Animal Nutrition Mc Donald, Greehalgh and Warner. 1987. Animal Nutrition. Longman
animal nutrition 2015 - Washington State University
Transcript of animal nutrition 2015 - Washington State University
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Animal Nutrition 1
Some of the best known and
fascinating adaptations of animals
involve their feeding and digestion
Examples:
• Reptile swallowing prey
• Baleen whales
http://www.youtube.com/watch?v=vJvfjiCTvq4
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Pythonhttp://www.youtube.com/watch?v=aDW5HpdFals
Starfishhttp://www.youtube.com/watch?v=i-EJuL0ix5Q
http://www.youtube.com/watch?v=rE8l-KFQlhY
Animal diversity of feeding strategies and digestive physiology
• Filter feeders,
predators
• Digestive systems:
no true tissues and
organs,
gastrovascular
cavity, true digestive
system (alimentary
canal)
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Simple intracellular digestion
• Example
paramecium
• Food taken up into
food vacuoles
where enzymatic
and chemical
digestion occurs
Figure 33.3 Anatomy of a sponge
Intracellular digestion by
phagocytosis in choanocyte
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Extracellular digestion
• A. outside organism
• B. gastrovascular cavities
• C. alimentary canal
Extracellular digestion
• Secrete digestive
enzymes onto
food source
• Absorb nutrients
• Best known in
fungi and
bacteria, some
higher animals
Gastrovascular
cavity: Hydra
-extracellular
digestion
-increased
surface area
-disadvantage?
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Extracellular digestion
• A. outside organism
• B. gastrovascular cavities
• C. alimentary canal
Gastrovascular cavity vs. Alimentary
Canal
Alimentary canal: a simple view
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mouth
Mechanical
digestion storage
absorption
anus
Basic parts of alimentary canal
Alimentary canal: mammalian
Mouth
• Mechanical
• Enzymatic
• Salivary amylase
– Digests starch
• Food formed into bolus
• Moistened and
dissolving with saliva
• Peristaltic contraction
to stomach
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Stomach
-muscular organ,
approx. 1 liter
capacity
-esophageal
sphincter, pyloric
sphincter
-rugae (ridges)
Digestive
mechanisms in
stomach
• Mechanical
• Chemical
• enzymatic
Mechanical
• Mixing and churning
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Digestive mechanisms
• Mechanical mixing and churning
• Chemical - pH around 2
– Also breaks food down
• Enzymatic – Pepsin (protease) breaks down
protein
• Absorption – low surface area, water, small
molecules such as ethanol, aspirin
Why doesn’t
pepsin digest
stomach?
Activation of
pepsin
-chief cells –
pepsinogen
(inactive)
-parietal cells -
HCl
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Small intestine
• Most of the
enzymatic
digestion occurs
here
• Acid neutralized
• Starch, protein,
lipids digested
Why doesn’t the small intestine digest
itself?
Fig. 37.13
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Most nutrient
absorption takes
place in small
intestine
• Structure: another
example of
increasing surface
area
Structure of
small intestine
Microvilli
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Large intestine
(colon)
• Major function is
to reabsorb water
• Rich in symbiotic
bacteria
• Bacteria digest
cellulose
• Some symbiotic
bacteria produce
vitamin K
Variations of vertebrate digestive
system
• Herbivorous mammals
– Specialized fermentation chambers