Download Advantage of pregastric fermentation

‫تغذیه دام درمرتع‬
Animal nutrition
on the rangeland
(Part 3)
By: A. Riasi
(PhD in Animal Nutrition & Physiology)
Digestive system of ruminants
 Proper care of the land and its grazing animals
requires a sound understanding of ruminant
nutrition.
 Ruminant comes from the word “rumen”.
Ruminant digestive physiology
Digestive system of ruminants
Advantage of pregastric fermentation

Make better use of alternative nutrients
 Cellulose
 NPN

Ability to detoxify some poisonous compounds
 Oxalates, cyanide, alkaloids
Advantage of pregastric fermentation
Advantage of pregastric fermentation
 More effective use of fermentation end products
 Volatile fatty acids
 Microbial protein
 B vitamins
 Decrease in handling undigested residues
 In wild animals, it allows animals to eat and run
Disadvantage of pregastric fermentation
 Fermentation is inefficient
 Energy
• Loss
Amount (% of total caloric value)
Methane
5-8
Heat of fermentation
5-6
Disadvantage of pregastric fermentation
 Fermentation is inefficient
 Protein
• Some ammonia resulting from microbial degradation will be
absorbed and excreted
• 20% of the nitrogen in microbes is in the form of nucleic
acids
Disadvantage of pregastric fermentation
 Ruminants are susceptible to toxins produced
by rumen microbes
 Nitrates
Nitrites
 Urea
Ammonia
 Nonstructural carbohydrates
Lactic acid
 Tryptophan
Methyl indole
 Isoflavonoid estrogens
Estrogen
Ruminant digestive process
• Nutrients absorbed from the digestive tract include:
• Volatile fatty acids
• Amino acids
• Fatty acids
• Glucose
• Minerals
• Vitamins
Ruminant digestive process
• Digestion begins when an animal takes a bite from
the pasture.
• As the animal chews the feed is formed into a bolus
(a packet of food capable of being swallowed).
• Saliva is excreted, which further aids in swallowing
and serves as a pH buffer in the stomach.
Ruminant digestive process
• Ammonia can be absorbed into the animal’s system
through the rumen wall, or can be consumed by
bacteria to become microbial protein.
• If adequate and suitable VFAs are present, NH3 is
incorporated into microbial protein; otherwise, it is
absorbed, particularly if the rumen pH is alkaline.
Ruminant digestive process
• Once in the rumen, the feed begins to undergo
fermentation.
• Millions of microorganisms ingest the feed, turning
out end products which serve as a major source of
nutrients for the animal.
Ruminant digestive process
• Some of the principle products formed are ammonia,
methane, carbon dioxide, and volatile fatty acids
(VFAs).