Flashcards in Digestive systems Deck (38)
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1
Three categories of mammal diets?
1. Category 1 - Faunivores (carnivores)
2. Category 2 - Frugivores (omnivores)
3. Category 3-6 - Folivores (herbivores)
2
Examples of foregut fermenters?
Ruminants, camelids, hippo, sloth, macropods (kangaroos), colobus monkey
3
Examples of hindgut fermenters?
Horse, elephant, rhino, rabbit, rat, wombat, koala
4
3 divisions of the forestomach in ruminants & properties?
1. Rumen - large, muscular, mucous membrane lining
papillae (++SA absorption)
Microbes - fungi, bacteria, protozoa
2. Reticulum - Mucous membrane lining (honey-comb appearance)
3. Omasum
5
Why are camelids considered pseudo-ruminants?
Instead of omasum, contain recessed glandular saccules in 1st compartment, and glandular mucosa in 2nd compartment
6
Compare marsupial/macropod foregut fermenters with ruminants
Ruminants ruminate while macropods ++saliva secretion thus do not need to re-chew food.
++saliva -> buffer for SCFAs produced by fermentation
7
Foregut fermenter with highest mean retention time (MRT)?
sloth
8
Rate of digestion control in ruminants...?
++fibre -> ++MRT ->++digestion of plant fibre
9
Hindgut fermenters - what is analogous to ruminant forestomach?
Caecum &/or colon
10
Why is caecum important?
Contains large bacterial pop.
However is smaller -> limited fibre digestion
11
Hindgut fermenter with highest mean retention time (MRT)?
Koala
12
Rates of digestion control in hindgut fermenters...?
++fibre -> --MRT fluids & particles
13
Define caecotrophy
Ingesting animal faeces from caecum for ++energy & microbial protein
14
A bit about koalas...?
Hindgut fermenters (caecum & colon)
Practice caecotrophy only around weaning time
15
A bit about wombats...?
Colon fermenter (60% of digestive tract)
Coarse particles retained longer by longitudinal muscle
16
Example of foregut & hindgut fermenter?
Howler monkey - 40% leaf material -> max digestion of leaf material of low digestibility
17
Carnivore digestive system...?
Stomach volume ~ 60-70% total capacity of digestive system (thus, very large) as kill/eat only once/week -> enables them to gorge quickly & digest later
Stomach -> ++HCl -> pH low -> for protein breakdown & destroy harmful bacteria on decaying flesh
SI -> short (~3-6 times body length) because meat easily digested compared to leaves etc (Herbivores SI 10 times body length)
18
Comparisons of carnivore vs herbivore GIT
Stomach - carnivore large, herbivore small
SI - carnivore small, herbivore large
Cecum - carnivore small, herbivore large
Colon - carnivore small, herbivore large
19
Why is foregut fermentation more advantageous than hindgut fermentation?
1. Because foregut fermentation precedes enzymatic digestion in SI -> utilises microbial nutrients (lost in faeces in hindgut fermenters)
2. Foregut fermenters less relient on protein quality of feed
3. Plant toxins degraded in foregut due to microbial fermentation
20
What are the disadvantages of foregut fermenters?
1. Inefficient at digesting high quality feeds
2. Fermentation of readily accessible cell contents inefficient -> energy loss via heat & gas
3. Hindgut better at digesting high quality forages -> degraded enzymatically in SI -> absorbed directly
21
List the general microbial populations in herbivores
Bacteria
protozoa
fungi
bacteriophages
methanogens
22
Name some rumen bacteria...?
Streptococcus bovis
Lactobacillus spp.
Ruminococcus albus
23
Protozoa properties...?
Prey on microbial bacteria
predominantly anaerobic ciliates & flagella
24
2 main protozoan ciliates...?
Holotrichs - soluble carbs
Entodiniomorphid protozoa -
25
Define defaunation & what happens during defaunation
Removal of protozoa from rumen -> ++bacteria -> decrease rumen [ammonia] (bacteria use ammonia as primary N source)
26
anaerobic fungi properties...?
Found in saliva & faeces
In foregut & hindgut fermenters
Degrade high-fibre plants
1st organism to begin digesting structural plant components (eg. cellulose, starch)
Produce range of hydrolytic enzymes
27
Examples of fungi
Caecomyces
Piromyces
28
Methanogens...?
Fermentation of carbs -> H (reduce CO2 & form methane) globally 50-60% methane from livestock!!
29
Starch & fibre on methanogenesis?
Starch -> decrease methane prod
Fibre -> increase methane prod
30
Mycoplasmas...?
with fungi account for 8% ruminal microbial biomass when fed poor quality feed
31
Phages...?
Play role in maintenance & diversity of bacterial communities ie regulate density of pops.
Found in foreguts of macropods (roos)
32
Examples of bacteria in horses?
Ruminococcus flavefaciens
Fibrobacter spp.
33
If fermentation rate in rumen is rapid?
Lactic acid accumulates
34
Fates of lactate...?
-> blood glucose
-> ruminal acidosis -> decrease fibre digestion -> decrease feed intake -> death
-> decrease pH ( decrease microbial protein synthesis
35
Describe microbial protein synthesis
Microbes hydrolyse dietary proteins -> AAs & NH3 -> NH3 primary N source for microbial protein synthesis -> out of rumen -> absorbed & digested in SI as a source of protein for animal
36
Why is microbial protein synthesis so important to ruminants? What is it affected by?
Major source of AAs (~66%)
Turnover & lysis of bacteria
Predation on bacteria by protozoa
digestibility of organic matter in intestines
37
Growth of rumen bacteria depends primarily on...?
Availability of ATP
38
