CHAPTER 20. Nutrition
Patricia A. Schenck
NUTRIENTS
I. Water
A. Water is the most important nutrient
B. Requirement (mL/day) roughly equals 1.6 * resting energy requirement (RER) in dogs and 1.2 * RER in cats
II. Carbohydrates
A. Includes sugars and starches
B. Utilized as a source of glucose
C. Carbohydrate ingredients include grains (e.g., wheat, corn, rice, barley, oats)
D. Cooking increases the digestibility of carbohydrates
III. Fiber
A. Resists enzymatic digestion; is fermented in the colon
B. Fiber promotes and regulates normal bowel function
C. Fiber sources differ in their fermentation properties
D. The amount of fiber in the diet impacts the digestibility of the food
IV. Protein
A. Proteins are composed of amino acids. Ten amino acids are essential in a dog diet, and 11 are essential in the cat
B. Catabolism of protein produces waste nitrogen and generates ammonia, which can be toxic
C. Protein is required in the diet because amino acids are continually being used in metabolic pathways
D. Most commercial diets contain excess protein
V. Lipids
A. Certain fatty acids (linoleic acid in the dog, linoleic and arachidonic acid in the cat) are required in the diet
B. Fats are an important source of energy, providing more than twice the energy per gram compared with protein or carbohydrate
C. Dietary fat improves the absorption of the fat soluble vitamins (A, D, E, and K)
VI. Minerals
A. Required for many important functions in the body
B. Minerals from meat sources are typically better utilized than minerals from plant sources
C. A variety of medical problems can result from deficiency or excess of minerals
1. Calcium
a. Deficiency: Decreased bone mineralization, bone fractures
b. Excess: Nephrosis, enlarged costochondral junctions
2. Phosphorus
a. Deficiency: Pica, rickets, poor growth
b. Excess: Bone loss, calcification of soft tissues
3. Potassium
a. Deficiency: Anorexia, heart and kidney lesions
b. Excess is rare
4. Sodium, chloride
a. Deficiency: Inability to maintain water balance
b. Excess: Thirst, seizures, death
5. Magnesium
a. Deficiency: Muscular weakness, irritability, decreased bone density, seizures
b. Excess: Uroliths, paralysis
6. Iron
a. Deficiency: Anemia, poor coat
b. Excess: Anorexia, decreased liver function
7. Zinc
a. Deficiency: Alopecia, depigmentation of hair
b. Excess: Rare
8. Copper
a. Deficiency: Depigmentation of hair, neuromuscular disorders
b. Excess: Increased activity of liver enzymes
9. Manganese
a. Deficiency: Crooked legs, fatty liver
b. Excess: Rare
10. Iron
a. Deficiency: Goiter, reproductive failure, myxedema
b. Excess: Goiter, decreased appetite
11. Selenium
a. Deficiency: Muscular dystrophy, subcutaneous edema, renal mineralization
b. Excess: Vomiting, staggering, salivation, nail loss
12. Chromium
a. Deficiency: Impaired glucose tolerance
b. Excess: Dermatitis, lung cancer
VII. Vitamins
A. Vitamins A, D, E, and K are fat-soluble vitamins. Intestinal absorption requires bile salts and micelle formation; absorption is by passive transport. They are stored in fat; thus deficiency is less likely; however, they are more likely to cause toxicity
B. The remaining vitamins are water soluble and are absorbed by active transport. They can be depleted, rapidly causing deficiency; toxicity is uncommon
C. A variety of medical problems can result from deficiency or excess of minerals
1. Vitamin A
a. Deficiency: Anorexia, poor growth, weakness, fetal resorption
b. Excess: Tooth loss, poor growth, cervical spondylosis
2. Vitamin D
a. Deficiency: Rickets, osteomalacia, bone fractures, enlarged costochondral junctions
b. Excess: Hypercalcemia, calcinosis, anorexia, lameness
3. Vitamin E
a. Deficiency: Steatitis, dermatitis, anorexia, myopathy, immunodeficiency, sterility
b. Excess: Minimal toxicity, impairment of absorption of other fat soluble vitamins, prolonged clotting times
4. Vitamin K
a. Deficiency: Prolonged clotting time, hemorrhage
b. Excess: Minimal toxicity, anemia
5. Thiamin (vitamin B 1)
a. Deficiency: Anorexia, weight loss, ventriflexion in cats, paresis in dogs
b. Excess: Hypotension, bradycardia
6. Riboflavin (vitamin B 2)
a. Deficiency: Ataxia, retarded growth, dermatitis, ocular discharge, bradycardia, fatty liver in cats
b. Excess: Minimal toxicity
7. Niacin (vitamin B 3)
a. Deficiency: Anorexia, diarrhea, poor growth, ulceration of mucosa and necrosis of tongue, drooling
b. Excess: Melena, convulsions
8. Pyridoxine (vitamin B 6)
a. Deficiency: Anorexia, weight loss, poor growth, microcytic hypochromic anemia
b. Excess: Anorexia, ataxia
9. Pantothenic acid
a. Deficiency: Fatty liver, emaciation, poor growth, tachycardia, coma
b. Excess: No toxicity
10. Folic acid
a. Deficiency: Anorexia, weight loss, glossitis, leucopenia, megaloblastic anemia in cats, hypochromic anemia
b. Excess: No toxicity
11. Biotin
a. Deficiency: Hyperkeratosis; alopecia; crusty secretions around eyes, nose, and mouth; drooling; diarrhea
b. Excess: No toxicity
12. Cobalamin (vitamin B 12)
a. Deficiency: Poor growth, anemia
b. Excess: Altered reflexes
13. Vitamin C: No signs of deficiency or toxicity in dogs or cats
14. Choline
a. Deficiency: Thymic atrophy, poor growth, anorexia, fatty liver
b. Excess: No toxicity
15. Carnitine
a. Deficiency: Cardiomyopathy, hyperlipidemia
b. Excess: No toxicity
ENERGY REQUIREMENTS
I. Dogs
A. Resting energy requirement (RER)
1. RER (kcal) = 70*(body weight [BW] [kg]) 0.75
2. If BW is between 2 and 45 kg, RER (kcal) is approx 30*(BW [kg]) + 70
B. Maintenance energy requirement (MER) depends on physiologic state and ranges from 1.0 * RER in obese individuals to 1.8 * RER in intact adults
C. Work energy requirement ranges from 2 * RER for light work to 8 * RER for heavy work
D. Gestation
1. First 42 days, feed as an intact adult (1.8 * RER)
2. Last 21 days, feed 3* RER (or more if needed)
E. Lactation energy requirement ranges from 4 to 8 * RER, depending on the number of puppies nursing
F. Growth energy requirement
1. First 4 months of life= about 3 * RER
2. After 4 months = about 2 * RER until adult size is reached
II. Cats
A. RER is calculated as for dogs
B. MER ranges from 0.8 * RER in obese individuals to 1.6 * RER in active intact adults
C. Gestation
1. Energy requirements increase linearly during gestation
2. Feed at 1.6 * RER at breeding and gradually increase to 2 * RER by parturition
3. Free-choice feeding is recommended
D. Lactation energy requirement ranges from 2 to 6 * RER, depending on the number of kittens nursing
E. Growth energy requirement is about 2.5 * RER until adult size is reached
PET FOODS
I. Federal and state agencies regulate pet food labels and ingredients. The Association of American Feed Control Officials (AAFCO) has regulations regarding the ingredients that can be included in commercial pet foods. They also regulate what may be stated on the pet food label
II. Pet food labels
A. The display panel must include the manufacturer’s name, the name of the product, net weight, which stage of life the food is designed for, a description of the product, and the nutrition claim
1. Ingredients must be listed in descending order by weight in the formula. Ingredient names must conform to AAFCO guidelines. The ingredient list gives information regarding relative amounts, but it does not provide any information as to the quality or digestibility of the ingredients. Also realize that wet ingredients will be at the beginning of the ingredient listing because water in the wet ingredient contributes to the weight, making it heavier
2. The guaranteed analysis panel must include the minimum percentages for protein and fat and maximum percentages for crude fiber and moisture. These percentages are the percentages “as-fed.” They do not give any indication as to the caloric density or digestibility of the product
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