Week 1

Gastrointestinal Tracts & Nutrient Utilization

Species Specifics

Text Transcript

Time: 6.40

Follow along with the audio...

• Avian species
  • Figure 1.6 - Poultry GI tract



• Three regions of stomach
• Crop
• Proventriculus
• Gizzard
• Crop
  • Temporary storage
• Proventriculus
• Glandular stomach
• Gizzard
  • Dense pouch
  • Tough, muscular lining
  • Grit
  • Grinds ingested feedstuff
• Two large ceca
• Combined excretion of urine and feces

• Ruminants
  • Figure 1.7 - Ruminant GI tract



• Anatomy of rumen system

  • Figure 1.8 - Ruminant stomach



 

• Reticulum

  • Figure 1.9 - Interior surface of reticulum



• Honeycomb surface
• Capture dense particles
• Microbial fermentation

 

• Rumen
• Largest compartment
  • Extensive pre-digestive and pre-absorptive microbial fermentation
  • Bacteria, protozoa, and fungi
  • Population diet and intake dependent
  • Lined with papillae
    • Increases surface area and absorption
• Figure 1.10 - Interior of rumen



 

• Omasum
  • Figure 1.11 - Interior of omasum



• Membranous leaves in lumen
• Sieve large particles
• Water absorption

 

• Abomasum
• Glandular stomach
  • Largest compartment prior to rumen development

 

• Unique characteristics
  • Reticular or esophageal groove
    • Milk directly from esophagus to omasum
  • Rumen development
    • Stimulated by volatile fatty acids (VFA)
    • Lambs – 8 weeks
    • Calves – 6 to 9 months
  • Rumination
    • Regurgitation and remastication
  • Eructation
    • Emission of fermentation gases
• Rumen fermentation
  • Advantages
    • Utilization of fibrous feedstuffs
      • Hemicellulose and cellulose digestion
    • Utilization of lower quality protein and NPN
      • Conversion to higher quality protein
    • Production of water-soluble vitamins and vitamin K
  • Disadvantages
    • Reduced utilization efficiency with higher quality feeds
      • Reduced yield from digestible energy sources
      • High converted to lower quality protein