Science diet dog food-Nutrition


FREQUENTLY ASKED QUESTIONS


1) What is the best diet? 

There is no one best diet for dogs. Individual dogs, like individual people, digest food differently. Your dog should be fed a diet that is balanced and, if it is a commercial diet, approved by the Association of American Feed Control Officials (AAFCO) for the stage of life your dog is in (e.g., growing, maintenance, performance). I consider easy maintenance of correct body weight, normal feces, normal activity, and normal hair coat as evidence that your dog is on a good diet.


 2) My dog was just bred. When should I change her diet and to what? 

Pregnant dogs do not need a change in diet for the first month after they have been bred. During that first month, the pups are developing but are not growing significantly. In the second month of pregnancy, the bitch needs an increase in calories. She can be fed either more of her regular food or a growth or performance food. I prefer thelatter because many dogs have trouble eating a significant amount of food late in pregnancy, when their uterus is taking up much of the space in their abdomen. When you change diets, if you use diets from the same company and mix the foods, gradually increasing the amount of the higher-calorie food, you will be less likely to cause diarrhea .


3) What about raw-food diets? 

The main concerns about raw-food diets focus on possible spread of bacteria from the ingredients in the diet to the dog and to humans and possible inadequately balanced nutrients. Supporters of raw-food diets claim great improvement in activity and general health of the dog. I personally am not a proponent of raw-food diets but encourage you to speak with your veterinarian and other breeders to help you deccide whether they would be right for your dog.


4) Is goat’s milk a good supplement for puppies? 

If the pup is to be completely hand-raised, canine milk replacers have a much more similar nutrient content to bitch’s milk than do either goat’s milk or cow’s milk. If the pups are nursing off the bitch and you want to give some extra goat’s milk as a supplement, be careful not to give so much as to decrease the pups’ desire to nurse or to cause diarrhea. 



science diet dog food-Nutrition
science diet dog food-Nutrition



BASIC NUTRITION

Nutrition is the study of which compounds are required to be ingested by a given animal and how the animal breaks down and uses those compounds. Nutrients are compounds taken in by animals to provide necessary energy and the building blocks that allow tissue growth and repair. Nutrient requirements vary between species and may vary between individual animals within a species, especially as they progress through different life stages (e.g., growth, pregnancy, old age). Much remains unknown about canine nutrition, and most research is performed by large pet food companies. Most of the research to date has worked to determine minimally acceptable levels of various nutrients, which is not the same as knowing the optimal amounts of given nutrients; it may well be that future research will allow us to refine how we feed dogs so as to maximize the effect of nutrition on health and performance. The information presented here reflects what has been reported in the veterinary literature.


PHYSIOLOGY OF NUTRITION


What happens when an animal eats food? 
The food is broken down by the teeth and by enzymes in the saliva. Further physical breakdown of the food happens as it passes through the muscular activity of the stomach and into theintestinal tract. Other substances added to the food as it passes through the intestinal tract include acids, bicarbonate, bile, and water.
 By the time the digested food leaves the stomach and enters the small intestine, it is the consistency of watery mush. Enzymes are proteins secreted throughout the body that facilitate specific biological processes. In the mouth and intestinal tract, enzymes break down complex nutrients into smaller components that can then be absorbed through the intestinal wall directly into cells or into the bloodstream.
 Many of the nutrients absorbed into the bloodstream pass to the liver, where they are further processed. Any portion of the food that cannot be broken down into a usable nutrient passes into the large intestine, where it is excreted as feces. Some components of nutrients are passed into the urinary bladder and excreted as urine. 
Animals are required to ingest some compounds and can make others in their body. For example, glucose is a simple sugar that is vital to the function of brain cells and most other cells in the body. Animals can ingest sugars in the diet; make glucose by breaking down a more complex sugar or other carbohydrate; make glucose from its building blocks of carbon, hydrogen, and oxygen (a process called gluconeogenesis, which occurs in the liver); or make glucose from a storage product called glycogen (a process called glycogenolysis). 
Vitamin C is an example of a compound that must be ingested by one species (humans) but can be made in the body by other species (dogs). Compounds that must be ingested and cannot be synthesized in the body are called essential nutrients.


NUTRIENTS


1. Water

 Water is the most vital compound taken in by animals. The body is composed primarily of water, and adequate hydration is necessary for normal blood pressure and heart function, kidney function, brain activity, and movement of dissolved compounds throughout the body. During lactation (nursing), water needs increase dramatically to support milk production.

2. Carbohydrates 

 Carbohydrates are a class of compounds made up of carbon, hydrogen, and oxygen (Figure 1-1). This class includes simple sugars and complex fiber. The body runs primarily on carbohydrates and is constantly making carbohydrates for fuel by gluconeogenesis and glycogenolysis. Because the animal’s body is capable of making carbohydrates and because carbohydrates are abundant in all types of food, no specific amount or type of carbohydrate is required in the diet.

3. Fats 

Fats are complex compounds. The basic structure of any lipid or fat is the compound glycerol attached to three fatty acid chains (Figure 1-2). Fats provide a greater number of calories when they are broken down than do any other nutrients and often are used as a primary source of energy in diets. Fats
are necessary for movement in the body of those substances that dissolve in fat, such as the fat-soluble vitamins A, D, E, and K, and for the formation of fatty substances that enhance body processes, such as development of the myelin sheaths that encircle brain cells. 
The amount of fat required in the diet varies with the life stage of the animal. 
Because fats are necessary for the growth and development of body systems and are a concentrated source of energy, the amount of fat in the diet often is increased in growth diets and in diets used during pregnancy and lactation. Fats may be decreased in senior diets, in which a lower caloric density is preferred.
 Fats cannot be restricted entirely because the fats linoleic and alpha-linoleic acid, derived from plants, and arachidonic acid, derived from animal fat, are essential in dogs and because fat increases palatability of diets.



4. Proteins 

Proteins make up most body tissues and enzymes responsible for normal physiologic processes. Proteins are made up of amino acids; the order and arrangement of the amino acids are what give specific protein its properties (Figure 1- 3). Amino acids are made up of carbon, hydrogen, oxygen, and nitrogen and may also contain sulfur, sugar (glycoprotein), or fat (lipoprotein). Some of the 20 amino acids are essential, and some can be synthesized in the body. For dogs, the 10 essential amino acids are arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. 

Proteins are present in both plants and animals, and all the essential amino acids for dogs are present in plants. Therefore, dogs are not required to eat meat to live. 
If, however, the owner of a dog desires that animal to eat plant protein only, the diet must be carefully balanced to ensure that all the essential amino acids are present in the plants provided. In general, animals on a maintenance diet require 13% to 19% protein. 
Growing and pregnant animals require higher levels of protein, perhaps as high as 25%. Increased levels of protein, when balanced in the diet for calories and other nutrients, are not associated with kidney damage in normal, healthy dogs. Increased amounts of dietary protein may spare muscle tissue in older dogs and may be beneficial in maintaining optimal health during weight loss. Diets specific to life stage are discussed later in this chapter.

5. Vitamins 

Vitamins are carbon-based compounds that are required for life but only in very small amounts. Most vitamins bind to minerals and enhance the activity of biological processes in the body, often by altering enzyme function. Vitamins may dissolve in water (water-soluble vitamins: the B vitamin family, vitamin C) or in fat (fat-soluble vitamins: A, D, E, and K). Essential watersoluble vitamins must be ingested daily. Essential fat-soluble vitamins need not be ingested daily because they can be stored in body fat. Vitamin A is a fat-soluble vitamin intimately associated with vision. Vitamin A also contributes to normal bone development, production of spermatozoa.
(spermatogenesis), and fetal development. The parent compound, retinol, is derived from beta-carotene. It is an essential nutrient and is found in fish liver oils, animal liver, egg yolk, carrots, and dark green or yellow vegetables.
 The B vitamins are a diverse group of water-soluble vitamins that includes thiamin, niacin, riboflavin, and folic acid. B vitamins often are associated with neurologic function and the function of enzyme systems in the liver and other organs. These compounds are readily found in whole cereal grains, organ meats, egg yolk, and fish. Vitamin C is a water-soluble vitamin that can be synthesized by dogs and therefore is not an essential nutrient. Anecdotal reports of the use of vitamin C for prevention or treatment of hip dysplasia or arthritis are unsubstantiated.
 Vitamin D is necessary for calcium regulation and can be synthesized by the body with exposure to ultraviolet light. Compounds in the vitamin D family include cholecalciferol and ergocalciferol. Vitamin E is a fat-soluble vitamin that acts as an antioxidant, preventing cellular damage from normal metabolism. Dietary requirement varies with the amount of the mineral selenium present. Vitamin K is necessary for blood clotting. It can be synthesized by bacteria living in the canine gastrointestinal tract and is therefore not an essential nutrient.


Minerals

 All minerals are essential nutrients, but different minerals are required in different amounts. Minerals required in the diet in large amounts are calcium and phosphorus, both of which must be present in balance to prevent either too low levels of calcium (hypocalcemia), associated with abnormal gait, disorientation, and possible seizures, or too high levels of calcium (hypercalcemia), associated with mineralization of tissues.
 Most of the calcium and phosphorus in the animal’s body are stored in the bones and teeth and can be drawn from those sources if the animal becomes deficient. Calcium is required for blood clotting and for neurologic and muscular functions. Phosphorus is an essential component of many enzyme systems. The optimal ratio of calcium to phosphorus in the diet varies from 0.8:1 to 1.5:1. Minerals that are required in only small amounts are called trace minerals (e.g., iron, zinc). These compounds most commonly work with vitamins to effect biological processes. Trace minerals, although essential, are readily present in the diet.

Fiber

 Fiber is not essential but often is added to diets. Fiber helps prevent constipation by drawing water into the large intestine, and it may help regulate blood sugar levels. In general, higher fiber content decreases the digestibility of carbohydrates, fats, and proteins and increases the volume of feces excreted. 
Fiber may be added to weight loss diets to make the animal feel “full” while ingesting fewer calories




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