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Flashcards in Lecture 2 Deck (40):
1

What cycle is the main eructation cycle?

Secondary Cycle

2

When does erructation occur?

At the end of the caudal to cranial contraction of the ventral sac

3

Explain the secondary cycle

Moves gas in rumen towards cardia

Animal inhales and creates negative pressure in thorax which draws gas into esophagus

Cranial to Caudal movement in ventral sac then caudal to cranial movement in dorsal sac

4

Explain Eructation

Microbes produce gas

Gas build up occurs in dorsal rumen

Secondary contraction moves gas to the cardia region of reticulum

Gas causes reflex opening of cardia and caudal esophagus

Animal inhales creating negative pressure in thorax drawing gas into esophagus

Some gas exhaled directly some enters lungs to be exhaled on next breath

 

5

What can occur to gas during eructation

Can be absorbed into blood

ie. ketones in blood

6

What feed increases rumination?

High-roughage diets

- have to break it down more

7

WHat is rumination and indicator of?

Good Health

8

What is released during rumination?

Endorphins

9

Sequence of events of rumination

Just before primary contraction, reticulum contracts

Negative pressure created by inhalation while airways are closed

Cardia and distal esophageal sphincter relax, drawing cud into esophagus

Esophagus contracts cranially (rvs peristalis) cud travels toward mouth

Tongue raised and squeezes fluid out of cud and fluid swallowed

Solid cud is chewed for 10-60sec

10

Two outcomes of rumination

Buccal receptor stimulation 

- increased salivation and rumen movement

- More mixing of ingesta

Smaller particle size

- Greater surface area for microbes

- Greater chance of passing omasum

11

5 Ways to examine rumen motility

Examine rate and strength of contractions

Visual exam

Auscultation

External Palpation

Rectal Exam

12

What do we look for upon a visual exam

See undulations of L. Paralubar fossa

Look for bloat

13

What do we ausculatate for?

Loud primary cycle

Fluid Splashing - Occurs at onset of bloating

Tinkling or tinging - definite indication of bloat

14

What do we externally palpate for

Doughy feel = healthy

15

What do we feel for upon rectal examination?

Feel caudodorsal rumen contractions

16

What is hypomotility?

Less than normal motility

17

What is atony or stasis?

No motility

18

Distinguish between primary and secondary clinical signs

Primary - something wrong with rumen

Secondary - Other part of body in pain

19

5 mechanisms of decreased motility

Direct Depression of gastric center

Decrease stimulatory inputs from peripheral receptors to gastric center

Increase inhibitory inputs from peripheral receptors to gastric center

Failure of neuromuscular transmission

Increased sympathetic stimulation

20

10 Conditions causing decreased motility

Animal is not eating

Displaced Abomasum

Traumatic Reticuloperitonitis

Bloat

Rumen Impaction

Ruminal Acidosis

Hypocalcemia

Vagal Indigestion

Stress/Fear

Drugs

21

What receptors does lack of eating affect to cause decrease in rumen motility

Decrease in buccal mechanoreceptor stimulation

Decrease reticulorumen tension receptor stimulation

Decrease epithelial receptor stimulation, decreases rumination

22

How does an LDA or RDA decrease rumen motility?

Abomasum distended with air or fluid

Stimulation of abomasal tension receptors

Incrases inhibitory inputs to gastric centre

All of this causes pain

23

What is hardware disease also known as?

Traumatic Reticuloperitonitis

24

How does traumatic reticuloperitonitis cause a decrease in rumen motility?

Direct depression of gastric center

- Pain

- Acute phase proteins (inflammation and fever)

- Lack of appetite

25

Two types of bloat?

Free gas bloat

Frothy bloat

26

Explain free gas bloat

Failure to eructate

Not an overproduction of gas

Typically due to something blocking esophagus

27

How does bloat decrease rumen motitily?

Increase inhibitory signals to gastric centers from epithelial receptors

28

What is frothy bloat

More common than free gas

Some legumes and alfalfa cause formation of froth 

- gas produced by bacteria remain trapped in solution

Froth covers cardia

Inhibits eructation reflex

29

Explain rumen impaction

Common in Sk

ingestion of large quantities of poor quality or indigestibel feed (ie straw)

Leads to rumen distension

30

How does rumen impaction decrease rumen motility

High rumen pressure, increases inhibitory signals to gastric center from epithelial receptors

31

Explain ruminal acidosis

CHO engorgement (grain overload)

More lactic acid produced, pH drops

 

32

How does Ruminal acidosis decrease rumen motility?

Increase inhibitory signals to gastric centre from epithelial chemoreceptors

33

Explain hypocalcemia (milk fever)

Common periparturient disease of dariy cows

Low plasma (extracellular) calcium

34

How does hypocalcema cause decreased rumen motility?

Failure of Neuromuscular transmission

- Impulse transmission down vagal nerve is depressed

- extracellular Ca needed for ACh release from axon into synaptic cleft

Rumen/Reticulum smooth muscle requires Ca for contraction

35

What occurs in downer cow?

Inappetant - decrease gastric sitmulation

Fluid covering cardia - decrease eructation

36

With respect to rumen motility, what is the vagus nerve responsible for?

Ruminoreticulum motility

37

What does a vagotomy do?

Stops motility, rumination and eructation

38

How does Stress/fear decrease rumen motility?

Increases sympathetic response

- Splanchnic nerve inhibits motiliyt

39

Affect of atropine on rumen motility?

Competitive ACh antagonist

- blocks parasympathetic transmission at post-synaptic receptors (vagal nerve)

40

Can drugs be used to treat rumen stasis?

No, dont treat for rumen immotility, find out what is causing the problem