2. GI Part 9 Flashcards
where doe fermentative idgestion occur
specialized compartments localized before the stomach (forestomach in ruminants) or after the stomach and small intestine (cecum and colon in horses)
what kind of microbes are responsible for fermentative digestion
bacteria
fungi
protozoa
what origin are enzymes of
microbe origin
what is associated with fermentative digestion
regurgitation and remastication of food in order to provide more finely divided material and thereby a greater surface area for microbial digestion
what side of the animal is the rumen on
what is the reticulum close to
rumen is on left side of animal
reticulum is close to the heart
what do the pillars of the rumen do
separate the sacs of the rumen
can move, play an important role in mixing of digesta
what are the forestomachs lined with
stratified squamous epithelium
what is considered the true stomach and what side is it mostly on
abomasum
mostly on right side of animal
what is the largest compartment in the newborn ruminants stomach
abomasum
describe forestomach development after birth
enlargement of the forestomach occurs rapidly after birth, but rate depends on diet type and contact with adult ruminants
solid feeds accelerate development
inoculation of microorganisms from adult ruminants
nonruminant period – birth to 3 weeks
transitional period – 3-8 weeks
describe rumen protozoa
most are ciliated and belong to genus Isotricha or Entodinium
grouped by size – big, medium, small
grouped by morphology – flagellates, ciliates
ruminal environment: substrate availability temperature fluids pH osmolality
substrate availability – food intake regulated by volume, structure, energy, palatability
temperature – about 0.5-1 degree C above body temperature
fluids – drink water and saliva
pH - 5.5-7 (acid synthesis and acid reabsorption, buffer substances coming from saliva and rumen epithelium)
osmolality – 260-400 mOsm/L
describe the ruminal ecosystem
protozoa ingest large numbers of bacteria and hold bacterial number in check
protozoa may also play a role in starch and protein digestion
how do protozoa play a role in starch and protein digestion in the rumen
prolong digestion of these substances – ingest them and protect them from bacterial action
describe the syntropy (symbiosis) of the rumen
the waste products produced by one species serve as a substrate for another
for example cellulose digestion by species A produces a waste that species B uses to digest protein
protein digestion by species B produces a waste that species A uses to digest cellulose
ruminal layers
top — gas
fiber mat (intense fermentation)
intermediate zone (intense fermentation)
bottom – liquid zone (moderate fermentation)
what are VFAs form carb, protein, and fat digestion by rumen microbes used for
propionate – goes to liver and is used for glucose synthesis by gluconeogenesis
acetate and butyrate g– o to all tissues and are used for energy
acetate – goes to adipose tissues to create fatty acids
what do cell walls of plants have and why is it important
has a large portion of carbohydrates which are important for stability and rigidity of the growing plant (structure carbs)
what are some plant carbs
cellulose
hemicellulose
pectin
what enzyme hydrolyses cellulose, hemicellulose, and pectin
cellulase
what happens to cellulose, hemicellulose, and pectin after hydrolysis
after hydrolysis, monosaccharides are released from the polysaccharide
are the monosaccharides released from cellulose, hemicellulose, and pectin after hydrolysis available for absorption by the animal
no they are not
they are further metabolized by the microbes
what are the products of protein and carb fermentative digestion in the forestomachs
what happens to these products
glucose
other monosaccharides
short chain polysaccharides
these products are no available to host animals, they are absorbed into the cell bodies of the microbes
what happens to glucose within the microbial cell and what does it produce
glucose enters the glycolytic pathway to produce 2 pyruvate from one glucose molecule (plus 2 NADH and 2 ATP which is used by the microbes)
what type of digestion is fermentative digestion and what are the products
anerobic
products are VFA (SCFA)
what are the primary VFA
acetic acid (acetate)
propionic acid (propionate)
butyric acid (butyrate)
pathway of VFA production by the rumen and products – acetate
glucose –> pyruvate –> acetyl CoA –> acetate
products
4 ATP; 4 NADH/FADH2; 0 O2
pathway of VFA production by the rumen and products – butyrate
glucose –> pyruvate –> acetyl CoA –> butyrate
products
3 ATP; 2 NADH/FADH2; 0 O2
pathway of VFA production by the rumen and products – propionate
glucose –> pyruvate –> propionate
products
4 ATP; 0 NADH/FADH2; 1 O2
pathway of VFA production by the rumen and products – propionate + acetate
glucose –> pyruvate –> lactate –> propionate + acetate
products
3 ATP; 0 NADH/FADH2; 0 O2
