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