export_ruminant nutrition Flashcards
4 Stomach compartments of a ruminant?
reticulum; rumen; omasum; abomasum
Primary site of microbial digestion?
rumen
Purpose of honeycomb structure in reticulum?
acts as sieve and prohibits larger particles from moving further down the digestive tract
Primary organ of rumination?
reticulum
Purpose of Rumination (3)
ingest feed rapidly and chew later; reduce particle size so microbes can better utilize forage; increase saliva production
Saliva is rich in:
sodium, phosphate, and bicarbonate
Major source of buffering by neutralizing the acids produced during fermentation?
Bicarbonate
Main function of ruminal papillae?
absorb VFAs
Acts as a pump to transfer digesta from reticulum to abomasum?
omasum
Absorbs water, VFAs, and bicarbonate
Omasum
“true stomach”
absomasum
Stomach wall secretes enzymes (HCl, pepsinogen, zymogen prorennin) in which compartment?
abomasum
Order of substance in rumen top to bottom?
gas (CO2, CH4); fiber mat; fluid fraction
Fluid Fraction Components:
bacteria, protozoan, fungi
pH of fiber digesters?
6.2-6.8
Which rumen digesters respond slowly to change?
fiber digesters
Starch digesters like pH of what?
5.2-6
Which ruminal digesters respond quickly to change?
starch
Ruminal microbes from most abundant to least?
Bacteria, protozoa, fungi
What happens to rumen protozoa if pH is below 5.5?
population is wiped out but does not change performance of animal
T or F: Rumen fungi decrease in numbers in cattle on high fiber diets.
False; increase
T or F: Rumen fungi are anaerobic.
True
Non-structural Carbohydrate Components?
simple sugars; starches; fructans; organic acids
Structural Carbohydrates
cellulose; hemicellulose; pectin; lignin
Difference in bonding between non-structural and structural carbohydrates?
non-structural = alpha structural = beta
Starch (ruminant) molecules are digested by:
microbial or mammalian enzymes
Cellulose (ruminant) molecules are digested by:
microbial cell secretion of microbial enzymes
VFA importance to animal
energy for growth, repro, lactation
VFA importance for microbes
cell growth and division
VFAs come from?
microbial enzymes attacking carbs to give simple sugars and then VFAs
Product of microbial fermentation
VFAs
Major site of absorption of VFAs
rumen wall
Majority of ruminant energy comes from:
VFAs
3 Main VFAs
acetic acid, proprionic acid, butyric acid
Major VFA
acetic acid
Main precursor for lipogenesis
acetic acid
VFA oxidized throughout most of the body to generate ATP
Acetic acid
VFA essential for milk fat?
Acetic Acid
Major product of fiber digesting bacteria?
acetic acid
VFA produced by starch fermenters
proprionic acid
VFA that provides energy by being converted to glucose in the liver?
Proprionic Acid
VFA converted to ketones during absorption through the rumen epithelium and is oxidized in many tissues for energy production
Butyric Acid
VFA that provides energy to rumen wall
Butryic Acid
Crude protein
a measure of the total amount of nitrogenous compounds in a feedstuff
Undegradable Intake Protein
fraction of total protein that escapes rumen degradation; arrives at small intestine
Portion of feed protein that arrives at small intestine and escapes rumen degradation?
undegradable intake protein
Fraction of total protein that is degraded or broken down in rumen?
Degradable intake protein
2 fates of ruminal protein?
go to small intestine and be used by rumen; stay in rumen and be used by microbes
Microbial use of protein?
protein synthesis; fermentation
Important source of N
free ammonia
What helps to maintain a fairly constant protein quality supply to lower digestive tract?
nitrogen recyclin
T or F: Forages with a TDN:CP ratio of >7 do not require and protein supplementation.
False
Importance of low TDN:CP ratio?
results in better digestibility and higher intakes of forages
Associative Effects
difference between response to a combo of feedstuffs and the sum of the responses to the individual feedstuffs (difference between observed and predicted)
Reason for a positive associative effect?
additional feedstuff may provide protein which increases intakes and utilization of lower quality forages (more protein to microbes = more efficient digestion)
Decreasing pH will cause a negative associative effect because:
decrease pH limits growth of digesting bacteria
End product inhibition
increase of sugars may inhibit activity or synthesis of enzymes involved in fiber degradation
Competition for nutrients - negative effect
starch or sugar fermenters may out compete fiber digesters for nutrients
Lipids
triglycerides; glycolipids and phospholipids
Triglycerides are metabolized into:
glycerol and FAs
Glycolipids are metabolized to:
galactose and FAs
Phospholipids are metabolized to:
glycerol and FAs
Glycerol and galactose are fermented by microbes resulting in:
VFAs
What happens to ruminants in the case of excess dietary fat?
depress fiber digestion
Where is the majority of SA in adult ruminant located?
rumen
Where is the majority of SA in calf?
true stomach (abomasum)
Why do ruminants do well on forage diet?
can break down beta chemical bonds