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Lecture 13
Animal Nutrition
Organisms can be divided into two classes on the basis of their method of nutrition Autotrophic Organisms
Heterotrophic Organisms • bacteria, fungi, protozoa and animals • incapable of manufacturing organic compounds from inorganic nutrients
Nutritional Requirements • nutrient: substance an
organism needs to remain alive • food: any material that contains nutrients
Heterotrophic Organisms
Animal Nutrition Animals: • diverse feeding strategies • are under intense pressure (natural selection) to use food efficiently
Nutrients are molecules that serve as: • sources of metabolic energy • raw material for growth and tissue repair • maintenance of body function • reproduction
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Meeting Basic Needs • • • • • •
Nutrient Requirements
carbohydrates proteins lipids vitamins essential elements electrolytes
Nutrient Requirements
• Carbohydrates, fats, and proteins supply animals with metabolic energy
Understanding Nutrition
calorie: measure of the energy content of food
Calorie: unit of energy
calorie: is the amount of heat needed to raise the temperature of 1 g of water 1°C
• if a single helping of food contains 150 Calories, then 150 kilocalories (kcal) of energy is released when the food is completely oxidized by cells
kilocalorie = Calorie (Cal)
figure 50-02.jpg
Nutrients Provide Energy
Nutrient Requirements
50.2
• Carbohydrates are stored in liver and muscle cells as glycogen
Figure 50.2
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Energy and Exercise • During exercise, glycogen is broken down into glucose • muscle cells use glucose that is released to manufacture ATP • glucose from liver enters bloodstream and is delivered to cells
Nutrient Requirements • the most important form of stored energy in animals is fat • fat has more energy per gram than glycogen
Nutrient Requirements • Glycogen reserves are built up, and then additional carbohydrates, proteins, and fats are converted to body fat • Some species use seasonal over-nourishment to survive periods of food unavailability
Undernourishment • an animal with insufficient caloric intake • must metabolize its stored glycogen, fat and protein
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figure 50-03.jpg
50.3
Figure 50.3 The Course of Starvation
a starving animal must use its own proteins for fuel; Kwashiorkor syndrome
Figure 50.3
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Nutrient Requirements • all animals require certain basic organic molecules that they cannot synthesize
50.4
Figure 50.4
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Essential Amino Acids • humans require 8 essential amino acids • all are available in milk, eggs, meat, but not in all vegetables
50.5
Figure 50.5
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Nutrient Requirements
Essential Fatty Acids Humans are able to synthesize almost all of their required lipids, using acetyl groups from food Essential fatty acids such as linoleic acid must be obtained through a dietary source
• Different animals need mineral elements in different amounts • Macronutrients: needed in large amounts • Micronutrients: needed in small amounts
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50.1
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50.1
Table 50.1 – Part 1
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Vitamins • group of essential nutrients • carbon compounds required for normal growth and metabolism • required in small amounts
50.2
Table 50.2 – Part 1
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table 50-02b.jpg
Malnutrition • results when any essential nutrient is lacking from the diet • chronic malnutrition leads to a characteristic deficiency disease • pernicious anemia (the failure of red blood cells to mature), is caused by B12 deficiency
50.2
Adaptations for Feeding • Heterotrophic organisms can be classified by how they acquire their nutrition
Heterotrophic Organisms: Predators animals that feed on living organisms
• herbivores - eat plants • carnivores - eat animals • omnivores - eat plants and animals
Heterotrophic Organisms: Saprobes
Other Adaptations for Feeding
Bacteria and Fungi
• saprophytic – absorb nutrients from dead organic matter
Detritivores, (earthworms and crabs) Filter feeders, (clams and blue whales) Fluid feeders obtain food from the fluids
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Adaptations for Feeding • because the energy content of vegetation is low, herbivores must process large amounts • teeth of herbivorous vertebrates: evolved to process coarse plant matter
Adaptations for Feeding • behavioral and anatomical adaptations reflect feeding types • teeth have evolved to match diet
Natural Selection • has tightly matched the structure of animal mouthparts to their function in obtaining food
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