Nutrition and Disease Management for Veterinary Technicians and Nurses

Ann Wortinger, Kara M. Burns

• Publisher: Wiley-Blackwell
• Year: 2015
• ISBN:
  9781118810866
• Edition: 2
• Topic: Medizin
• Subtopic: Veterinärmedizin

Nutrition and Disease Management for Veterinary Technicians and Nurses, Second Edition offers a thorough update and significant expansion of this easy-to-use introduction to veterinary nutrition and diet, with broader species coverage, a new section on nutritional management of disease, and many new chapters. •Provides a complete reference to veterinary nutrition, from the fundamentals to feeding companion animals of any age and health status
•Adds information on nutrition in birds, small mammals, and horses to the existing dog and cat coverage
•
•Presents a new section on managing disease through nutrition, with 10 new disease chapters
•Offers additional new chapters on nutritional calculations, types of pet foods, raw food diets, additives and preservatives, nutrition myths, nutritional support, and assisted feeding
•Includes access to a companion website with case studies, review questions and answers, and the figures from the book in PowerPoint

SECTION 1

Basics of Nutrition

Chapter 1
Nutrients and Energy

Introduction

Animals, unlike plants, are unable to generate their own energy, and require a balanced diet to grow normally, maintain health once they are mature, reproduce, and perform physical work.^{1, 2} Plants are able to convert solar energy from the sun into carbohydrates thorough a process called photosynthesis, but they too require water, vitamins and minerals for optimal growth and production. Animals in turn either eat plants or eat other animals that eat plants to obtain their energy.^{1, 2}

Nutrients

For animals, energy is provided in the diet through nutrients. Nutrients are components of the diet that have specific functions within the body and contribute to growth, tissue maintenance and optimal health.^{1, 2} Essential nutrients are those components that cannot be synthesized by the body at a rate adequate to meet the body's needs, so they must be included in the diet. These nutrients are used as structural components as with bone and muscle, enhancing or being involved in metabolism, transporting substances such as oxygen and electrolytes, maintaining normal body temperature and supplying energy.^{1, 2} Nonessential nutrients can be synthesized by the body and can be obtained either through production by the body or through the diet.^{1, 2} Nutrients are further divided into six major categories; water, carbohydrates, proteins, fats, vitamins and minerals.

Energy is not one of the major nutrients, but after water it is the most critical component of the diet with energy needs always being the first requirement to be met in an animal's diet.^{1, 2} After energy needs have been met, nutrients become available for other metabolic functions.^{1, 2} Approximately 50–80% of the dry matter of a dog's or cat's diet is used for energy.^{1, 2} The body obtains energy from nutrients by oxidation of the chemical bonds found in proteins, carbohydrates and fats.²

Oxidation is the process of a substance combining with oxygen resulting in the loss of electrons.³ This oxidation occurs during digestion, absorption and transport of nutrients into the body's cells.² The most important energy-containing compound produced during this oxidative process is adenosine triphosphate (ATP), a common high-energy compound composed of a purine (adenosine), a sugar (ribose) and three phosphate groups.^{2, 3}

The biochemical reactions that occur within the body either use or release energy. Anabolic reactions require energy for completion, and catabolic reactions release energy upon completion.² ATP and other energy-trapping compounds pick up part of the energy released from one process and transfer it to the other processes.² This energy is used for pumping ions, molecular synthesis and to activate contractile proteins, these three processes essentially describe the total use of energy by the animal.² Without the energy supplied through the diet, these reactions would not occur and death would follow.²

ATP is the usable form of energy for the body, but not a good form of energy storage because it is used quickly after being produced.² Glycogen and triglycerides are longer-term storage forms of energy.² In fasting animals, when the body needs energy it uses stored glycogen first, stored fat second and finally as last resort amino acids from body protein.² The fatty acids found in triglycerides are not able to be converted into glucose; only the glycerol backbone can be utilized for this purpose. For proteins, they must undergo a process called gluconeogenesis to be converted into usable glucose, and not all proteins are able to undergo this process.⁴

Measures of Energy

Energy represents the capacity to do work. This is measured most commonly in the United States as a calorie. A calorie is the amount of heat that is required to increase the temperature of 1 kilogram of water from 14.5 °C to 15.5 °C (or 1 °C).⁴ As this unit of measure is very small indeed, we commonly use the term kilocalorie (1000 calories). When we look at food labels, this is the unit that is being referenced, a kilocalorie, or kcal.

Although kcal is what is used in the United States, a joule is the SI unit measure of energy. 1 kcal = 4.184 joules. As with calories, a joule is a small unit of measure, and kilojoule (1,000,000 J) and megajoule (1000 J) are the units most commonly used in animal nutrition.⁴

Gross Energy

The total amount of potential energy contained within a diet is called gross energy (GE). GE in food is determined by burning the food in a bomb calorimeter and measuring the total amount of heat produced. Unfortunately, animals are not able to use 100% of the energy contained in a food; some of it is lost during digestion and assimilation of nutrients as well as in urine, feces, respiration and production of heat.^{1, 2}

Digestible Energy

Digestible energy (DE) refers to the energy available for absorption across the intestinal mucosa; the energy lost is that found in the feces. Metabolizable energy (ME) is the amount of energy actually available to the tissue for use; the energy lost is that found in the feces and urine. ME is the value most often used to express the energy content in pet foods.^{1, 2}

When GE values are readjusted for digestibility and urinary losses, ME values of 3.5 kilocalories/g are assigned to proteins and carbohydrates and 8.5 kilocalories/g to fats; these values are called Modified Atwater factors.^{1, 2} These were developed by AAFCO to produce an equation that would more accurately reflect the digestibility of commercial pet foods, which tend to have lower digestibility than typical human foods.⁴

The ME of a diet or food ingredient depends on both the nutrient composition of the food and the animal consuming it.^{1, 2} If a dog and horse are fed the same high-fiber diet, the horse will have a higher ME value due to its bette...