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Animal Nutrition
Nutritional requirements
Food types and feeding mechanisms
Overview of food processing
Mammalian digestive system
Nutritional Requirements
• Fuel
• Raw organic materials for biosynthesis
• Essential nutrients which must be obtained in a prefabricated form: vitamins, minerals
• Deficiencies include: kwashiokor-protein deficiency, starvation-insufficient calories,
Overview of Food Processing
• Four stages: ingestion, digestion, absorption, and elimination
• Ingestion-the act of eating• Digestion-process of breaking down food
into small molecules• Absorption-uptake of small molecules • Elimination-undigested material passes out
of the digestive compartment
The Mammalian Digestive System
• Oral cavity-mechanical digestion, chemical digestion of starches
• Esophagus-conducts food to stomach, peristalsis• Stomach-food storage, churning, chemical
digestion, secretion (regulated by gastrin, lining protected
• Small intestine-digestion and absorption• Large intestine- reclaims water, produce vitamin
K, produce feces
How does the stomach avoid digesting itself?
• Food contact on lining stimulates gastrin to be secreted
• Gastrin targets parietal cells (to secrete HCl) and chief cells (to secrete pepsinogen)
• Pepsinogen is activated by HCl
• HCl also kills bacteria and denatures protein
The Villus: Functional Unit of the Mammalian Digestive System
• Found in the small intestine
• Contains a capillary and a lacteal
• Responsible for most absorption
• Human small intestine surface area = 300m2