The Role of Lipids in Animal Nutrition

Lipids are any one of a group of fats or fatlike substances, characterized by their insolubility in water and solubility in fat solvents such as alcohol, ether, and chloroform. . The term is descriptive rather than a chemical name such as a protein or carbohydrate. It includes true fats (esters of fatty acids and glycerol); lipoids (phospholipids,, cerebrosides, waxes); and sterols (cholesterol, ergosterol). All lipids like carbohydrates contain carbon, hydrogen and oxygen but the proportion of oxygen in lipids is much lower. In addition, phosphorus is found in some of the more complex lipids.

Triglycerides which are also called neutral fats are commonly known as fats when solid or oils when liquid. Triglycerides are made up of two types of building blocks, fatty acids and glycerol, in a ratio of 3:1 of fatty acids to glycerol. Triglycerides are large molecules and ingested fats and oils must be broken down into their building blocks before they can be absorbed. Oils or fats do not mix with water because polar and non polar molecules do not interact. Triglycerides provide the body’s most efficient and compact form of stored energy, and when they are oxidized, they yield large amounts of energy. Triglycerides are found mainly beneath the skin, where they insulate the deeper body tissues from heat loss and protect them from trauma.

Fatty acid chains with only a single covalent bond between carbon atoms are referred to as saturated. Their fatty acid chains are straight and, at room temperature, the molecules  of a saturated fat are packed closely together, forming a solid. Fatty acids that contain one or more double bonds between carbon atoms are said to be unsaturated  (monounsaturated and polyunsaturated). The double bonds cause the fatty acid chains to kink so that they cannot be packed closely enough to solidify. Hence, triglycerides with short fatty acid chains or unsaturated fatty acids are oils (liquid at room temperature) and are typical of plant lipids. Examples include olive and peanut oils (rich in monounsaturated fats) and corn, soybean, and safflower oils, which contain a high percentage of polyunsaturated fatty acids. Longer fatty acid chains and more saturated fatty acids are common in animal fats such as butter fat and the fat of meats, which are solid at room temperature.

Trans fats which are common in many margarines and baked products, are oils that have been solidified by the addition of hydrogen atoms at the sites of double carbon bonds. Trans fats are very harmful to body cells and should be avoided altogether in the animals diet. Trans fats have been linked to atherosclerosis and are considered by many scientists to be carcinogenic.

Phospholipids are modified triglycerides with the addition of a phosphorous-containing group. Phospholipids are the chief material for building cellular membranes.

Steroids are basically flat molecules made of four interlocking hydrocarbon rings. Steroids are very important molecules which the animal gets from ingestion of  animal products such as eggs, meat and cheese. The steroids cholesterol, bile salts, Vitamin D, sex hormones, and adrenocortical hormones are extremely important to the animals health. Cholesterol is the structural basis for manufacture of all body steroids and is a component of the cells membrane. Bile salts are manufactured by the liver from the breakdown of cholesterol and are stored in the gall bladder for release into the small intestine where they aid fat digestion and absorption by helping to emulsify fats into smaller absorbable molecules.Vitamin D is a fat-soluble vitamin produced in the skin on exposure to UV radiation and is necessary for normal bone growth and function. The steroid sex hormones estrogen, progesterone and testosterone are necessary for reproductive function. Adrenocortical hormones like cortisol is a metabolic hormone necessary for maintaining normal blood glucose levels. Aldosterone another adrenocortical hormone helps to regulate salt and water balance in the body by targeting the kidneys.

Other lipid substances include the fat soluble Vitamins A, D, E, and K. Vitamin A is ingested in orange-pigmented vegetables and fruits and are converted in the retina to retinol and are a part of the photoreceptor pigments involved in vision. Vitamin E is ingested in plant products such as wheat germ and green leafy vegetables and protects the cell membrane against oxidative damage. Vitamin K is made by bacterial synthesis in the intestine and is also found in green leafy vegetables and it regulates the formation of clotting factors in the blood.

Eicosanoids (prostaglandins, leukotrienes and thromboxanes) are a group of molecules that are derived from fatty acids found in all cell membranes. Prostaglandins stimulate uterine contractions, regulate blood pressure, control gastrointestinal tract motility and secretory activity. Both prostaglandins and leukotrienes are involved in inflammation. Thromboxanes are powerful vasoconstrictors.

Lipoproteins are lipoid and protein based substances that transport fatty acids and cholesterol in the blood stream. The major lipoproteins are high-density lipoproteins (HDL) and low-density lipoproteins (LDL). HDL is healthy for the body and high levels of LDL is lousy for the body.

Essential Fatty Acids (EFA) are fatty acids that the animal can not synthesize themselves and so it is essential for the animal to get these in its diet. Essential fatty acids in the dog and cat include linolenic acid, linoleic acid and arachidonic acid. Adult dogs are able to synthesize linolenic and arachidonic acid from linoleic acid.  Adult cats, however, can synthesize linolenic acid but not arachidonic acid. Arachidonic acid is only found in fat sources from animals and for this reason cats are obligate carnivores.

Deficiencies in lipids can cause a dry coat and scaly skin. A reduction of lipids on the skin can cause pyoderma. Wound healing can also be impaired due to the requirement of phosopholipids within the cells membranes. If there is a chronic deficiency of lipids, especially of the EFA, symptoms of alopecia, edema and moist dermatitis can occur. Severe deficiencies can result in emaciation of the animal.  Deficiencies of  Vitamin A can cause night blindness, infertility, crusting lesions of the nares, seborrhoeic coat conditions, and increased susceptibility to microbial infections. Deficiencies of Vitamin D can cause rickets in the young and osteomalacia in adults. Deficiencies of Vitamin E can cause pancreatitis, skeletal muscle dystrophy, reproductive failure and impairment of the immune response in dogs. Deficiencies of Vitamin K is rare due to its synthesis in the intestine.

In the next post on animal nutrition we will wrap up the subject of nutrients by covering water soluble vitamins and minerals.

Proteins the Basic Structural and Functional Material of the Body

Proteins are the largest molecules in the body. Some scientists say that the main function of the cell is to produce proteins. Proteins make up 10-30% of the cells mass and can either be functional or structural molecules. Proteins are a class of complex nitrogenous compounds that are synthesized by all living organisms and yield amino acids when hydrolyzed. Proteins in the diet provide the amino acids necessary for the growth and repair of animal tissue.  All amino acids contain carbon, hydrogen, oxygen and nitrogen and some also contain sulfur. About 20 different amino acids make up animal proteins, which may contain minerals such as iron or copper. A Protein consists of from 50 to thousands of amino acids arranged in a very specific sequence. The essential amino acids are those that the liver cannot synthesize (tryptophan, lysine, methionine, valine, leucine, isoleucine, phenylalanine, threonine, arginine and histidine); they are essential in the diet, and a protein containing them is called a complete protein. An incomplete protein lacks one or more of the essential amino acids. The nonessential amino acids are synthesized by the liver. Sources of amino acids in the diet are: Milk, eggs, cheese, meat, fish, and some vegetables such a soybeans are the best sources. Proteins are found in both vegetable and animal sources of food. Many incomplete proteins are found in vegetables; they contain some of the essential amino acids. A vegetarian diet can make up for this by combining vegetable groups that complement each other in their basic amino acid groups. This provides the body with complete proteins. Ingested proteins are the source of amino acids needed to synthesize the body’s own proteins, which are essential for growth of new tissue or the repair of damaged tissue, proteins are part of all cell membranes. Excess proteins in the diet may be changed to simple carbohydrates and oxidized to produce ATP. High levels of exercise, menstruation, pregnancy, lactation and convalescence from severe illness require increased protein intake. Excess protein in the diet results in increase nitrogen excretion in the urine. Amino acids are strung together through dehydration synthesis to form a complete protein. There are two classes of proteins in the body; fibrous and globular. In the next blog post we will look at the varied functions of both classes of proteins. Since dogs and cats are primarily carnivores it is important to know how proteins work in the body and what their daily requirements for proteins are. Once we are finished with discussing the basic nutritional elements we can begin to look at the sources of quality nutrients and how these nutrients enter into the body for use by the cells.

Enzymes and Catalysts, Essential for Animal Health

Enzymes are chemically specific in the body and as we have seen in the last blog are made up of a protein part and a cofactor or coenzyme. Enzymes are named for the type of reaction they catalyze. Hydrolases add water during the hydrolytic reactions and oxidases add oxygen. When we see the suffix -ase at the end of a term we know it is an enzyme. Some enzymes that were found before the common use of the suffix will not have an -ase at the end of the term like pepsinogen, pepsin and trypsin. Enzymes are manufactured by the cells in an active or inactive form. The inactive forms need to be triggered to become active by the presence of a specific molecule. There are six classes of enzymes; hydrolases, isomerases, lipases, lyases, oxireductases and transferases. Each class of enzyme has its own function in either breaking down or building up substances in the body. For instance lipase breaks down fat lipid molecules, proteases break down proteins into amino acids, fructase breaks down fructose, galactase breaks down galactose, amylase breaks down simple sugars, and the list could go on and on. Digestive enzymes break down the food the animal eats in the process of chemical digestion into smaller molecules that can be absorbed into the intestinal cells for transportation across and out of the cell and into the blood and lymph vessels. Enzymes are critical to all of the cells internal functions as well. Enzymes in the cell trigger a variety of metabolic processes that are vital to cell functions. Sources of enzymes in the animals diet are from fresh fruits and vegetables, fermented foods like yogurt, kefir and buttermilk or organ meats like the pancreas and liver organs of the animals they eat if they are meat eaters. In order for enzymes to work correctly they need to maintain their shape so substrates can bind to them and the anabolic or catabolic activity can take place. In anabolic processes substances are built up by the removal of a water molecule and in catabolic processes water is used to split apart the substrate. The oxireductase enzymes use oxygen in this process instead of water. Enzymes change their shape and become unusable under certain conditions. When body temperatures rise above 104 degrees or when the acid-base balance is disturbed enzymes lose their shape and become incapable of functioning correctly. Biological enzymes need to live in an environment that remains in homeostatic balance. Live unprocessed foods are the best sources of biologically active enzymes. Any time you cook a vegetable, fruit or organ meat you would be destroying the enzymes by altering their shape. Processed foods are have the least biologically available enzymes and raw or fermented foods have the most biologically available enzymes. Certain cells in the body manufacture enzymes from the raw amino acid, vitamin and mineral resources that enter into the body through the diet. If the animal does not get the correct kind and amount of amino acids, vitamins and minerals in their diet the bodies cells will not be able to manufacture the enzymes that are needed in the cellular processes. Many of the digestive problems that animals have today are a direct result of food processing processes that apply heat and radiation to manufacture what I call animal junk food. If the animal is having digestive and elimination problems that is not caused by a parasite, genetic disease, or an allergen you can be certain that there is a lack of enzyme production in the cells due to poor nutrition. In subsequent blogs we will look at how to remedy this problem once we have covered the basics of nutritional elements.

Carbohydrates-The Fuel Source

Carbohydrates or watered carbons are the fuel source that provides the body with ATP ( Adenosine Triphosphate). Every cell in the body uses ATP to provide power for the bodies metabolic activities. In the cell the mitochondrion breaks down glucose molecules and transforms the energy that is stored in glucose into ATP. The energy that is stored in the high energy phosphate bonds is then transfered to the organelles within the cell that do the work of the cell. What is left after the transfer of energy from the phosphate bond is a molecule of ADP or ( Adenosine Diphosphate) which can be broken down further and the remaining high energy phosphate bond can be used by the cells as a energy source. What is left is AMP or ( Adenosine Monophosphate) . Carbohydrates are classified according to size; monosaccharides, disaccharides and polysaccharides. Two monosaccharides joined together through dehydration synthesis is called a disaccharide and many monosaccharides joined together through dehydration synthesis is a polysaccharide. Monosaccharides are either hexose or pentose sugars meaning that they either have a six carbon or five carbon structure respectively. The monosaccharides; glucose, fructose, and galactose are hexose monosaccharides and deoxyribose and ribose are the common pentose sugars used by the body. Ribose and deoxyribose are important sugars found in our DNA. Sucrose, maltose and lactose are the primary disaccharides that the body uses. Sucrose is made up of the monosaccharides glucose and fructose joined together, maltose is made up of two glucose molecules joined together and lactose is made up of galactose and glucose joined together. The polysaccharide glycogen is made up of many monosaccharides joined together and is the primary energy storage carbohydrate. When the animal gets more carbohydrates then it uses in its diet these carbohydrates are joined together in the liver and transported through the blood for storage between muscle cells or remain in the liver where they will be broken back down into glucose when blood sugar levels drop. The disaccharide molecules that the animal consumes in its diet come from plant sugars like beet sugar, cane sugar, fruit sugars and milk sugars. The disaccharides are to large to pass through the cells of the lining of the intestine and must be broken down through hydrolysis with the assistance of an enzyme into simple sugars (monosaccharides). Polysaccharides that are polymers of simple sugars that the plant produces by dehydration synthesis are starches that the plant uses as a storage molecule and these large sugar molecules must also be broken down by hydrolysis with the aid of enzymes into simple sugars that can cross the intestinal cells membranes. Starches in the animals diet come from potatoes and grains that contain large amounts of starches. What is hydrolysis and dehydration synthesis? Hydro- means water and -lysis means to split apart or break down. Synthesis means to build up or combine together. So hydrolysis is to spit apart compounds or molecules by adding a water molecule and dehydration synthesis which is the opposite of this process is to join two molecules together by removing a water molecule. Both of these processes use an enzyme to assist in this process. Enzymes are globular proteins that act as catalysts. Catalysts are substances that regulate and accelerate the rate of biochemical reactions but are not used up or changed by these reactions. Each enzyme is made up of a protein part and a cofactor that can be a metal element or an organic molecule like a B complex vitamin. Each enzyme in the body is specifically formed to work with only one substrate ( the substance that any enzyme interacts with). In the next blog we will look at the important roles of enzymes in the body and the sources of carbohydrates commonly found in the animals diet.

Strategies For Increasing Water Intake In Cats And Dogs

In the last blog we talked about the importance of water in the animals diet and what the qualities of water are. There are many conflicting statements about how much water and animal should get. The same holds true with human water consumption requirements. Some experts talk about requirements based on animal weight and a certain amount of water with a specific pound of body weight to ounce of water ratio. The animal generally knows when they need water and all that the caretaker needs to do is supply an easy to access water supply from a clean untreated water source. There is a plethora of water bowls and automatic feed water units on the market. The one thing to remember with water bowls is to clean them thoroughly every we fill the water bowl especially if several animals share the same water bowl. If your animal companion has a plentiful supply of fresh water available to them and they are still dehydrated then we can encourage them to drink more water by adding a flavoring agent to the water that tastes good to that particular animal. Organic, free range beef bullion cubes can be found in the health food store and we can add this to a separate water bowl beside the fresh water bowl and see if this will encourage the animal to drink more water. Fish emulsion or bonita flakes can be added to a cats water bowl to see if the cat will drink more water. We should make sure that at all times a separate bowl of fresh water is available. We can also prepare a vegetable or meat stock and put it in a separate bowl for the animal to consume. Find a flavor that your dog or cat likes and they will most likely drink more water. The signs of dehydration in animals are, scanty and dark urine, constipation, straining while defecating, dry skin, dry nose, dry foot pads, over breathing to cool down the body, loss of skin elasticity, lethargy, depression, sunken eyes, dry gums and a general lack of energy. We need to remember that with dehydration there generally is a shortage of electrolytes in the fluids of the body. If the animal is dehydrated we can add a little pinch of natural sea salt to the water to build the electrolyte balance back up. If the animal gets severely dehydrated hyperthermia will set in and this can lead to shock. Dehydration is can be a dangerous condition for an animal. Anyone living in a hot climate will need to monitor there companions water intake during the dry hot months. I see a lot of people out on the hiking trails where I live with their dogs and they often fail to bring a water bottle for the dog. Just as we need water while we are sweating and using our body so do animals.

Water, The Universal Solvent

Water is essential for life. Approximately two thirds of the body is water and two thirds of the earth is covered by water. H2O is a polar molecule that has many important biological characteristics. Water has high heat capacity, it absorbs and releases large amounts of heat before changing temperature itself. As part of blood, water redistributes heat among body tissues, ensuring temperature homeostasis. Water has high heat of vaporization. When water evaporates, it changes from liquid to gas. Water in perspiration helps cool the body. Water has polar solvent properties. Because water molecules are polar, they orient themselves with their slightly negative ends toward the positive ends of the solutes in a water solution and surround them. The polarity of water helps ionic compounds, acids and bases dissociate in solution and become evenly scattered in the solution. Water is the body’s major transport medium. Nutrients, respiratory gases, and metabolic wastes carried throughout the body are dissolved in blood plasma, and many metabolic wastes are excreted from the body in urine. Mucus is another fluid lubricant in the body that is made up of water. Water is a reactant in many chemical reactions in the body. Hydrolysis reactions add water to the decomposition reactions in the body to break the chemical bonds of the nutrients that are eaten to break them down into smaller molecules that can be carried across the intestinal wall for example. Conversely, when large carbohydrate or protein molecules are synthesized from smaller molecules, a water molecule is removed for every bond that is formed. Water is a cushion that helps protect from physical trauma. The cerebrospinal fluid that bathes the brain is an example of waters cushioning ability. Without the correct amount of water in the system the animal will become dehydrated and body temperature will rise to cell damaging temperature levels, proteins will start to unravel and enzymes will not work when their shape is changed by the excess heat. In the next blog we will talk about the different pathological conditions that are caused by dehydration and how to make sure your animal companion gets a sufficient amount of quality water into their system.

Companion Animal Nutrition Overview

By Nickie Scott

The beginning blogs on this subject will slowly lay a foundation of general scientific knowledge about the physiology, anatomy, pathology and nutritional requirements for animal health so that caretakers can make knowledgeable decisions about maintaining the health of their companion animals. There is a lot of conflicting information on the internet about the health requirement needs of companion animals and many people are looking for specific information that relates to some already existent pathological condition that their animal companion is experiencing. Without a basic understanding of what the animals requirements for maintaining homeostasis are we will not be able to make informed decisions on how to best promote general health and balance for the animals under our stewardship. Our first subject will be nutrition for companion animals. Let’s face it. The reason that animals form a bond with humans is not based on petting alone. Easy access to food and safe shelter are the main reasons that animals form this cross species bond. The first known domestication of animals happened around 13,000 BC and started with the dog (canis lupus familiaris) in east asia. Some 4,500 years later the domestication of cats (felis silvestris lybica) started in the fertile crescent around 8,000 BC. It wasn’t until 3,600 BC that the horse (equs caballus) started to be domesticated in what is now known as Kazakhstan. Domesticated dogs helped humans protect themselves from predators and helped to herd food animal herds. Until the dawn of processed animal food in 1860 by James Spratt of London, England domesticated dogs mainly lived off of table scraps or remnants of the hunt. Cats generally would eat the rodents that feed off of the grain humans stored  but were also feed table scraps. Horses grazed the areas of their confinement and were supplemented with dried grasses when possible. While dogs and cats were enticed by the easy access to food and comfortable shelter, horses were basically enslaved for the benefit of humans. Maybe this is why their domestication started at a much later date then dogs and cats. It is much easier to entice a dog with food then a cat and even harder to entice a horse with food unless they are starving and conditioned to accepting food from humans.

Now that we know a little of the history of our intercession with domesticated animals we can start with the basic science of nutrition. Nutrition is defined as the process of providing or obtaining the food necessary for health and growth. Nutrients are defined as, a substance that provides nourishment essential for the growth and maintenance of life. Nutrients provide the energy that all living beings need to produce the work of the cells and provide the building blocks that the body needs to maintain its structure. The source of all nutrients that the body needs come from one place, the earth. The energy that the nutrients contain to do work comes from one place, the sun. Since we can not eat the sun to get energy to do work we must have an intermediary to gather and store this energy in a form that can be transformed into an energy source that we can use as living animals and that intermediary is plants. Plants gather the energy of the sun and utilize it for their own growth and function and store the remainder as chlorophyll and oils. Plants gather elements of the earth up through their roots along with water and produce oxygen that other living beings need to spark the metabolic processes of the body. Livings beings then consume the plant material and break down the plant into an assimilable size so that we can use the energy and building blocks that were provided by the sun and earth or they eat the animal that has eaten the plant.  Each living being has specific nutritional needs based upon the structural, environmental and work requirement of that particular life form. Since we are looking at only three specific animals we will need to know what the requirements are for each of these animals. Each type of animal is unique and has its own nutritional requirement as a species. Within each species there are also specific nutritional requirements based on size, genetics, environment, age, work habits and pathological imbalances. Each animal is a bio-individual so when we look at the nutritional requirements for the animal we must take all of these factors under consideration if we are to make wise choices in what we feed to our animal companions. Currently most of the information we have about animal nutrition for dogs, cats and horses are provided by the AAFCO. The Association of American Feed Control Officials Inc. reports it’s scientific findings to the FDA which then regulates pet food only when necessary to protect the general public, environment or poses a risk to the health of the animal. The AAFCO is a corporation not a government agency but it sets minimum requirements for pet food. It’s members are not required to follow these guidelines. We also get information from university studies on companion animal nutrient requirements but those studies are funded by the pet food industry or government grants. We would generally need to look at veterinary college studies to get information that is not subverted by the requirements of a desired outcome by the entity that is funding the study. Just as we see dietary fads in human nutrition we also see dietary fads in what people feed their animal companions. Each of these dietary fads probably contains some truth as well as some myth or incomplete information. Were are we to turn to find the knowledge we need to make intelligent choices on what to feed our companions? I think that the first place to start is learn more about what the bodies requirements are is to learn more about what nutrients are, where they come from and how they function in the body. In our next blog we will begin to lay the ground work of nutritional elements and where they come from. Once we know the basic chemical composition of nutrients we can look at how these nutrients enter into the body and get delivered to the cells. We will then look at bio-individual needs that are based on breed, environment, work levels, and pathological conditions. Once we know these basic subjects in nutrition we will look at the nutrients that are available to us, their manufacturing processes, quality and economics of nutrition. By the end of this subject we should have a clearer picture of how we can promote health through correct feeding that stays within the budget that we have available to us to feed our companions.

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