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FA1 Physiology/Microanatomy 1 > Lecture 43 11/28/23 > Flashcards

Lecture 43 11/28/23 Flashcards

1
Q

What is fermentation?

A

chemical breakdown of a substance by microorganisms

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2
Q

Where does fermentation occur in foregut fermenters?

A

distinct compartments of the non-glandular stomach

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3
Q

Where does fermentation occur in hindgut fermenters?

A

cecum and colon

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4
Q

What environmental characteristics are needed for fermentation?

A

-neutral pH
-slow motility
-ability for microbes to survive and grow

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5
Q

What types of microorganisms are found in the rumen?

A

anaerobic bacteria, fungi, and protozoa

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6
Q

What are the interactions observed between the rumen microbes?

A

-waste of one organism is food for another
-synergistic digestion/microbes digest different things
-one microbe produces vitamins needed to promote the growth of others

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7
Q

Which substrates from plant cell walls can be broken down by microbes?

A

-cellulose
-hemicellulose
-pectin

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8
Q

Which substrate from plant cell walls cannot be broken down by microbes?

A

lignin

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9
Q

How does plant age impact lignin amounts?

A

plants accumulate more lignin with age

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10
Q

What happens to proteins and carbohydrates in ruminants?

A

rumen microbes use the same substrates that the host would use, potentially reducing digestion/absorption effeciency

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11
Q

What are the characteristics of volatile fatty acids?

A

-major fermentative end products
-main energy source for ruminants
-absorbed in reticulum and omasum

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12
Q

What are the main VFAs?

A

-acetate
-propionate
-butyrate

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13
Q

What are the characteristics of a high-fiber diet?

A

-higher acetate and lower propionate
-less total VFAs
-higher rumen pH

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14
Q

What are the characteristics of a high-starch diet?

A

-lower acetate and higher propionate
-more total VFAs
-lower rumen pH

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15
Q

What are the characteristics of protein fermentation?

A

-amino acids are deaminated by gut microbes
-produce ammonia and VFAs
-act as energy source for the synthesis of microbial proteins

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16
Q

Why is microbial protein synthesis important?

A

ruminants rely on it to meet their protein requirements

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17
Q

When is microbial protein production most efficient?

A

when growth rate of the microbial mass is maximized

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18
Q

Why is it important to have a balance of proteins and glucose?

A

to ensure proper energy for both protein synthesis & cell growth and cell maintenance

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19
Q

Which substrates can be used by rumen microbes to produce proteins besides other proteins?

A

-ammonia
-urea
-nitrates

20
Q

What are the characteristics of urea recycling?

A

-hepatic urea originates from ammonia produced during protein metabolism by bacteria and the body
-urea can be secreted into urine or the rumen

21
Q

What happens to urea in the rumen?

A

-converted into ammonia
-enters nitrogen pool for microbial synthesis
-allows ruminants to efficiently conserve protein and nitrogen

22
Q

What are bypass proteins?

A

-proteins that pass through the forestomachs and into the intestine
-digested and absorbed in a similar fashion to monogastric proteins

23
Q

What conditions are needed for optimal fermentation?

A

-adequate substrate provided
-appropriate temp., molality, and oxygen conc.
-removal of indigestible waste
-absorption of VFAs
-buffering of acidic pH

24
Q

What is the path through the rumen?

A

-esophagus
-reticulorumen
-omasum
-abomasum
-duodenum

25
Q

What are the layers of ingesta in the rumen?

A

-gas cap
-raft
-rumen liquors

26
Q

What are the three main types of rumen contractions?

A

-mixing
-eructation
-regurgitation

27
Q

What are the characteristics of mixing contractions?

A

-keep rumen contents well-mixed
-last 30-50 seconds

28
Q

What are the characteristics of eructation contractions?

A

-allow for CO2 and methane build up in rumen to escape
-stretch receptors signal vagal afferents

29
Q

What are the characteristics of bloat?

A

-obstruction in esophagus prevents gas eruption
-caused by diets high in saponins and/or grains that lead to dextrin slime production

30
Q

What are the characteristics of regurgitation contractions?

A

-bring large particles into mouth for additional chewing
-initiated by presence of rumen raft
-stimulates saliva secretion
-occur every 2-3 minutes

31
Q

How does diet type affect regurgitation?

A

-high grain diets have smaller particles and require less regurgitation
-high forage diets require more regurgitation

32
Q

What are the characteristics of dilution rate?

A

-rate of liquid flow through the rumen
-% of total liquid leaving the rumen per hour
-must be replaced by more liquid

33
Q

Why is a high fluid flow beneficial?

A

it washes away existing microbes and stimulates growth of new microbes

34
Q

Which signals provide control over rumen motility?

A

-stretch/distension
-ingesta consistency
-pH
-VFA conc.
-ionic strength

35
Q

How does raft size relate to rumen contractions?

A

-smaller rafts lead to less resistance to contraction and reduced muscle tension/motility
-larger rafts lead to more resistance to contraction and increased muscle tension/motility

36
Q

What are the characteristics of pH?

A

-slightly acidic due to VFA production
-hyperacidity suppresses rumen motility

37
Q

What are the main characteristics of hindgut fermentation?

A

-smaller particle size to start
-digestible carbohydrates and protein are already mostly absorbed

38
Q

What are the functional segments of the hindgut fermenter’s colon?

A

-cecum
-ventral colon
-dorsal colon
-small colon

39
Q

What is the goal of haustral segmentation motility?

A

promotes mixing and brings VFAs in contact with mucosa for absorption

40
Q

What is the goal of propulsive peristalsis?

A

moving ingesta aborally

41
Q

What are the functions of retropulsive peristalsis?

A

-retaining ingesta for more mixing
-allowing microbes to remain in colon instead of being flushed out
-allowing small particles to pass while retaining large particles

42
Q

Where does retropulsive peristalsis occur?

A

distal left and distal right ventral colon

43
Q

What is the pelvic flexure?

A

an area of narrowing in the distal left ventral colon that is prone to impactions

44
Q

What are the characteristics of buffering?

A

-ileum secretes large amounts of bicarb. and phosphate buffers
-high VFA conc. stimulates water secretion by large intestine crypt cells

45
Q

What is cecotrophy?

A

act in which hindgut fermenters consume fecal pellets for a “second chance” at the nutrients

FA1 Physiology/Microanatomy 1 (46 decks)

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