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Nutrition exam 3 > Rumen physiology > Flashcards

Rumen physiology Flashcards

1
Q

what does ruminare mean

A

to chew over again (latin)

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2
Q

why is the cud not acidic

A

comes from the first and second compartments that have a more neutral pH

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3
Q

true v. pseudoruminants

A
  • true: 4 compartment stomach

- pseudo: 3 compartments (no omasum)

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4
Q

2 theories of ruminant evolution

A
  • “eat and run”

- detoxification of plant substances

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5
Q

what % of digestion do ruminant microbes account for

A

70%

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6
Q

does rumen wall secrete enzymes or not?

A

no

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7
Q

functions of rumen (4)

A
  • storage
  • soaking
  • physical mixing and breakdown
  • fermentation
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8
Q

what does pregastric fermentation consist of (3)

A
  • bacterial synthesis of water soluble vitamins and vitamin k
  • bacterial synthesis of amino acids and protein
  • breakdown of fibrous feeds
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9
Q

what is wall of reticulum lined with? does it secrete enzymes?

A
  • lined with mucous membrane

- no enzymes

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10
Q

function of reticulum

A

moving ingested feed into rumen or omasum

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11
Q

what is omasum filled with

A

muscular laminae

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12
Q

function of omasum

A

reduce particle size of ingesta

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13
Q

is abomasum glandular or nonglandular

A

glandular

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14
Q

where does reticular (esophageal) groove extend from

A

cardia to omasum

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15
Q

steps in rumination (4)

A
  • regurgitation
  • remastication
  • resalivation
  • reswallowing
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16
Q

eructation

A

elimination of CO2 and CH4 (endproducts of fermentation)

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17
Q

advantages of pregastric fermentation (6)

A
  • utilization of cellulose as energy source
  • conversion of NPN to microbial protein
  • N recycling
  • microbial detox of plant compounds
  • reduction of B-vitamin req
  • absorption of microbial end products
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18
Q

disadvantages of pregastric fermentation (3)

A
  • can lose energy from fermentation as heat, methane
  • amino acid balance may not be improved
  • many drugs can’t be fed orally
19
Q

is the rumen oxidating or reducing

A

reducing

20
Q

what is rumen rich in and deficient in

A
  • rich in organic matter

- deficient in readily metabolizable compounds

21
Q

range of DM % of rumen contents

A

7-15%

22
Q

what % of body weight does rumen comprise of

A

7-15%

23
Q

what % of total stomach volume is rumen

A

80-85%

24
Q

does rumen secrete digestive juices

A

no

25
Q

how are end products/wastes from fermentation removed

A

diffusion across rumen wall

26
Q

2 mechanisms for keeping rumen pH near neutrality

A
  • continuous influx of saliva (phosphate-bicarb buffer, some urea/mucous, no enzymes)
  • diffusion across rumen wall (more VFA diffuse into blood than omasum)
27
Q

rumen temperature

A

34-40 C, may be as high as 41 in active fermentation

28
Q

rumen gases

A
  • CO2 (65%)
  • CH4 (27%)
  • H2 (0,2% –> used to reduce CO2 to CH4)
  • N (7%)
  • trace H2S, O2
29
Q

rumen facultative anaerobic bacteria

A

O2 scavenging activity to maintain anaerobic conditions

30
Q

how does urea enter rumen

A

feed supplement, saliva, diffusion across rumen wall –> source of NH3

31
Q

what bacteria have higher urease activity

A

adherent bacteria (also scavenge O2)

32
Q

ecological niches

A
  • liquid phase: free-living microbial groups in fluid (25%)
  • solid phase: microbial groups w/ food particles (70%)
  • rumen epithelium: microbial groups attach to animal cells (5%)
33
Q

growth of microbes adhered to feed particles

A
  • net growth rate less than liquid dilution rate

- growth rate related to solids turnover

34
Q

growth of microbes adhered to rumen wall

A

relatively slow net growth rate

35
Q

rumen microbial population (5)

A
  • bacteria
  • archae
  • ciliated protozoa
  • flagellated protozoa
  • fungi
  • bacteriophage
36
Q

functions of bacteria (9)

A
  • cellulolytic
  • amylolytic
  • hemicellulolytic
  • pectinolytic
  • ureolytic
  • proteolytic
  • methanogenic
  • glucolytic
  • lipid utilizers
37
Q

what does rumen hydrolyze fatty acids (triglycerides) into

A

free fatty acids, glycerol

38
Q

biohydrogenation

A
  • follows hydrolysis or lipolysis
  • caused by rumen microbes
  • addition of H to fatty acids with double bonds
  • converts all double bonds –> saturated FA
39
Q

synthesis of lipids

A

odd-carbon chain and branched-chain FA

40
Q

how does most fat enter SI

A

as non-esterified FA that are highly saturated

41
Q

effects of defaunation (removing protozoa)

  • VFA concentration:
  • acetate/butyrate concentration:
  • propionate concentration:
  • ammonia concentration:
  • lactic acid concentration:
  • bacterial numbers:
  • protein degradation:
  • cellulose digestion:
A
  • VFA concentration: dec
  • acetate/butyrate concentration: dec
  • propionate concentration: inc
  • ammonia concentration: dec
  • lactic acid concentration: inc
  • bacterial numbers: inc
  • protein degradation: dec
  • cellulose digestion: dec
42
Q

role of fungi

A
  • synthesize enzymes
  • more effective in cellulose digestion
  • enterases (not in bacteria) for hemicellulose/ligin
  • penetrate plant cuticle
  • pectin degradation
  • grain digestion
  • choline synthesis
43
Q

relationship between ruminal bacteria and fungi

A

inverse relationship (bacteria produce bacteriocin-like substance to inhibit fungi)

Nutrition exam 3 (8 decks)

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