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An Sc 311 Midterm 2 > Lecture 10 - Ruminant Anatomy and Digestion > Flashcards

Lecture 10 - Ruminant Anatomy and Digestion Flashcards

1
Q

Phylum, class, subclass, order and suborders of ruminants

A

Cordata, mammals, ungulata (hooved), ariodactyla (even-toed)
Sub orders:
Tylopoda (pseudo-ruminants e.g. camel, llama)
Ruminantia (true ruminants e.g. cattle, deer)

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2
Q

Components of ruminant anatomy

A

Rumen, reticulum, omasum, abomasum

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3
Q

Motility in the reticulo-rumen

A

Mixing, eructation, rumination

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4
Q

On what side would you see the omasum and abomasum

A

The right side

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5
Q

Instead of villi, the rumen wall has…

A

Papillae

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6
Q

Characteristics of the rumen papillae

A
  • have highly vascularized connective tissue
  • lack smooth muscle, therefore do not move
  • cells in contact with contents are keratinized/dead
  • cell renewal takes place in stratum basale
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7
Q

Role of papillae in rumen

A

Increase surface area for absorption of SCFA from fermentation

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8
Q

Main function of the rumen

A

Large compartment for microbial fermentation

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9
Q

Characteristics of the rumen wall

A

Stratified squamous epithelium (partially keratinized)
Papillae
Sensory receptors

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10
Q

Sensory receptors of the rumen wall

A

Tension receptors: excited by passive distention
Epithelial receptors: excited by physical and chemical stimuli

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11
Q

Rumen environment

A

Moist and warm
pH 5.5 - 7.1
Gas production
Regular addition of new digesta

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12
Q

Rumen absorbs..

A

fermentation end products
- SCFA = acetate, propionate, butyrate and ammonia

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13
Q

Characteristic of the reticulum wall

A

Stratified squamous epithelium
Honeycomb appearance
Partially separated from cranial sac of rumen

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14
Q

The rumen and reticulum..

A

Are anatomically different, but operate as a combined functional unit

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15
Q

Rumen and reticulum contraction facilitates

A

Regurgitation for rumination
Mixing digesta in the reticulo-rumen
Passage of digesta to the omasum

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16
Q

What is the reticular groove

A

Conduit for milk from the cardiac opening to the reticulo-omasal opening, then through the omasum to abomasum (no need to ferment milk, it is highly digestible)
Closure of groove is a reflex initiated when receptors in the mouth/pharynx are stimulated

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17
Q

Characteristic of the omasum, its role

A

Stratified squamous epithelium, consists of many leaves (laminae)
Absorption of water and VFA

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18
Q

Role of the abomasum. Walls?

A

True stomach secreting acid (HCl) and enzymes
Mucosal epithelial cells

19
Q

**Know pics of different compartments

A

ok

20
Q

At 3 days old, the forestomach is made up mostly of… At 3 months old/ adult…

A

Abomasum at 3 days
Rumen as adult

21
Q

Sequence of motility of reticulo-rumen (mixing)

A
  1. Double contraction in the reticulum
  2. Anterior dorsal sac of rumen
  3. Caudal region of rumen
  4. Main ventral rumen
  5. Caudoventral sac
    Slide 17
22
Q

What does rumen contraction do in terms of VFA

A

Enhances absorption, mix digesta so VFA are redistributed evenly

23
Q

Where is the gas layer in the rumen? Intense fermentation occurs where? Moderate fermentation occurs where/aka?

A

Gas layer at top
Intense fermentation in middle region (fiber mat and intermediate zone)
Moderate fermentation at bottom aka liquid zone

24
Q

Sequence of steps for motility of reticulo-rumen (eructation)

A
  1. Starts in caudoventral sac
    2-4. Sweeps across the dorsum to reach vicinity of the cardia
  2. Completed with contraction of the main ventral rumen
    Slide 21
25
Q

What is eructation

A

Gas distends dorsal rumen, gas bubble pressed against cardia and is forcibly ejected into esophagus by contraction of main ventral rumen

26
Q

How does motility of reticulo-rumen work during rumination

A

Additional reticular contraction before biphasic contraction (triphasic)
Soft palate is elevated, closes nasal passage
Inspiratory muscles expand thorax
Reverse peristalsis lifts bolus into buccal cavity
Re-mastication and re-insalivation
Re-swallowing

27
Q

Why do we need to re-masticate during rumination

A

Digesta too large to enter omasum

28
Q

Daily time/periods spent ruminating

A

14 periods over 24 h
Cattle on hay = 8 h
Cattle on concentrates = 2.5 h

29
Q

How does particle size of alfalfa affect chewing time

A

Corse alfalfa has higher eating time and ruminating time than fine alfalfa

30
Q

Slide 29

A

Metabolism for VFA production

31
Q

Fermentability of starch, fiber, sugar ranked

A

Sugar > starch > fiber (slowest)

32
Q

What happens when there’s excess ruminal fermentation

A

Greater fermentation acid production (VFA, lactate)

33
Q

What determines ruminal pH

A

Balance between VFA production and buffering (saliva secretion contains buffer stimulated by rumination) capacity of rumen

34
Q

Slide 32**

A

Important

35
Q

Most SCFA are produced by… Which SCFA?

A

Microbes produce acetate

36
Q

How does high starch vs high fiber diet affect VFA production

A

High starch diet means more acetate production, more propionate production

37
Q

How do protonated vs deprotonated acetate cross the rumen epithelium

A

Deprotonated need facilitated diffusion exchange with bicarbonate
Protonated can do simple diffusion

38
Q

As rumen pH decreases what happens to propionate, acetate and lactate production

A

Acetate and propionate start to decrease around pH 5
Lactate begins to increase

39
Q

Role of acetate

A

Energy source in most tissues
Substrate for f.a. synthesis in adipose tissue/mammary gland
Not used for glucose synthesis

40
Q

Role of propionate

A

Primarily taken up by liver to produce glucose

41
Q

Role of butyrate

A

Utilized by ruminal wall as energy source, and ketones produced from butyrate in ruminal wall serve as E source and substrate for f.a. synthesis

42
Q

Directly after eating, what happens to rumen pH and total VFA?

A

Rumen pH drops, total VFA increases

43
Q

Rank good quality hay, concentrate mix/grain and poor quality hay based on digestibility

A

(most digestible) concentrate mix/grain <- good quality hay <- poor quality hay

An Sc 311 Midterm 2 (6 decks)

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