Animal Nutrition

1
Animal Nutrition
Ch. 43 pp. 957-965, 973-976

• Reasons for Eating
• Energy Budgets
• Eating and Homeostasis - glucose regulation
• Feeding Mechanisms - general overview
• Digestive systems

2
Why Eat?
Food provides chemical energy for cellular work.
Food provides organic raw materials, such as
carbon skeletons, for growth.
Food provides essential nutrients that the animal
can not make for itself.
3
Energy Budgets
energy consumed in food
4
Energy Budgets - Undernourishment
energy consumed in food
5
Energy Budgets - Overnourishment
energy consumed in food
6
Homeostatic regulation of cellular fuel
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Organic Raw Materials
carbon skeletons and amino acids
8
Essential Nutrients
Essential fatty acids
Vitamins
9
Food Resources

• Liquid - rich in dissolved organic molecules
  blood, plant sap, cell contents.
• Micro-particulate - small particles of detritus
  (decaying organic matter), unicellular algae,
  bacteria.
• Macro-particulate - large masses whole bodies
  of large animals and plants or large pieces of
  these.

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Feeding Mechanisms
Feeding on Liquids
Suction feeding

• Saprozoic nutrition

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Microphagy - Feeding on Small Particles
Suspension feeding
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Microphagy - Feeding on Small Particles
Deposit Feeding
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Microphagy - Feeding on Small Particles
Substrate scrapers
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Macrophagy - Feeding on Large Particles
Particles can range from whole, quite large,
organisms to smaller pieces of organisms.
-Wide range of foods. -Often requires complex
behavior patterns involved with prey capture by
predators.
Ingestion of large food masses usually requires
some form of pre-treatment to break the food down
into smaller pieces.
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Macrophagy - Feeding on Large Particles
External secretion of digestive enzymes to
liquefy food
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Macrophagy - Feeding on Large Particles
Use of teeth for pre-treatment
Carnivores Herbivores Omnivores
17
Teeth within one group of animals can be
specialized for different types of food.
Rift Lake cichlids
18
Digestive Systems
Intracellular Digestion
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Digestive Systems - Intracellular Digestion
Sponges rely on intracellular digestion.
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Gastrovascular Cavities
Cnidarians and flatworms have a simple sac-like
digestive cavity, the gastrovascular cavity, with
only one opening.
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Complete Digestive Systems
Most animals have what is called a complete
digestive system with two openings, a mouth and
an anus, at the ends of a long tube.
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Functional Regions of Digestive Tracts
3) Storage
4) Mechanical processing
2) Transport
5) Digestion - enzymatic breakdown of large
molecules into smaller molecules
7) Formation and evacuation of feces.
6) Absorption - nutrient molecules enter body
cells
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Functional Regions of Digestive Tracts
4) Mechanical processing
2) Transport
7) Formation and evacuation of feces.
1) Food uptake
3) Storage
5) Digestion
6) Absorption