wild cat (Felis libyca) and the sand cat (Felis nigripes; Johnson and O'Brien, 1997). These species of feral cats resemble a domestic cat and an African feral cat that has been bred as a pet (Smithers, 1968). In most wild species (Serpell, 2000), many of the behavioral symptoms observed in domestic cats, such as shaking, meowing, hissing, and squeaking, have been observed.


Most cat owners feed their cats industrially produced conventional pet food because it is convenient and economical. Compared to dogs, however, cats need a higher concentration of moisture in the diet. Conventional cat foods can contain up to 55% ME in the form of carbohydrates, which allows a minimum content of protein (25% ME) and fat (20% ME) set by the American Association of Feed Control and The European Pet Food Industry Federation. However, the most common cat foods contain only between 20% to 40% ME in the form of carbohydrates. Carbohydrate components, such as grains, potatoes, legumes, etc., composed mainly of starches, are important for the processing of pet food. A certain level of starch must be included for the proper processing of dry fodder. The main function of carbohydrates in the processing of extruded dry food is to ensure the structural integrity of the granule. Dry food cannot maintain its form or structure without the carbohydrate binding capacity. It is boiled gelatinized starch that binds the granules together and prevents crushing. The interactions of the carbohydrates and proteins present also contribute to the texture and taste. Most wet feeds contain gelling agents, which are usually carbohydrates that form a gel after processing. The starches gelatinize with the denaturing protein to obtain the desired structure while maintaining an even distribution of the composition. Texture characteristics also vary greatly between carbohydrate sources, as each source responds uniquely to temperature and time.


In recent decades, so-called alternative approaches to eating have become popular, such as feeding bone, raw foods, raw meat-based diets, home-made or commercially produced fresh meat diets, and vegetarian and vegan diets. The survey showed that 9.6% of cats receive bones and raw foods as part of their main meal. These raw diets are often used by owners who want to provide their cats with a more natural diet (ie minimal processing and less grain content). These types of alternative diets usually contain lower amounts of carbohydrates compared to traditional commercial diets. Proponents believe that this alternative diet brings benefits to the health of cats, while opponents of this approach mention the risks and possible complications. There are no cohort studies evaluating these putative benefits and risks. One recent study showed better apparent digestibility of dry matter, organic matter, crude protein and crude energy in kittens fed a raw diet compared to heat-treated diets. On the other hand, there is evidence that raw meat diets can be contaminated with pathogens (eg Salmonella, E. coli, Campylobacter). Animals exposed to these pathogens may show clinical signs or may be clinically normal and excrete bacteria in the faeces.


The natural diet of feral cats consists mainly of small mammals, birds, fish, invertebrate reptiles, with a macronutrient profile of 52% ME from proteins, 46% ME from fat and 2% ME from carbohydrates (Plantinga et al., 2011). Studies of the preferred macronutrient profile of domestic cats suggest instinctive dietary preferences of domestic cats that are very reminiscent of the nutritional composition of the wild feline diet (Hewson-Hughes et al., 2011). Studies comparing the digestibility of different eating habits of exotic captive cats and domestic cats were performed. These studies did not find any major differences in digestibility. Differences between domestic cats and jaguary were observed for digestibility of DM, CP, fat and GE (P <0.05). Differences were also observed between domestic cats and Amur tigers in terms of digestibility of DM, OM, CP, fat and GE (P <0.05). In addition, differences were observed between domestic cats and Malaysian tigers in terms of digestibility of CP, fat and GE (P <0.05). No differences were observed between domestic cats and cheetahs. A later report from the same laboratory (Kerr et al., 2013) compared the total tracts of domestic cats, African wild cats (Felis silvestris tritrami), jaguars and Malaysian tigers fed a raw meat-based diet. In this study, no differences were observed between species in terms of digestibility of DM, OM and GE. However, they found differences in the apparent overall digestibility of CP between domestic cats and Malaysian tigers, but no differences were observed in the digestibility of CP between domestic cats and other species. In contrast to the evolution of dogs, cats appear to have retained much of their dietary preferences, behavioral attributes, and physiological digestive functions as a wild species.

Physiology and metabolism

The basis of a natural diet, including instinctive and ancestral diets, is the satisfaction of nutritional needs and the alignment with physiological and metabolic abilities to support the health of domestic animals. Therefore, for a better evaluation of the extent to which such diets are suitable for companion animals, a certain evaluation of the digestive physiology of both the dog and the cat is important.


Both dogs and cats have the ability to digest carbohydrates enzymatically (maltase, sucrose and lactase) (Hore and Messer, 1968). Morris et al. (1977) showed that cats are able to efficiently digest glucose, sucrose, lactose, dextrin and starch (apparent digestibility 94-100%). In addition, cats are reported to have lower enzymatic activities for carbohydrate digestion compared to other species (Kienzle, 1993a, b, c, d) and physiological responses vary according to carbohydrate type and heat treatment (Kienzle, 1994). These results indicate that although cats have the ability to digest carbohydrates efficiently, their carbohydrate digestion capacity may be limited, as evidenced by digestive disorders such as diarrhea, flatulence and bloating when there are high carbohydrate concentrations (> 5 g / kg BW)). are fed (Kienzle, 1993b).


Compared to humans, dogs have an increased fat oxidation capacity and generate twice the amount of energy from fat oxidation at rest and during exercise (McClelland et al., 1994). However, dogs have similar postprandial responses to humans in carbohydrate metabolism, with carbohydrate levels and type dictating a glycemic response (Nguyen et al., 1998; Carciofi et al., 2008; Elliott et al., 2012). For example, when 12 working dogs were fed a high-protein (49%) diet with a low carbohydrate content (13%), they had a delayed maximum glucose concentration on glucose responses compared to when they were fed a low-protein (22%) diet with a higher carbohydrate content (13%). 45%) (Hill et al., 2009).


Feline metabolism is adapted for gluconeogenesis rather than glucose clearance, including no detectable hepatic glucokinase activity and higher pyruvate carboxylase, fructose-1,6-bisphosphatase, and glucose-6-phosphatase activities in cats compared to psymphs (Washizu et al., 1999 Tanaka et al., 2005). However, there is currently limited evidence to suggest that moderate dietary carbohydrate concentrations impair the metabolism or health of cats (Verbrugghe et al., 2012). For example, both high (47% energy from carbohydrates compared to 26-27%) and low (7% energy from carbohydrates compared to 25-29%) dietary carbohydrate levels reduce insulin sensitivity in cats (Farrow et al., 2002 Verbrugghe et al., 2010). In addition, while protein intake of 48% versus 28% energy from protein does not affect insulin sensitivity (Leray et al., 2006), high dietary fat concentrations (51% energy from fat compared to 33%) reduce glucose tolerance in cats (Thiess et al., 2004).


Although protein or essential AA intake above the recommended limit has not been found to provide an additional benefit to pets, there is evidence to suggest that it is beneficial during physiological conditions such as obesity and strenuous exercise training. High protein diets (> 100 g crude protein / 1,000 kcal ME) have been shown to effectively facilitate weight loss in obese dogs while maintaining a lower body weight (Diez et al., 2002; Blanchard et al., 2004; German et al. , 2010). Hoenig et al. (2007) examined the effects of weight loss on a high-carbohydrate / low-protein diet (28% protein / 38% carbohydrate) and a high-protein / low-carbohydrate diet (45% protein / 25% carbohydrate) on weight loss. Weight loss modified selected hormones and other metabolites independently of diet. These researchers also found that a high-protein diet was beneficial in cats to maintain normal sensitivity to insulin fat metabolism during caloric restriction. It should be noted that studies demonstrating the beneficial effects of higher protein levels in obese or obese companion animals have also used caloric restriction and often lower fat concentrations than the natural diet to achieve these benefits.


A diet high in protein (> 30% ME from protein) or fat (> 50% ME from fat) has been shown to have a beneficial effect on performance in dogs. Adaptation of fat to more than 50% ME from fat has been found to improve aerobic performance (Downey et al., 1980) and save glycogen utilization in dogs (Reynolds et al., 1995). The Beagle, which was fed a high-fat diet (53-67% energy), ran 20 miles (140 minutes) without problems, while the Beagle, which was fed a low-fat diet (29% energy), ran out after only 15 miles ( 100 minutes) (Downey et al., 1980). High levels of carbohydrates (60% ME from carbohydrates), a low-fat diet (15% ME from fat) given to draft dogs led to higher (P <0.05) resting glycogen concentrations in muscle compared to high fat (60% % ME from fat) and low carbohydrate content (15% ME from carbohydrates). Glycogen utilization rates were higher during anaerobic exercise; therefore, the final muscle glycogen concentration did not change (Reynolds et al., 1995). In racing dog sleds, protein concentration is also important, due to the progressive development of stress anemia below 32% of the ME protein (Kronfeld et al., 1994). In contrast, moderate protein and fat levels (24% ME from protein, 33% ME from fat and 43% ME from carbohydrates) proved to be more advantageous for sprint dogs, as shown by race times (32.43 ± 0.48 vs 32.61 ± 0 , 50 s; P <0.05) at a distance of 500 m (Hill et al., 2001).


The studies described above support the hypothesis that the physiological and metabolic abilities of dogs and cats are consistent with the preferred levels of instinctive nutrition of macronutrients, which is especially evident under physiological conditions of stress, such as aerobic exercise.


Adjusting macronutrient levels to ensure optimal nutrition is particularly important with regard to the modern lifestyle of domestic animals, in which companion animals live predominantly indoors and are less active than their wild predecessors. Feeding is becoming a critical issue in maintaining higher protein and fat levels for inactive pets, especially due to evidence of negative health effects of weight gain (Lund et al., 2005, 2006). In addition, feedings high in animal protein adversely affects the environmental sustainability of the diet (Reijnders and Soret, 2003). The inclusion of carbohydrates in pet food is in line with the concept of environmental nutritional sustainability while promoting the health and nutritional needs of pets (for a full review, see Swanson et al., 2013). Partially meeting the energy needs of carbohydrates while meeting AA and fatty acid requirements allows for the modest inclusion of greener and more economical sources of protein and / or fat in pet food, especially where there is competition from certain sources for human food ingredients.

Whole ingredients

Pet foods have historically been formulated on the basis of nutrient content, given that animals have specific requirements for nutrients and not for ingredients. In the pet food segment, consumers and producers are increasingly focusing on so-called “whole” ingredients, with the term “whole” defining the form of ingredients that have not undergone any extensive industrial processing, ie the physical form that contains the “original form of the ingredient”. ”(AAFCO, 2013). As a result, there is a growing trend for pet foods that contain more whole ingredients, such as meat instead of meat meal, whole grains instead of refined grains, and fruit and vegetable inclusions (Lummis, 2012).


The theory of beneficial effects of whole ingredients on health is described in the concept of so-called food synergy. Food synergy is based on the claim that the action of the food matrix (ie all ingredients naturally occurring in food) is greater or different from the effects of the individual food ingredients (Jacobs et al., 2009). It follows from the idea that we do not have complete knowledge of the composition of foods and some health effects may result from unidentified or underpriced ingredients. In this way, whole ingredients can provide health benefits that individual fractionated ingredients or individual nutrients cannot provide. Although the concept of food synergy may not be well known to consumers, the concept of whole health benefits has probably contributed to the interest of pet owners in natural pet food, and thus to the increased demand for whole raw materials in pet food.


The health benefits of phytonutrients from fruits and vegetables in humans are an example of food synergy. Epidemiological studies in humans indicate an association between fruit and vegetable intake with a lower risk of cardiovascular disease in women (Liu et al., 2000). A study in the human population has shown that the consumption of phytonutrient-rich foods as measured by the phytonutrient index reduces weight gain and adiposity (Mirmiran et al., 2012) and the risk of metabolic syndrome (Bahadoran et al., 2012). Rodent and in vitro models have demonstrated the positive effects of fruit food synergy on antiproliferative and anticarcinogenic activities (Jacobs et al., 2009). The incidence of drug-induced mammary tumor in rats was reduced more by the use of whole apple than by fetal pulp alone (Liu et al., 2005). Similarly, whole pomegranates had greater in vitro antiproliferative effects than some of their individual components (Seeram et al., 2005). Importantly, as fruits and vegetables and their ingredients are incorporated into pet food, further research is needed to understand the potential impact on pet health and well-being and the effect of processing on the stability of phytonutrients (Tiwari and Cummins, 2013).


Whole grains are added to pet food to obtain digestible carbohydrates and fiber (de Godoy et al., 2013). The effects of whole grains on animal health and welfare have not yet been thoroughly evaluated. Interestingly, however, whole grains have higher concentrations of many nutrients, including fiber, vitamins, minerals, and phytonutrients, compared to refined grains (Okarter and Liu, 2010; Jonnalagadda et al., 2011). For example, nutrient analysis of whole brown rice and brewer's rice used in pet food revealed higher (P <0.05) concentrations of ether extract of fat, crude fiber, phosphorus and potassium in whole brown rice compared to brewer's rice (Table 1). This may seem irrelevant given that the dietary composition of pet food is designed to take into account all the nutrients needed, especially if similar nutrient concentrations can be achieved with supplementary fiber and synthetic vitamins and mineral sources. However, as with fruits and vegetables, whole grains contain many unique phytonutrients. Recent studies by Forster et al. (2012a) demonstrated excellent digestibility and acceptability in dogs fed a dry extruded diet when wheat and corn were replaced with 25% boiled bean powder while controlling macronutrients and micronutrients. In addition, research has shown a positive effect on weight loss therapy in overweight and obese dogs (Forster et al., 2012b). In addition, in humans, the consumption of whole grain crops is associated with a lower risk of certain cancers, such as colon cancer. Phytonutrients such as ferulic acid are involved in the mechanism of this lower risk (Jonnalagadda et al., 2011).

The trend to include more whole ingredients in pet food has also led to an increase in the inclusion of crude animal protein products as opposed to ultra-processed animal protein products. Products can have a wide range of nutritional variability, which depends on the processing of the product. For example, a feed from an ultra-processed poultry product, including feathers and heads, had a more variable nutrient content than a pure poultry product that did not contain feathers or heads (Dozier et al., 2003). In a study using cocks to measure true AA digestibility, ultrasound animals usually had lower AA digestibility than raw animal products, with lamb meal showing the worst AA digestibility and pig liver (raw animal product) having the highest AA digestibility rate (Cramer et al., 2007). Ingredient supplier handling, processing and preservation significantly contributes to the variability in the nutritional value of animal products (Parsons et al., 1997), and therefore the ingredient supplier's procedures may be more important than the type of ingredient (ie raw vs. ultra-processed) in assessing quality or nutritional value of animal products.


Processing of ingredients and products

Processing can have a positive or negative effect on the nutritional value depending on the processing method and the measured results. For example, the degree of gelatinization of wheat starch is positively associated with in vitro digestibility and plasma glucose and insulin response in rats (Holm et al., 1988), indicating increased bioavailability of digestible carbohydrate by processing. In addition, the degree of gelatinization of starch and reactive lysines in dog food increases with increasing extrusion temperature up to 150 ° C compared to untreated raw material (Lankhorst et al., 2007). In contrast, increasing heat treatment time during canning of cat food has been associated with a decrease in the actual digestibility of AA ileum in rats (Hendriks et al., 1999). Higher drying temperatures (200 ° C) of extruded dog food led to lower lysines, reactive lysines, reactive ratios to total lysine ratio, linolenic acid and linoleic acid concentrations compared to lower drying temperatures (<160 ° C) in 4 mm granules (Tran et al., 2011). These examples of processing affecting the quality and nutritional value of an ingredient or final product emphasize the importance of quality control results in the selection of ingredients and processing of the final product.


The processing method also affects the nutritional value by influencing the moisture content of the final product. From a nutritional point of view, foods with a moisture content similar to animal prey better matched the philosophy of natural nutrition of domestic animals compared to dry foods. Although there is limited evidence to demonstrate the health benefits of high dietary intake in dogs, effects on urinary tract health and weight control have been demonstrated in cats. Feeding a diet containing 73% moisture reduced (P <0.05) the relative saturation of calcium oxalate from 1.14 ± 0.21 compared to 6 (2.29 ± 0.21) and 53% (2.06 ± 0.21). ) and reduced (P <0.001) specific gravity from 1.036 ± 0.002 compared to 6, 25 and 53% diets with humidity (1,052–1,054 ± 0.002) while increasing (P <0.001) the total water intake of cats to 144 , 7 ± 5.2 ml compared to diets containing 6, 25 or 53% moisture (98.6–104.7 ± 5.3 ml; Buckley et al., 2011). Another study found that cats consumed less (77 ± 10.8 vs. 86 ± 18.4 g / d; P <0.05) by ingesting ad libitum 40% of a hydrated diet compared to a dry diet with 12% moisture after weight loss; , with a trend to obtain less BW (312 ± 95.9 g vs. 368 ± 120.7 g; P = 0.28) and increase their activity level (P <0.001; Cameron et al., 2011). Although these findings may be specific to the diet being evaluated, due to the ubiquitous nature of urinary-related syndromes in cats, the potential health benefits of feeding pet food with higher moisture content (eg pasteurized / chilled, raw, frozen or canned) are usually they contain 70 to 85% moisture.


There are reports in the literature evaluating the digestibility of raw food in cat species, which have been discussed above. Kerr et al. (2012) evaluated the performance of extruded cat food versus raw or cooked beef food. These researchers found that the apparent total digestibility is greater (P <0.001) in both raw and cooked beef than in extruded diets. There were no differences in apparent digestibility between the raw and cooked beef diets. The differences observed in this study may be due to the composition and method of processing. Given the level of ingredient processing required before extrusion, it would be difficult to design a study using ingredients in the same physical form with and without extrusion.


The processing method is also an important factor in food safety. In terms of food processing, unpasteurized raw foods would be most in line with wild prey and would therefore be in line with the philosophy of natural pet nutrition. Protein quality plays a crucial role in the way feed is evaluated. The following 4 methods are most often used for protein evaluation:

Protein Efficiency Ratio (PER)

Biological Value (BV)

Net Protein Utilization (NPU)

Protein Digestibility Corrected Amino Acid Score (PDCAAS)


The biological value compares the nutritional value, or the totality of the various protein components. It measures the ability of a protein to supply the necessary amino acids, especially essential ones, and to supply them in the right composition. Protein has a high biological value when its content of essential and non-essential amino acids is balanced in terms of physiological needs. The better the amino acid spectrum of a given protein, the higher its biological value.


Biological value of proteins

Whole eggs 100

Chicken / turkey 79

Beef 78

Fish 70

Brown rice 57

Peas 50

Wheat 49

Soy 47

Maize 36

Beans 34


In general, full-value proteins include proteins of animal origin. In contrast, plant proteins are less valuable because they do not contain some amino acids in optimal amounts. For cereals it is lysine, for legumes methionine. The higher the biological value of a given protein, the better its use in proteosynthesis. The value starts with the number 100 and gradually decreases with decreasing protein quality. The egg has the highest biological value of 100, which sets a standard against which other proteins are evaluated. Raw materials such as animal fur or feathers contain a very high amount of protein, but their biological value is low.


According to AAFCO, meat is defined as "muscle tissue, including fat from slaughtered mammals in slaughterhouses, and is restricted to striated skeletal muscle or muscle parts contained in tongue, diaphragm, heart or esophagus without or with attached fat, skin parts, tendons, nerves and nerves. vessels which are a natural part of meat. They must be fit for human consumption. "


According to EU legislation, these are "All fleshy parts of slaughtered warm - blooded terrestrial animals fresh or suitably preserved, as well as all products and by - products resulting from the processing of carcases or body parts of warm - blooded terrestrial animals".



Influence of heat treatment on proteins of animal and plant origin


In the production of commercial feed, manufacturers must comply with hygiene regulations, which set temperature limits for their processing. In the production of extruded granules the minimum temperature is 90 ° C, in the production of cans 121 ° C.

Source: Commission Regulation (EU) No 142/2011


Proteins of animal origin undergo significant changes already at temperatures around 60 ° C. At this temperature, the native protein is denatured and the enzymes are destroyed. At higher temperatures, amino acids also break down. At a temperature of 110 ° C, about 5% of amino acids are destroyed, at a sterilization temperature of 120 ° C for 30 minutes, the losses are 8 - 15%, and at temperatures above 140 ° C 15 - 20%. Heat treatment of vegetable proteins improves their digestibility and nutritional value, especially for legumes. Heat treatment of proteins at temperatures below 100 ° C generally does not damage the nutritional or sensory value of the food.


Raw meat or fresh meat is used for the production of "wet fodder", but it is also increasingly used for the production of dry fodder (granules). The legislation defines fresh meat as follows: "Fresh meat" means meat, including meat packed under vacuum or in a protective atmosphere, which has not undergone any treatment other than chilling, freezing or quick-freezing. If we compare the content of meat in feed, it is important to realize that raw meat for dogs contains about 70% water (in meat meal only 7-10%). This means that raw meat is much less nutritionally concentrated than meat meal and therefore much more raw meat is needed to achieve the same amount in dry matter. For comparison: 10% of meat meal contains the same amount of protein and fat as 36% of raw meat.


However, it should be noted that due to processing in granules and canned food, there can be no fresh meat. In the production of cans it must be heated to at least 121 ° C and during the production of extruded granules it must pass a temperature of at least 90 ° C.


A study of the digestibility of crude protein and amino acids in protein sources used in commercial dog food, described in Animal Physiology and Animal Nutrition, 2017, states: “Whether raw meat makes food better is an interesting question. The results of our study show that, compared to poultry meal, raw meat does not improve either the amino acid composition or the digestibility of the feed. ” The study compared extruded granules containing only poultry meal with granules in which part of the poultry meal was replaced by raw meat. Raw chicken meat alone had a digestibility of 88.2%, poultry flour 80.9%. Contrary to expectations, it was found that the addition of raw meat to the granules did not improve their overall digestibility. The team found that both protein sources had digestibility values ​​between 80.3 and 81.3% after extrusion of the granules. Doc. Ahlstrøm believes that the reason for the reduced digestibility of the granules is the high temperature during extrusion. He sees the evidence in a disproportionate reduction in heat-sensitive amino acids during extrusion.


However, there are concerns about the safety of pathogenic bacteria that occur in many raw meats. Studies have shown that raw or undercooked animal sources can be contaminated with a number of pathogenic organisms, including Salmonella spp., Campylobacter spp., Clostridium spp., Escherichia coli, Listeria monocytogenes and enterotoxigenic Staphylococcus aureus (Freeman and Michel, 2001 LeJeune and Hancock, Joffe and Schlesinger, 2002; Stiver et al., 2003; Weese et al., 2005; Finley et al., 2006). In a cohort of 200 therapeutic dogs, the incidence of salmonella excretion in raw meat dogs was 0.61 cases / dog year, compared to 0.08 cases / dog year in dogs that were not fed raw meat (P <0.001; Lefebvre et al., 2008 ). This poses a risk of foodborne illness for pets eating contaminated food and for secondary transmission to humans, especially children, the elderly, and immunocompromised individuals (LeJeune and Hancock, 2001; Joffe and Schlesinger, 2002). In view of these health risks, the American Association of Veterinary Surgeons, the American Federation of Animal Hospitals and the US Food and Drug Administration have issued statements on practices for avoiding unsafe handling of raw foods (AAHA, 2011; AVMA, 2012a; FDA, 2013). The US College of Veterinary Nutrition has also approved a publication on the potential risks over the benefits of pets eating a raw meat diet (Freeman et al., 2013). In addition, a purely raw diet may pose a risk of metabolic disease depending on the parts of the animal used in the diet.



The pet food segment has grown in recent years due to consumer demand. Increased demand for these products has focused on convincing consumers that these products are high quality, safe, made from ingredients that fit an individual concept, and provide functional health benefits. AAFCO and FEDIAF have described different regulatory definitions of pet ingredients and products; however, most consumers perceive what should be considered natural based on personal experience, bias or preferences.

Given that there are currently no data on the impact of manufactured feed on pet health, some pet feeding companies are focusing on formulating a diet and ingredient based on teleological justification that dogs and cats should eat a diet similar to that of related wildlife. kinds. There are a number of research opportunities involving natural pet foods and natural diets to understand their effects on growth and performance, nutrient availability, digestibility, product safety, among other health and nutritional parameters. Future opportunities also include integrating sustainability with natural pet foods (Swanson et al., 2013).

The challenge will be to match consumer demand and provide pets with the best possible nutrition, while reducing the impact on the environment. With the growing trend of pet anthropomorphism and interest in ancestral or instinctive diet, it will be a great challenge to reconcile animal nutrition with the human food chain and the resulting high overuse of animal protein sources.






Nutrition and health impact - The nutrition and health impact assessment algorithm primarily assesses the content and proportion of nutrients together with the quality and quantity of the raw materials contained and the additives used. Source of protein (animal or vegetable origin), content of meat or animal by - products and suitability and quality of each raw material used in the feed and its composition. Each component of the feed is evaluated according to its usefulness. Natural and healthy raw materials increase feed ratings, while synthetic substances, fillers and controversial additives reduce ratings. The ratio of raw materials is also important. The score algorithm is calculated automatically on the basis of composition data and analytical nutritional data, which eliminates any manual intervention and guarantees the complete impartiality of the evaluation. We obtain composition data and analytical nutritional data from several independent sources, which we compare.

The composition means, for example, the following reference product composition: Lamb (35%, of which 20% dried, 15% boned), rice, chicken fat (preserved with a mixture of tocopherols), rice bran, dried apples, salmon oil (2%), dried chicken, brewer's yeast, collagen, crustacean shells [source of glucosamine] (210 mg / kg), cartilage [source of chondroitin] (150 mg / kg), fruit herbs (cloves, citrus, rosemary, turmeric - 120 mg / kg), mannan oligosaccharides (120 mg / kg), fructooligosaccharides (90 mg / kg), Mohave-Palmilie (90 mg / kg), dried chamomile (80 mg / kg), green-lipped mussels [glycosaminoglycans] (60 mg / kg), dried blueberries (50 mg / kg).

By additives are meant, for example, the following reference product composition: Vitamin A [3a672a] (15,000 IU / kg), Vitamin D3 [E671] (1,000 IU / kg), Vitamin E (α-Tocopherol [3a700]) (400 mg / kg) ), Biotin [3a880] (0,5 mg / kg), Choline chloride [3a890] (500 mg / kg), zinc and amino acid chelate, Hydrate [3b606] (70 mg / kg), iron and amino acid chelate, Hydrate [E1 ] (60 mg / kg), manganese and amino acid chelate, Hydrate [E5] (30 mg / kg), Potassium iodide [3b201] (0.5 mg / kg), copper and amino acid chelate, Hydrate [E4] (12 mg / kg) kg), Selenium [3b8.10] (0.2 mg / kg). Vegetable oil tocopherol extract [1b306], Ascorbyl palmitate [1b304] and rosemary extract.

By analytical nutritional data is meant, for example, the following reference product composition: protein 26.0%, fat 13.0%, fiber 3.0%, ash / ash 7.0%, phosphorus 1.1%, moisture 10.0%, omega-3 fatty acids 0.2%, omega-6 fatty acids acid 1.5%.


Other parameters - The algorithm for evaluating other parameters takes into account the price of the feed ration together with the country of origin and the impact on the environment. Independent laboratory verification of the composition and nutritional analytical data is also considered, together with the impact on animal welfare (possible brand and / or producer activities in this area). Another parameter is a clear, transparent and comprehensible declaration of product and manufacturer and country of origin data.

Total score


We combine the scores of all three areas above into an overall product score, with users seeing a breakdown of the individual factors that affect the overall score. The overall score, as well as its individual parts, may vary depending on the latest scientific knowledge concerning the whole chain of feed production and distribution. Petgroot feed scores are rated on a scale of 0-100%. As a result, a ranking is created in each category and each product is placed in it. This gives you the opportunity to compare and make better choices. At the same time, we have prepared a green - best / red - worst color orientation system for better orientation, which will differentiate all feeds in color.




The methodology for the evaluation of Petgroot pet food is developed in accordance with Commission Regulation (EU) 2017/1017 of 15 June 2017 amending Regulation (EU) 68/2013 on the catalog for feed materials and the 295th DECREE of 27 June 2017. October 2015 on the implementation of certain provisions of the Feed Act from the Collection of Laws of the Czech Republic.


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