Nutrition and Digestive Physiology

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Nutrition and Digestive Physiology

• Dr. Mickey A. Latour
• Purdue University
• West Lafayette, IN 47907

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Livestock Feeding

• Roughage high fiber, low energy
• Concentrate low fiber, high energy

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How is a ration balanced?

• Pearson square balance a ration using any two
  ingredients for one nutrient
• How much Soybean Meal (44 Protein) should be
  mixed with Barley (13 Protein) to get a mixture
  that is 16 protein?

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Pearson Square
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Pearson Square

• Soybean Meal 3 parts
• Barley 28 parts
• Total Parts 31
• Soybean Meal 3/31 or 10
• Barley 28/31 or 90
• If mixing a ton (2000) SBM 200, Barley 1800

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Digestion

• Overview of digestion
• Overview of the enzymatic, hormone and cellular
  processing of nutrients
• How do animals utilize the nutrients they consume
  and furthermore, is the process different between
  animals?

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Digestion

• There are four steps in digestion

A) digestion B) absorption C) circulation of
absorbed nutrients D) cellular metabolism
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What are Nutrients?

• Parts of food which provide for growth,
  maintenance, body functions
• Carbohydrates (CHO)
• Fats
• Proteins
• Vitamins
• Minerals
• Water

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What is a Ruminant?

• Animals with more than one stomach compartment
• Chew their cud (re-chew food)
• Cows, sheep, goats
• Cows have four stomach compartments

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Why dont cattle need as much B vitamins?

• Microorganisms in the stomach of the cow make
  their own B vitamins
• Can also make some proteins if given the right
  kind of Nitrogen (nitrates, urea)

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NonRuminants

• Foragers Horse, rabbit
• NonForagers pig, poultry

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Digestive System

• Large complex molecules broken down into simpler
  molecules
• Long tube beginning with mouth and ending with
  the anus

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Digestion (Nonruminant)

• Swine, Poultry, Fish and to some extent young
  calves and lambs are functionally nonruminants
  until the accessory stomach compartments develop
  (several months).

• Nonruminant or monogastric have the following
  pathway for
• digestion.

Food---Mouth-Esophagus-Stomach--Small
Intestine---Large Intestine- Rectum---Anus
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Digestion

• Food/Mouth

A) The food is considered a bolus and the act
of putting food in the mouth is called
prehension. B) Mouth is where chewing occurs to
increase the surface area of food which aids
in the digestion process.
C) Salvia is produced by stimuli received from
the para- synpathic nervous system and
causes potassium, bicarbonate ion release.

Movement through this pathway is accomplished by
peristalis

• Esophagus is the passage way from the mouth to
  the stomach.

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Digestion

• Stomach (Gastric 3 phases)

A) Small amounts of pepsinogen are released and
the stomach become acidified through the
hormone gastrin.
Three phases of Gastric secretion
1) Cephalic phase (the sight and smell of
food) 2) Gastric phase (presence of food in the
stomach) 3) Intestinal phase (presence of food
in the upper small intestine)
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The Stomach
Figure 24.12b
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Stomach Lining
Figure 24.13c, d
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Digestion

• Small Intestine

- Once food enters the small intestine a number
of hormones are stimulated - Hormones a.
Secretin----stimulates pancreas to release
enzymes b. Gastric inhibitory peptide
c. Vasoactive intestinal peptide d.
Somatostatin e. Cholecystokinin
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Small Intestine

• Important digestive and absorptive functions
• Secretions and buffers provided by pancreas,
  liver, gall bladder
• Three subdivisions
• Duodenum
• Jejunum
• Ileum
• Ileocecal sphincter
• Transition between small and large intestine

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Intestinal Wall
Figure 24.17b, c
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Intestinal Wall
Figure 24.17d, e
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Functions of the Large Intestine

• Reabsorb water and compact material into feces
• Absorb vitamins produced by bacteria
• Store fecal matter prior to defecation

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The Gallbladder

• Hollow, pear-shaped organ
• Stores, modifies and concentrates bile

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Gallbladder
Figure 24.21a, b
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Digestion

• Bile acids do two things

1) Emulsify fat into small particles and targeted
for absorption
2) A means for excretion of waste products
(i.e., biliruben)
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Digestion

• Large Intestine

a) Active absorption of electrolytes and water
b) Tremendous amount of bacterial action to make
certain vitamins (K, B12, thiamin,
riboflavin)
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• Horse Rabbit
• Ruminant digestive differences

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Digestion in Horse and Rabbit

• Not classified as a ruminant or nonruminant

• Digestion and absorption is somewhat similar to
  nonruminants
• through the small intestine.

• The real difference exist in the large
  intestine (cecum, large colon,
• small colon, rectum, and anus) where they can
  store 35 gallons
• of ingested food. This volume size coupled
  with time provides
• an excellent site for bacterial action and
  the liberation of nutrients.

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Digestion

• Ruminant (Cattle, Sheep, Goat) Very important,
  since they convert grasses material into
  products.

• Rumination involves the process of
  regurgitation, reensalivation,
• and remastication and reswallowing of ingested
  rumen materials.

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Digestion

• Mature ruminant has 4 functional stomach
  compartments
• 1) Rumen
• 2) Reticulum

3) Omasum 4) Abomasum

• Rumen is the largest segment and provides a
  near ideal environment
• for microorganisms. The organisms in turn
  provide the following

a) convert large amounts of starch and cellulose
to volatile fatty acids b) convert both protein
and nonprotein nitrogen into amino acids c)
synthesize Vitamin K, and all B complexes
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Digestion

• Reticulum is the site of fermentation of
  ingested materials and
• commonly referred to as the honeycomb where
  there is great
• filtering of ingested materials between the
  rumen and omasum.

• Omasum can further crush materials and grind
  them into small
• pieces.

• Abomasum functions like a true stomach
  nonruminant

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Organs
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The Pancreas

• Pancreatic duct penetrates duodenal wall
• Endocrine functions
• Insulin
• Exocrine functions
• Majority of pancreatic secretions
• Pancreatic juice secreted into small intestine
• Carbohydrases
• Lipases
• Proteolytic enzymes

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The Liver

• Performs metabolic and hematological regulation
  and produces bile
• Histological organization
• Lobules containing single-cell thick plates of
  hepatocytes
• Lobules unite to form common hepatic duct
• Duct meets cystic duct to form common bile duct

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Anatomy of the Liver
Figure 24.19b, c
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Liver lobule is the basic functional unit of the
liver

• Hepatocytes form irregular plates arranged in
  spoke-like fashion
• Bile canal carry bile to bile ductules
• Bile ductules lead to portal areas

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Liver Histology
Figure 24.20a, b