Animal nutrition

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Animal nutrition

• Chapter 41

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Function

• 1. Digestion
• 2. Absorption of nutrients/water
• Energy
• Growth
• 3. Elimination

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Mechanicaldigestion
INGESTION
Chemicaldigestion(enzymatichydrolysis)
DIGESTION
Nutrientmoleculesenterbody cells
ABSORPTION
Undigestedmaterial
ELIMINATION
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Heterotrophs
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Intracellular digestion
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Extracellular digestion
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Extracellular digestion
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Fig. 41-9
Crop
Gizzard
Intestine
Esophagus
Pharynx
Anus
Mouth
Typhlosole
Lumen of intestine
(a) Earthworm
Foregut
Midgut
Hindgut
Esophagus
Rectum
Anus
Crop
Mouth
Gastric cecae
(b) Grasshopper
Stomach
Gizzard
Intestine
Mouth
Esophagus
Crop
Anus
(c) Bird
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Digestive system
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General structure

• Gastrointestinal tract (tube)
• Mucosa inner layer (epithelial)
• Submucosa connective
• Muscularis 2 layers of muscle
• Serosa outer layer (connective)
• Plexues nerves located in the submucosa

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Digestive organs

• Mouth
• Pharynx
• Esophagus
• Stomach
• Small intestine (duodenum, jejunum, ileum)
• Large intestine (cecum, ascending colon,
  transverse colon, descending colon, sigmoid,
  rectum, anus)

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Digestive organs

• Accessory organs
• Liver
• Gallbladder
• Pancreas

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Digestion

• Mouth
• Teeth
• Gizzard (in birds to help grind food)
• Salivary glands
• Secrete saliva
• Amylase (enzyme to breakdown starch)

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Mouth
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Salivary glands
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Digestion

• Chew or mastication
• Tongue pushes food
• Pharynx
• Epiglottis closes
• Esophagus

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Pharynx
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Esophagus

• Esophagus
• Muscular tube
• Connects pharynx to stomach
• Peristalsis
• Rhythmic movement of muscle contractions
• Moves food along
• Esophageal sphincter
• End of esophagus keeps food in stomach

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Stomach

• Mucosa lining (epithelial)
• Parietal cells
• Secrete H Cl ions
• Chief cells
• Secrete pepsinogen
• Pepsinogen is converted to pepsin
• Digests proteins

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Stomach

• Gastric juices
• HCl, pepsinogen mucus pH2
• Chyme
• Mixture of partially digested food

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Stomach
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Stomach
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Small intestine

• Chyme
• Leaves stomach via pyloric sphincter
• Duodenum
• Digestive enzymes from pancreas
• Bile from liver gallbladder
• Most digestion occurs in the duodenum jejunum

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Intestines
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Small intestine
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Small intestines

• Villi along intestine epithelium
• Microvilli
• brush border
• Aids in absorption
• Secretes enzymes
• Break disaccharides (sucrose, lactose)

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Small intestine
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Accessory organs
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Accessory organs

• Pancreas
• Secretes fluids via pancreatic duct
• Exocrine system
• Trypsin chymotrypsin (proteases)
• Amylase (starch)
• Lipase (fats)
• Bicarbonate (neutralizes HCl)
• Endocrine (insulin and glucagon)

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Accessory organs

• Liver
• Secretes bile
• Contains bile pigments bile salts
• Bile pigments are waste from break down of RBC
• Eliminated

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Accessory organs

• Bile salts
• Emulsify the fats
• Bile made in liver
• Stored in gall bladder
• Released when eat fatty meal
• Gallstones can block release

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Small intestines

• Monosaccharides, aa are transported to the blood
  capillaries
• Hepatic portal vein
• Liver
• Heart
• Transported to body

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Small intestines

• Fatty acids monoglycerides
• Villi
• Triglycerides
• Chylomicrons (triglyceride protein coat)
• Lymph system

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Fig. 41-15b
Microvilli (brushborder) at apical(lumenal)
surface
Lumen
Bloodcapillaries
Epithelialcells
Basal surface
Epithelial cells
Lacteal
Lymphvessel
Villi
Key
Nutrientabsorption
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Fig. 41-16
Triglycerides
Lumenof small intestine
Monoglycerides
Fatty acids
Epithelialcell
Triglycerides
Phospholipids,cholesterol,and proteins
Chylomicron
Lacteal
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Essential nutrients
Carbohydrate digestion
Protein digestion
Nucleic acid digestion
Fat digestion
Oral cavity,pharynx,esophagus
Disaccharides
Polysaccharides
(starch, glycogen)
(sucrose, lactose)
Salivary amylase
Smaller polysaccharides,maltose
Stomach
Proteins
Pepsin
Small polypeptides
Lumen ofsmall intes-tine
DNA, RNA
Fat globules
Polysaccharides
Polypeptides
Pancreatic amylases
Pancreatic trypsin andchymotrypsin
Pancreatic nucleases
Bile salts
Maltose and otherdisaccharides
Fat droplets
Nucleotides
Smallerpolypeptides
Pancreatic lipase
Pancreatic carboxypeptidase
Glycerol, fattyacids, monoglycerides
Amino acids
Epitheliumof smallintestine(brushborder)
Small peptides
Nucleotidases
Nucleosides
Disaccharidases
Dipeptidases, carboxypeptidase,and aminopeptidase
Nucleosidasesandphosphatases
Nitrogenous bases,sugars, phosphates
Monosaccharides
Amino acids
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Large intestines

• Absorbs water
• Absorbs vitamin K
• Concentrates wastes
• E. coli
• Feces
• Cloaca
• Combines feces urine wastes in some animals

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Large intestine
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Large intestine
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Veins to heart
Hepatic portal vein
Lymphatic system
Liver
Absorbed food(except lipids)
Absorbedwater
Mouth
Stomach
Lipids
Esophagus
Small intestine
Anus
Secretionsfromsalivaryglands
Secretionsfromgastricglands
Secretions from liver
Rectum
Largeintestine
Secretions from pancreas
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Food

• BMR
• Basal metabolic rate
• Obesity
• Heart disease, diabetes, stroke
• Anorexia, Bulimia

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Essential nutrients

• Essential aa
• Minerals
• Vitamins
• A, B-complex, C, D, E, K
• Scurvy, rickets, pernicious anemia, bleeding

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Abnormalities

• Ulcers
• H. pylori
• Bacteria
• Treated with antibiotics
• Reflux
• Gastric juices go backwards to esophagus

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Hiatal hernia
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Pyloric Stenosis
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Colon Cancer
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Jaundice