Module.01. Nutrition Essentials. Module.01

Transcription

1 Nutrition Essentials Let s get started! We will learn about the 6 classes of nutrients as well as the energy requirements of dogs and cats. We will also look at the contribution that diet makes to a pet s overall health, and examine some of the key differences between dogs and cats with regards to optimal nutrition.

2 Table of Contents p01 - Basic Nutrients and their Function p02 - Energy p03 - Energy in Food p05 - Energy Requirements of Cats p06 - Energy Requirements of Dogs p07 - Energy Balance p07 - Condition Scores p09 - Classes of Nutrients p10 - Protein p14 - Fats p16 - Carbohydrates p16 - Dietary Fibre p17 - Vitamins p18 - Minerals p19 - Water p20 - Understanding dogs p20 - Understanding cats p22 - A Complete and Balanced Diet p23 - Optimal Nutrition p24 - National Requirement Guidelines p25 - Nutrient Guidelines Dogs p26 - Nutrient Guidelines Cats p27 - Appendix

3 Basic Nutrients and their Function Like all living creatures, dogs and cats require food for survival. Food may be defined as any substance that contains essential body nutrients, that when ingested is assimilated by the body to produce energy, stimulate growth and maintain life. It is the nourishment in food that provides energy to allow muscles to move and the pet to maintain body heat. The nourishment in food also provides the materials for growth and repair of body tissues and enables body processes to occur. The components of food that have these functions are called nutrients and the foods or food mixtures that are actually eaten are referred to as the diet. Any nutrient that is required by the animal and cannot be made or formulated in the body is called an essential nutrient and must be obtained from a complete and balanced diet. If any essential nutrient is lacking or present in an insufficient quantity in the diet, then the diet as a whole must be considered unbalanced and inadequate. Long term feeding of a nutritionally inadequate diet can result in poor performance or disease. 01

4 Energy In addition to providing specific nutrients, food also supplies energy. Energy is a fundamental requirement of all living things and provides the power for the body s cells to function. The energy content of the diet is derived from protein, fat and carbohydrate and the amounts of each of these nutrients in a food will determine its overall energy content. Energy of the Diet = protein + carbohydrate + fat Water has no energy value, so the higher the water content of a food, the lower its energy concentration. 02

5 Energy is expressed in terms of kilocalories (kcal), where 1 kcal is defined as the quantity of heat required to raise the temperature of 1 kg of water by 1 degree Celsius. A more recent convention is to express energy in terms of Joule or Kilojoule (kj), where 1 kcal equals kj. Energy intake must be carefully regulated and maintained at a level close to the pet s requirements. When the calories from food exceeds the energy needed this can lead to obesity or, in some young dogs, growth abnormalities, especially if maintained over long periods. Too little intake of calories results in poor growth in young animals and weight loss in adults. The true energy requirement needed by a pet may vary by as much as 25%. This is due to the wide variation between breeds, age, activity levels, physiological state (eg. growth, pregnancy, lactation), body composition and to environmental factors. It must be emphasised then that the feeding guides found on pet food packaging are guides only. One must also monitor the pet s overall body condition, and relate that to the amount of pet food that is fed, so as to maintain optimal body condition. It has been scientifically proven that maintaining large breed dogs at a lean body mass index over their life time, can extend thier life by up to 2 years. Energy in food The Gross Energy (GE) of a food is the amount of chemical energy released when that food undergoes complete combustion in a bomb calorimeter. When the food is ingested, the majority of GE is utilised by the pet but some is lost in faeces. When further losses of energy in urine and gas are taken into account, the result is called Metabolisable Energy (ME). This is the energy available to the pet for metabolism. The energy content of a pet food is most commonly labelled on pack as ME, and expressed as kcals per 100g. That is, the number of kcals of energy the pet obtains for every 100g of the pet food that it consumes. The ME content of different foods, depends both upon their composition and upon the animals that consume them. Individual cats and dogs will show differences in digestibility values when fed the same food. The energy density of the diet must be high enough to enable the dog or cat to obtain sufficient calories to maintain energy balance, as well as being matched to other specific nutrients such as protein. Energy density is the main factor determining the volume of food eaten by a pet each day and therefore the amount of each nutrient taken in by that pet. Nutrient requirements are usually expressed in terms of the ME concentration so that the values are applicable to any type of food or diet regardless of its water content, nutrient content or overall energy value. 03

6 Let s take a practical look at the energy content of some foods- fresh lean meat and a dry food. We will use the following formula to work out what contribution to the total ME, is made by the protein, fat and carbohydrate content of each food. 1g of fat will produce 8.46Kcal of ME 1g of carbohydrate will produce 3.5Kcal of ME 1g of protein will produce 3.5Kcal of ME In the case of prepared pet foods, the amount of protein and fat in the product, will be shown on pack. To calculate the carbohydrate content, we use the following formula: % Carbohydrate = (% Protein + % Fat + % Moisture + % Ash + % Fibre) Fresh lean meat has the following typical analysis, per 100g: Protein 20.3g Fat 4.6g Carbohydrate 0.5g Therefore: 20.3g of protein will produce 20.3 x 3.5 = 71.05kcal/100g 4.6g of fat will produce 4.6 x 8.46 = 38.92kcal/100g 0.5g of carbohydrate yields 0.5 x 3.5= 1.75kcal/100g TOTAL: 112kcal/100g of energy from fresh lean meat. A selected Super premium dry dog food has the following typical analysis, per 100g: Protein 26.0g Fat 15.0g Carbohydrate 35.0g Therefore: 26.0g of protein will produce 26.0 x 3.5 = 91.0kcal/100g 15.0g of fat will produce 15.0 x 8.46 = 126.9kcal/100g 35.0g of carbohydrate will produce 35.0 x 3.5 = 122.5kcal/100g TOTAL: 340.4kcal/100g energy from this super premium dry dog food. As you can see from this example, the prepared pet food provides around three times the energy that fresh, lean meat does. 04

7 Energy Requirements The daily energy requirement of a cat and dog is calculated according to their bodyweight. As energy requirements do not have a linear relationship with bodyweight, a mathematical formula, derived from scientific evidence, must instead be applied. It is important to note that the formulae apply to healthy adult pets. To calculate the daily energy requirement for the average adult cat, the following equation must be applied to the body weight: Cat energy requirement = 77.6W (where W is the cat s bodyweight in kg) 05

8 The daily energy requirement for dogs is based on the level of activity. Low Activity Less than 1 hour per day, eg walking on the lead. Energy = 95W 0.75 Moderate Activity 1-3 hours per day, eg playing off the lead. Energy = 110W 0.75 High Activity Over 3 hours per day, eg working dogs, agility. Energy = 125W 0.75 Where W is the dog s bodyweight in kg In addition to bodyweight, there are a number of factors that may affect the energy requirement of a pet including: Body condition, Environmental conditions, Life stage & health status, Hair & coat type, Neuter status, Breed & individual differences Level of activity, Different formulae exist for puppies, kittens, gestating/lactating mothers or overweight pets (See Appendix 1 on Page 30). This is because each life-stage has different energy requirements, to what is needed in adult maintenance. For example, puppies and kittens require additional energy for growth and gestating/lactating mothers require additional energy for foetal development and milk production. Senior dogs may require less energy than for adult maintenance, and generally should be fed according to the low activity guideline for dogs. Energy requirements do, however, also vary with the body type. Feeding studies in dogs have shown that breed conformation affects energy requirements. For example, Newfoundlands need less than the predicted amounts of energy, whereas Great Danes need more. These two breeds have approximately the same body weight but have very different body composition, hair type (coat) and shape. These basic energy requirements may then be modified according to the animal s life stage and state of health (or disease), level of activity and environmental conditions. In general, dogs and cats eat to meet their energy requirements. Since energy content is one of the main determinants of the amount of food eaten, then all other nutrients must be matched to energy to ensure an adequate intake of these nutrients. 06

9 Energy balance An animal is said to be in energy balance when its intake equals its output, with the result that the level of energy stored in the body does not change. In the adult animal, energy is stored predominantly as fat and these deposits are easily observed in the obese animal. When energy intake is too low the body breaks down its own fat and muscle tissues to meet its energy needs. As the body s stores are gradually depleted the animal becomes thinner and its bodyweight decreases. Energy balance is achieved through the matching of input and output over long periods. A very small imbalance maintained over a long period of time will cause obesity (if too much energy is taken in) or wasting (if not enough). For example, if a 35kg dog requires about 1,600 kcal per day, and the dog is fed an additional 100 kcal/day (about 25 g of dry dog food), then this could result in an increase of 2-3 kg bodyweight if maintained over a year! Condition Scores As mentioned previously, feeding guides on pet food packaging are guides only. One must also monitor the pet s overall body condition, and this is achieved by performing a Condition Score assessment. A review of various animal physiques has led to the development of the Body Condition Guide. Body Condition assessments are a convenient way to consistently and objectively assess the body condition of dogs and cats. Body Condition assessments are an excellent way to determine if a pet s food intake is appropriate, and are a very important visual factor in assessing overall health and general well being. As we know, a feeding guide is exactly that - a guide, as energy requirements can vary up or down by 25% depending on the life stage, coat type, body conformation, age, environmental factors and activity levels. The Body Condition guide is a useful tool for teaching owners/clients how to monitor their pet s physique. To assess the Body Condition of a dog or cat, one should observe the animal from both a side-on view and an aerial view. The animal should be examined to see how prominent the rib cage and spinal column are, and how easily these features can be felt. Animals are then given a Body Condition Score of 1 through to 5. A Score of 1 indicates an emaciated state, and a Score of 5 indicates that the animal is obese. A Score of 3 indicates ideal Body Condition. The charts on the following pages explain Body Condition Scores further. 07

10 Feline body condition guide image source: The five point body condition scoring system for cats. Canine body condition guide image source: The five point body condition scoring system for dogs. 08

11 Classes of Nutrients Let s now explore the 6 major classes of nutrients. They are: PROTEINS FATS CARBOHYDRATES VITAMINS MINERALS WATER These nutrients are all required in the diet in the correct amounts and proportions to ensure optimal health. It is important to note that a pet s requirements for all of these nutrients vary throughout the different life stages. Puppies and kittens have a different nutritional requirement to adult and senior pets. Let s look at the some of the individual nutrient components in more detail. 09

12 Protein Protein is required during normal maintenance for: Tissue building and repair (muscle, hair, skin) Regulation of metabolism (hormones eg. insulin and enzymes eg. protease) Combating disease (antibodies) Supplying energy Additional protein is needed during periods of growth, gestation, lactation, physical activity and for the repair of damaged tissue, such as for wound healing or recovery from surgery. One of a pet s biggest demands for protein is for the maintenance of skin and coat health, which can use 30-35% of dietary protein. Proteins are made up of hundreds of single units of amino acids in predefined chains that determine their roles within the body. For example, these units represent the amino acids that make up a dog hormone protein. There are 20 different amino acids in animal proteins. Of these, there are 11 amino acids that must be supplied in the diet of cats, and 10 that must be supplied in the diet of dogs. These amino acids are termed essential amino acids meaning that they cannot be produced by the body and so must be consumed via the diet. In addition there are two amino acids that are conditionally essential, tyrosine and cysteine, whether or not these are required in the diet depends on on the availability of other amino acids - respectively phenylalanine and methionine. isoleucine leucine valine histidine lysine?? phenylalanine methionine taurine arginine tryptophan threonine humans, cats and dogs cats and dogs cats only Essential amino acids in dogs, cats and humans 10

13 A deficiency in any of the essential amino acids can cause health problems. The absence of any of the essential amino acids from the diet stops the synthesis of essential proteins. As a consequence, the pet then breaks down its own body tissues to provide the required amino acids, seriously comprimising health. The other amino acids are termed non-essential because they can be synthesised by cats and dogs. Amino acids are connected in a variety of sequences, with each combination resulting in proteins with specific characteristics and functions. Think of them like a string of beads. When an animal eats protein, enzymes break the protein down into the amino acid building blocks. It is only in this form that absorption into the bloodstream can occur through the gut. protein: a chain of amino acids intestinal lumen brush border intestinal mucosa immunity Protein metabolism enzymes (proteases) gradual absorption of amino acids construction messages regeneration transport Once absorbed, most of the amino acids are reassembled in a different order to create the specific protein structures that the body needs. Excess amino acids are not stored in the body. They are broken down in the liver releasing energy and at the same time producing urea, which is excreted through the urine. Protein can be obtained from both animal or plant origin sources, such as egg, milk, meat (including organ meats), fish, legumes and cereal glutens. Deficiency of protein can result in poor growth, loss of bodyweight and poor coat condition. 11

14 Not all Proteins are created equal! Due to the differing amino acid structures of different proteins, not all proteins provide the same nutritional quality. To differentiate between proteins, we need to look at their protein quality. The ability of a protein to be used by the body and its amount of usable amino acids is summarised as protein quality (also known as biological value). Egg has the highest biological value and sets the standard for which other proteins are judged. Egg has a biological value of 100. Two things determine protein quality: 1. Amino acid type. This refers to the particular amino acids that are present in the protein food source. As we know, there are a number of essential amino acids that cannot be made by cats and dogs so they must be present in the diet. The body can make the remaining amino acids, providing a balanced diet is fed. In this example, if a dog ate some meat and some feather meal (both of which are protein sources), the body then tries to digest these proteins. Enzymes break down the proteins, into individual amino acids. The amino acids are then reconstituted by the body, and are used for many functions, such as to manufacture hormones. To create the dog hormone in the above example, the body needed amino acids only found in the meat protein (not the feather meal protein). Meat Individual amino acids Consumed by dog Digested Feather meal Dog hormone NB: Uses individual amino acids included in meat but not feather meal in this example. 2. The digestibility of the protein. Digestibility is the amount of protein that is absorbed into the body and not lost in faeces. 100g 85g 15g The digestibility of a food is a measure of the availability of its actual nutrients to the animal. If you analyse a food, it might be very high in a nutrient. A leather jacket is very high in protein, but it is only the portion of nutrients that are actually absorbed from the gut that have any true nutritional value. In the case of the jacket the digestibility of the protein would be nil. Therefore, you can see that a high amount of protein is not necessarily best. You need to consider the overall protein quality. 12

15 This chart compares the protein content and digestibility of various foods: FOOD DIGESTIBILITY Corn 54% Yeast 63% Soy 75% Milk 89% Fish 75% Wheat 60% Organ Meat 90% Muscle Meat 92% Rice 72% Egg White 100% PROTEIN CONTENT 9% 45% 31% 3.5% 20% 10-12% 20% 20% 7% 11% image source: Leading The Way in Pet Nutrition, Mars Petcare, Protein digestibility of pet food also varies, depending on the product formulation. Practical comparisons between different foods should go beyond a cursory glance at the overall protein level given on the label to take into account the source of the protein and how this affects the amino acid profile and its digestibility. Quality is more important than quantity! 13

16 Fats Humans are often obsessed with the fat content of their food. As a general rule, fats are a good thing for cats and dogs and in many instances reducing fat intake can be detrimental. The differences between one fat and another are mostly the result of different combinations of fatty acids in each. Fatty acids are termed essential when they cannot be generated within the body. The omega-3 and omega-6 groups of fatty acids represent the key essential fatty acids in mammalian nutrition. Dietary sources of fat include vegetable oils obtained from seeds and nuts such as flaxseed, sunflower and linseed oils, as well as animal fats such as fish oils and poultry fat. What do fats do? Fats (also called lipids) contain approximately twice as much energy per gram than protein or carbohydrates. They provide a useful source of calories and are therefore useful in the production of growth diets, working dog diets and foods for lactating bitches and queens. Fats also play a key role in increasing the palatability of foods, particularly of dry foods. A very important function of fat is as a provider of fatty acids, particularly the essential fatty acids (EFA), and as a carrier for the fat-soluble vitamins A, D, E and K. Fatty acids are involved in many aspects of health, including kidney function and reproduction. They are essential components of cell membranes and they are involved in the process of inflammation within the body. Concentrated energy source Palatability Regulation of cell membrane enzymes Source of essential fatty acids Functions Carriers of vitamins (A, D, E, K) Cell membrane functionality Insulation and protection of organs image source: Petcare School, Mars Petcare

17 Omega-3 fatty acids include eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and alpha-linolenic acid (ALA). maturation of the nervous system in young animals and combating cerebral aging in older animals intestine joints cell oxygenation effort (muscle) omega-3 fish oils skin anti-inflammatory roles kidney Role of Omega-3 fatty acids in the body Omega-6 fatty acids include arachidonic acid (ARA) and linoleic acid (LA). Linoleic acid is an essential fatty acid for dogs (who can make arachidonic acid from linoleic acid). Cats however are unable to carry out this conversion step, therefore both arachidonic acid and linoleic acid are essential fatty acids for cats. reproductive function omega-6 vegetable oils and some unsaturated animal fats skin health and hair quality skin Role of Omega-6 fatty acids in the body Deficiency of fatty acids can result in fat soluble vitamin deficiency, poor skin and coat condition, loss of bodyweight and impaired fertility. Excess may lead to weight gain, which can in turn predispose the pet to conditions such as diabetes, joint disorders and pancreatitis. 15

18 Carbohydrates Dogs and cats do not have an essential requirement for carbohydrates in their diet, although carbohydrates are a useful major source of energy in many pet foods. Sugar, starch and fibre are all examples of carbohydrates. The most common sugar derived from the breakdown of starch is glucose, which is the major form in which energy is carried to the body s cells by the blood. Glucose is the preferred energy source for the brain, nervous tissue and red blood cells. Carbohydrates can therefore serve as a convenient source of glucose or blood sugar. Carbohydrate levels are usually higher in dry pet food than in wet pet food. Pet foods vary in the amount of carbohydrate to meat ratio, however digestibility is based on the quality of the carbohydrates, how they are processed and meats used, not the quantity of the carbohydrate. Dietary sources of carbohydrate include cereals, grains, sugars, fruits and vegetables. Dietary Fibre Dietary fibre is a term that covers a wide variety of soluble and in-soluble carbohydrates with different effects. Dietary fibre, or roughage, is found in the cell walls of plants. These materials generally do not get digested by the digestive enzymes of dogs or cats, and so pass through the digestive tract relatively unchanged. Dietary fibre may provide bulk to the faeces, help regulate bowel movements and also help to prevent constipation or diarrhoea. Other fibres can be broken down in the bowel by the resident gut bacteria. These fibres help to maintain gut health through their beneficial effects on the activity of organisms in the large bowel. Dietary Fibre: Assists digestive health Increases faecal bulk and prevents constipation May promote colonisation by beneficial gut bacteria Fibre is not broken down by the body s enzymes (like proteins or fats are) but rather by intestinal bacteria. The intestinal cells then use the products of this break down directly as a food source. 16

19 Vitamins Vitamins are organic compounds that help to regulate body processes. Most vitamins must be supplied in the diet on a regular basis. There are 13 vitamins that are classified as either fatsoluble (vitamins A, D, E and K) or water-soluble (B-complex vitamins and vitamin C). Essential water soluble vitamins - key functions Essential fat soluble vitamins - key functions B1 (thiamin) nervous system Vitamin A vision, skin B2 (riboflavin) skin Vitamin D calcium and phosphorus metabolism B3 (niacin) skin, cell energy Vitamin E antioxidant B5 (pantothenic acid) growth, skin Vitamin K blood clotting B6 (pyridoxine) cell energy B7 (biotin) skin, hair B9 (folic acid) formation of blood cells B12 (cobalamin) formation of blood cells choline synthesis of phospholipids The fat-soluble vitamins are stored within the body to a much greater extent than water-soluble vitamins. The risk of accumulation and toxicity is therefore far greater with the fat-soluble vitamins. Supplementation with cod liver oil or liver (high in vitamin A), for example, can lead to signs of toxicity when fed in addition to a complete and balanced diet. Water-soluble vitamins tend to be excreted through the urine therefore toxicity is unlikely to be an issue. Dietary sources include cereals, vegetables, nuts and oils, meat and offal. 17

20 Minerals Minerals are inorganic nutrients within the diet. When a food is analysed for energy, all nutrients other than minerals are removed. The remaining material is made up of dietary minerals, and is often referred to collectively as ash. Minerals may be divided into macro minerals (which are required in relatively large amounts) and trace elements or micro minerals (which are required in relatively small or trace amounts). Minerals may be naturally occurring within pet food ingredients, or may be added as purified salts eg iron sulphate, zinc oxide and calcium iodate. Although required in relatively small amounts, minerals have very important health functions. Essential macrominerals - key functions Calcium ossification of bones Phosphorus energy transfer Potassium cellular ion balance Sodium cellular ion balance Magnesium sensory impulses Chloride acid base balance Essential microminerals - key functions Iron synthesis of haemoglobin within red blood cells Zinc skin and coat health Manganese formation of cartilage and skin Copper blood synthesis of skin pigments Iodine functioning of the thyroid gland Selenium antioxidant Minerals can be toxic however, if fed in large quantities. Iron, copper and zinc are important nutrients, but can be toxic if fed in excess. Mineral excess can also cause skeletal disorders in growing pets. Mineral deficiencies can result in a poor coat condition, poor growth and reproductive issues. Dietary sources include cereals, vegetables and meats. 18

21 Water This is often the forgotten nutrient! We are mostly composed of water, which makes up around 50-60% of an adult s bodyweight. Newborns are generally composed of around 75% water! How much water does a pet need per day? A dog s water requirement is 60ml/kg/day. A cat s water requirement is 50ml/kg/day. The daily water intake of any animal will depend on a number of factors including the moisture content of the food it is eating, the environmental temperature, it s level of activity and it s physiological state. A plentiful supply of fresh drinking water should therefore, always be available. Life may continue for weeks in the absence of food but only for a few days or even hours when water is not available. A 10% loss of water will cause serious illness and a 15% loss will lead to death if not quickly replaced. Water has many essential functions such as: To replace water losses from the body through urine, faeces and respiration, as well as in secretions such as milk. water in respiration thirst regulation no sweating water in excrement Required for all body cells and most metabolic processes. As a carrier of the water-soluble vitamins. Helps to regulate body temperature. Water is an ideal medium for transporting nutrients and waste through the body. water, drink and food metabolic water water, in urine water utilisation in the dog Water is taken into the body in several forms: as fluid drunk such as water, as a component of food ingested or as metabolic water (that released during the breakdown of protein, fat and carbohydrate). Signs of dehydration include neck skin that stays tented when gently pinched, lethargy or a dry mouth. Cats have a reputation for drinking little because they are descended from desert animals and are able to concentrate their urine. However, if that concentration is too high, it increases the risk of crystal and stone formation within the urinary tract. An abnormally high intake of water may be a sign of diabetes or kidney disease in pets. 19

22 Differences Between Dogs & Cats Understanding dogs ?? The dog is able to consume a more omnivorous diet. The dog is classified in the Order Carnivora (carnivores). It is well adapted for eating meat. 1. Sense of smell is up to 10,000 times more sensitive than humans teeth designed for cutting, tearing and grinding. The enamel of dogs teeth is approximately five times thinner than that of humans 3. Fewer taste buds than humans 4. Limited salivary amylase (little carbohydrate predigestion). Saliva ph is more alkaline than humans 5. A very expandable stomach designed to cope with large meals 6. Stomach ph is more acidic than in humans for digestion of bones and destruction of harmful bacteria 7. Transit time through the intestine is hours compared with 30 hours to five days in humans 8. Bacterial fermentation takes place in the large intestine Anatomy of the canine digestive tract Understanding cats The cat is classified in the Order Carnivora (carnivores). It is well adapted for eating meat. The cat is an obligate carnivore and therefore must have meat in its diet teeth, all of them sharp and designed for cutting and tearing. No sideways movement of the jaw. The enamel of cats teeth is approximately ten times thinner than that of humans 2. Cats have even fewer taste buds than dogs. They have nonfunctional sugar taste receptors 3. No salivary amylase (no predigestion of carbohydrate) 4. The stomach is designed for many small meals spread throughout the day 5. Stomach ph is more acidic than humans for digestion of bones and destruction of harmful bacteria 6. Transit time through the intestine is hours compared with 30 hours to five days in humans 7. Small intestine well suited to digesting proteins and fats. Cats are not able to down-regulate protein digesting enzymes and therefore need a protein rich diet 8. Bacterial fermentation takes place in the large intestine Anatomy of the feline digestive tract 20

23 Cats are not small dogs! Cats have a number of unique nutritional requirements compared to dogs, including: A high protein requirement. They need pre-formed Taurine in the diet as they cannot synthesise their own like dogs can. Taurine has many functions within the body including being needed for immune system and heart health, vision and reproduction. There needs to be about twice as much taurine in wet diets than dry diets. This is because taurine is part of the bile salts which are excreted into the small intestine and pass through to the large intestine where normally the taurine is absorbed by the body and recycled. But in cats fed wet diets, the bacteria in the large intestine are more active at breaking down the taurine for their own use, before the body can reabsorb it. Therefore more has to be put into the diet to compensate. They need a regular supply of Arginine (an amino acid). In the absence of Arginine, cats rapidly develop clinical signs of ammonia intoxication if they ingest protein, as arginine is required for the breakdown of toxic by-products of protein digestion. They need pre-formed Arachidonic Acid (an Omega 6 Fatty Acid) in the diet as they cannot synthesise their own from Linoleic Acid (like dogs can). They need pre-formed Niacin (Vitamin B3) as they have a very limited capacity to synthesise this (dogs have more capacity for this). They need pre-formed Vitamin A in the diet as they cannot synthesise their own from Beta- Carotene like dogs can. As you can see there are some key nutritional differences between dogs and cats. These factors must be taken into account when formulating the ideal diet for each species. The skulls of dogs and cats It is interesting to also review the different skull and teeth shapes of dogs and cats. Although the dog is a member of the order Carnivora, in a nutritional sense it is more accurately defined as omnivorous and is able to use a wide variety of plant and animal material in its diet. Unlike the cat, the dog can survive on a diet composed entirely of vegetable material, although a diet based on animal tissue is likely to be preferred. Cats are also a member of the order Carnivora, however as we have seen have very specific nutrient requirements that mean it is an obligate carnivore. Cats cannot be made vegetarians! Cats have evolved with teeth designed for cutting and tearing, and they have a relatively short gut length, so they need food that is easily digested. canine skull feline skull 21

24 A Complete and Balanced Diet A diet that is complete and balanced will supply all of the key nutrients and energy needed, in the right proportions to meet the daily needs of the animal at its particular life stage. Nutrient and energy content are therefore important considerations but other related factors include digestibility and palatability of the food. Animals eat to satisfy their requirement for energy, so it is important that a pet food balances the key nutrients to the energy content of the diet. Therefore, providing the correct quantity of energy also ensures an appropriate intake of essential nutrients regardless of whether the pet food format is wet, dry or semi-moist. In times of higher need (such as in gestation or lactation) animals will take in all key nutrients in greater amounts when they increase the amount of food eaten to meet their energy demands. 22

25 It is important to note that meat alone is not a complete and balanced diet. This is especially important for puppies, and we will examine this more closely in a later module. A good quality commercial diet ensures that the feed is complete and balanced, and that the key nutrients are balanced to the energy content of the diet. Optimal Nutrition Manufacturing a complete and balanced diet for cats and dogs is a highly complex process. It requires expertise at all stages of production from sourcing raw materials to blending the vitamin and mineral mixes, understanding the role of processing for each pet food format and knowledge of the nutrient and energy requirements of cats and dogs. health minimum requirement maximum requirement Recommended daily nutrient intake. Nutrient requirements are bounded by a minimum and, in some cases, a maximum value. These have been determined through many years of research. deficiency intake excess The amount of nutrient needed in the diet must lie between the minimum and maximum requirement. The main criteria for what constitutes a complete and balanced diet can therefore be summarised as: The content of each nutrient must be between the minimum and maximum requirement. Each nutrient must be present in the correct ratio to the energy content of the diet. Each nutrient must be at the correct ratio to other nutrients (where appropriate). Each nutrient must be in a form that is useable by the animal for which the diet is made. Optimal nutrition is therefore not just about having high amounts of particular nutrients in the diet. It is essential that the right nutrients are supplied in appropriate amounts, and in a form that is easy to digest and use by the body, to promote optimal health and well being. 23

26 National Requirement Guidelines There are a number of different bodies that produce guidelines for the nutrient requirements of cats and dogs. These bodies base their recommendations on the vast quantity of information that exists in the scientific literature. All of these bodies are broadly similar in their guidelines, but they may vary slightly - often due to differences in interpretation of the scientific evidence. National Research Council (NRC) The NRC committee consists of key academic experts in the field of companion animal nutrition who define the nutrient requirements of cats and dogs. The NRC guidelines influence all other nutritional standards - although there are examples of differences between the NRC and other nutritional agencies. Association of American Feed Control Officials (AAFCO) AAFCO guidelines are written by invited experts from the industry and academia. Compliance with these guidelines is a legal requirement in most states of the USA. Although AAFCO produces an official publication every year, it doesn t necessarily update the information each time. The Australian Standard for the Manufacturing and Marketing of Petfood, AS5812, references AAFCO nutrient guidelines (see Module 3). WALTHAM WALTHAM produces nutrient specifications for MARS using external and internal knowledge. These specifications are known as MARS Petcare Essential Nutrient Specifications (MPENS). They are solely produced for internal use by Mars Petcare Associates and are updated every two years with the latest scientific knowledge. Every essential nutrient has a specified range that all MARS products must meet to make a Complete and Balanced claim. This is in addition to any industry requirements on Complete and Balanced for a particular pet food market. 24

27 As an example, AAFCO Nutrient Specifications for dog food for the different life stages (per 1,000kcal Metabolisable Energy): Dog AAFCO 2006 Adult AAFCO 2006 Reproduction AAFCO 2006 Growth Nutrients Unit RA SUL RA SUL RA SUL Protein g Arginine g Histidine g Isoleucine g Methionine g Methionine-Cysteine g Leucine g Lysine g Phenylalanine g Phenylalanine-Tyrosine g Threonine g Tryptophan g Valine g Fat g Linoleic acid g Arachidonic Acid g Linoleic + Arachidonic Alpha Linolenic Acid g EPA/DHA g Calcium g Phosphorus g Ca/P ratio Magnesium mg Sodium g Potassium g Chloride g Iron mg Copper mg Zinc mg Manganese mg Selenium µg Iodine mg Vitamin A IU Vitamin D IU Vitamin E IU Vitamin K mg Thiamin B1 mg Riboflavin B2 mg Pyridoxine B6 mg Niacin mg Pantothenic Acid mg Cobalamin B12 µg Folic Acid µg Biotin µg Choline mg

28 As an example, AAFCO Nutrient Specifications for cat food for the different life stages (per 1,000kcal Metabolisable Energy): Cat AAFCO 2006 Adult AAFCO 2006 Reproduction AAFCO 2006 Growth Nutrients Unit RA SUL RA SUL RA SUL Protein g Arginine g Histidine g Isoleucine g Methionine g Methionine-Cysteine g Leucine g Lysine g Phenylalanine g Phenylalanine-Tyrosine g Threonine g Tryptophan g Valine g Taurine (canned) mg Taurine (dry) mg Crude Fat g Linoleic acid g Alpha Linolenic Acid g Arachidonic Acid g EPA/DHA g Calcium g Phosphorus g Ca/P ratio Magnesium mg Sodium g Potassium g Chloride g Iron mg Copper mg (3.75) 1.25 (3.75) Zinc mg Manganese mg Selenium µg Iodine mg Vitamin A IU Vitamin D IU Vitamin E IU Vitamin K µg Thiamin B1 mg Riboflavin B2 mg Pyridoxine B6 mg Niacin mg Pantothenic Acid mg Cobalamin B12 µg Folic Acid µg Biotin µg Choline mg

29 Appendix 1 Energy requirements for gestation, lactation and growth The following formulae are recommended by the National Research Council (NRC) for daily energy requirements (kcal) during gestation, lactation and growth. Dog gestation owth Growth (puppy & junior) The NRC recommends the following energy equation for late gestation (4 weeks after mating): Energy = 130W ) for daily energy 0.75 Energy = 130W 0.75 Cat gestation (-0.87p) X 3.2[e - 0.1] Where W = actual body weight, Wm = predicted mature adult weight, p = W/Wm + 26W ght, 0.67 Where W = actual body weight Lactation Where W is equal to body weight in kilograms Number of kittens Energy requirement (kcal day - 1) Lactation Cat gestation0.75 <3 100W WL W WL 100W WL Growth (kitten) Energy = 145W + W(24n + 12m)L Energy = 140W Energy = 100W X 6.7[e(-0.189p) 0.66] Where W = body weight, n = number of puppies litter from 1 to 4, Where W = actual body weight, Where W = actual body in weight m = number of puppies from 5 to 8, p = W/Wm, Lactation L = correction figure for stage of lactation, Wm = expected mature body weight varying from 0.75 (week 1) to 1.2 (week 4) Number Energy requirement of kittens requirements (kcal day - 1) Energy for gestation, lactation and growth 1] Energy = 140W Appendix 1 >4 Where W = body weight, L = stage of lactation factor: Weeks 1 & 2 = 0.9 Weeks 3 & 4 = Week 5 = WL <3 100W The following formulae are recommended by the National Research Council (NRC) for daily energy Week 6 = requirements (kcal) gestation, lactation and growth. Week 7 = Wduring + 60WL >4 100W WL Dog gestation Where W = body weight, Growth (puppy & junior) L = stage of lactation factor: The NRC recommends the following energy equation Weeks 1 & 2 = 0.9for late gestation (4 weeks mating): Weeks 3 &after 4 = Energy = 130W 0.75 Cat gestation (-0.87p) X 3.2[e - 0.1] Where W = actual body weight, Wm = predicted mature adult weight, p = W/Wm Week 5 == 130W W Energy Week 6 = 1.0 WALTHAM bookto of healthy weight maintenance for cats and dogs Appendix 1 Week Where7W=pocket is0.8 equal body weight in kilograms Lactation Quit Printer 0.75 Energy = 145W Home + W(24n + 12m)L Contents Where W = body weight, n = number of puppies in litter from 1 to 4, m = number of puppies from 5 to 8, L = correction figure for stage of lactation, varying from 0.75 (week 1) to 1.2 (week 4) Energy = 140W 0.67 Where W = actual body weight Lactation Number of kittens Energy requirement (kcal day - 1) <3 100W WL W WL >4 100W WL Where W = body weight, L = stage of lactation factor: Reference: WALTHAM pocketbook of healthy weight maintenance for cats and dogs - Appendix 1 Back Next Weeks 1 & 2 = 0.9 Weeks 3 & 4 = 1.2 Week 5 = 1.1 Week 6 = 1.0 Week 7 = WALTHAM pocket book of healthy weight maintenance for cats and dogs Appendix 1