Chapter 41 - Chapter 41 - Animal Nutrition Chapter 41...

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Chapter 41 - Animal Nutrition Chapter 41 Animal Nutrition Lecture Outline Overview: The Need to Feed All animals eat other organisms—dead or alive, whole or by the piece (including parasites). In general, animals fit into one of three dietary categories. 1. Herbivores, such as gorillas, cows, hares, and many snails, eat mainly autotrophs (plants and algae). 2. Carnivores, such as sharks, hawks, spiders, and snakes, eat other animals. 3. Omnivores, such as cockroaches, bears, raccoons, and humans, consume animal and plant or algal matter. 4. Humans evolved as hunters, scavengers, and gatherers. While the terms herbivore, carnivore, and omnivore represent the kinds of food that an animal usually eats, most animals are opportunistic, eating foods that are outside their main dietary category when these foods are available. 1. For example, cattle and deer, which are herbivores, may occasionally eat small animals or bird eggs. 2. Most carnivores obtain some nutrients from plant materials that remain in the digestive tract of the prey that they eat. 3. All animals consume bacteria along with other types of food. For any animal, a nutritionally adequate diet must satisfy three nutritional needs: 1. A balanced diet must provide fuel for cellular work. 2. It must supply the organic raw materials needed to construct organic molecules. 3. Essential nutrients that the animal cannot make from raw materials must be provided in its food. Concept 41.1 Homeostatic mechanisms manage an animal’s energy budget The flow of food energy into and out of an animal can be viewed as a “budget,” with the production of ATP accounting for the largest fraction by far of the energy budget of most animals. o ATP powers basal or resting metabolism, as well as activity and, in endothermic animals, thermoregulation. Nearly all ATP generation is based on the oxidation of organic fuel molecules— carbohydrates, proteins, and fats—in cellular respiration. o The monomers of any of these substances can be used as fuel. o Fats are especially rich in energy, liberating about twice the energy liberated from an equal amount of carbohydrate or protein during oxidation.
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When an animal takes in more calories than it needs to produce ATP, the excess can be used for biosynthesis. o This biosynthesis can be used to grow in size or for reproduction, or it can be stored in energy depots. o In humans, the liver and muscle cells store energy as glycogen, a polymer made up of many glucose units. Glucose is a major fuel molecule for cells, and its metabolism, regulated by hormone action, is an important aspect of homeostasis. If glycogen stores are full and caloric intake still exceeds caloric expenditure, the excess is usually stored as fat. When fewer calories are taken in than are expended—perhaps because of
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This note was uploaded on 08/23/2011 for the course BIO 101 taught by Professor Taylor during the Spring '11 term at University of West Georgia.

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Chapter 41 - Chapter 41 - Animal Nutrition Chapter 41...

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