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GI > Week 2- 2/3 - Rumen - complete *** > Flashcards

Week 2- 2/3 - Rumen - complete *** Flashcards

1
Q

State the names of the chambers of the ruminant stomach in the order they are encountered in

A

reticulum
rumen
omasum
abomasum

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2
Q

On the gross animal, where is the rumen located?

A

it spans the entire left hand side of the ruminant

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3
Q

Describe the structural features of the Oesophagus 3

A

striated muscle along its length
the mucosa is insensitive
it is heavily keratinised

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4
Q

What is the overall capacity of the ruminant stomach?

A

100-250 litres

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5
Q

What name is given to the rumen and reticulum as a single functional unit?
- What conditions are present in the rumen? 4

A

the reticula-rumen

anaerobic conditions
ph of 6.5
moist
temperature 38-42 degrees

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6
Q

How do ruminants increase the surface area of long fibrous feedstuffs? 2

A

initial mastication
rumination

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7
Q

How often does the reticule-rumen contract?
- What is the purpose of each contraction? 2

A

3 times every 2 minutes

to stir, redistribute and mechanically grind ingesta
to partition fibre for re-chewing

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8
Q

Papillae: What stimulates the growth of Papillae? 2
- Hence, where are they longest and why?
- Where are they shortest and why?

A

a high concentration of volatile fatty acids
long fibre

at the top of the fluid layer where the long fibres float

at the top of the rumen where the gas cap sits

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8
Q

Reticulum: Describe the structure of the reticulum 4

A

it is a series of cells
with small conical papillae
keratinised
hexagonal appearance

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8
Q

Describe the appearance of the Papillae of the rumen 2
- What is their function?
- Are they all the same size?

A

keratinised
leaf shaped

to increase the surface area in the rumen for fermentation by flora and reabsorption

no they vary in size and shape based on diet and location

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9
Q

How does ingesta flow from the reticulum into the omasum?

A

via the reticulo-omasal orifice

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10
Q

Omasum: What is the function of the Omasum? 3

A

water absorption
volatile fatty acid absorption
pumping of ingesta form reticulum to abomasum

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11
Q

Omasum: How many Laminae does it contain?
- What is present on the surface of Laminae and what is the purpose of this?
- How many distinct groups do laminae form?

A

100

conical papillae to increase the surface area

3

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11
Q

Abomasum: What is the abomasum generally termed?
- What sections can it be divided into?
- In which species is it relatively larger?

A

the true stomach

the fundus, body and pylorus

sheep and goats

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12
Q

Abomasum: How many rugae does it contain?
- How do these rugae differ from other domestic species?

A

12 large longitudinal rugae

they are permanent even when distended

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12
Q

Abomasum: How is the position of the abomasum in cattle different to sheep and goats?

A

the abomasum has increased contact with the abdominal floor in cattle

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13
Q

Abomasum: What is the PH here?
- Describe the contractions
- Describe the pyloric sphincter

A

3-4

weak and rhythmical

there is no pyloric sphincter, only a wall thickening that acts like a valve

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14
Q

Neonates: Where is milk digested?
- Describe how milk is digested 4

A

in the abomasum

fundic glands secrete renin
this coagulates the casein in milk in the acidic environment
the clots formed retain the milk allowing complete complete digestion by pepsin

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15
Q

Neonates: Why is it important that milk goes into the Abomasum and not the Rumen?

A

if it enters the rumen it will ferment and cause scour

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16
Q

Neonates: How does milk bypass the rumen?
- Describe what happens when his structure is relaxed
- Describe what happens when this structure is contracted

A

the reticular groove

the oesophagus empties into the reticulo-rumen

the edges of the groove curl up and form a tunnel between the oesophagus and the reticulo-omasal orifice

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17
Q

Neonates: What is the reticular groove reflex stimulated by? 2
- Wha nerve stimulates it?
- What is it poorly reactive to? 2

A

suckling milk
noises associated with the feeding routine

the vagus nerve

drinking
stomach tubing

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18
Q

When does the reticular groove reflex work in adults?
- When specifically in sheep?
- When specifically in cattle?

A

when dehydrated via ADH

drenches containing copper

drenches containing sodium salts

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19
Q

Weaning: What prompts the development of the rumen in young animals?
- How long after birth is the rumen functional?

A

the presence of forage in the rumen

6-8 weeks

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20
Q

Why do ruminants require microbial fermentation prior to normal digestion? 3

A

because the food they consume consists of many beta linked polysaccharides
they lack the enzyme required to break these bonds to access the nutrients
so require microbial fermentation as some microbes secrete this enzyme

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21
Describe what happens when ingesta enters the reticulum from the oesophagus 2
the ingesta enters the reticulum it mixes with rumen fluid and is prepared for the anaerobic conditions of the rumen
22
How is the ingesta prepared, in the reticulum, for the anaerobic conditions in the rumen? 2
the reticulum contains bacteria which respire any oxygen swallowed with the ingesta after utilising the oxygen they switch receptors and respire anaerobically
23
What can the rumen be thought of as?
a large fermentation vat
24
What happens to the microflora if you change the PH of the rumen? - What happens if ingesta moves through the rumen too quickly? - What are the consequences of disrupting the conditions in the rumen?
some of the organisms will die and be washed out some of the organisms will be washed out you many lose organisms leasing to poor rumen health and poor digestibility and poor animal health
25
Why are the conditions in the rumen strictly anaerobic?
because oxygen is toxic to many of the microbes in the rumen
26
What factors need to be maintained in order to maintain a stable microbial population in the rumen? 4
nutrients - there needs to be a consistent input of food PH needs to be maintained at 5.5-6.5 temperature needs to be maintained at 38-42 degrees redox - oxygen entering with food needs to be rapidly utilised to maintain anaerobic conditions
27
Microflora: How do different organisms differ from each other? - How do they form a food web? - What does this enable?
different organisms are better at metabolising different substrates and produce different products the products produced by one organism may be the substrate for another organism it enables fatty acids to reduce and reduce in the number of carbons until methane and co2 are produced
28
PH buffering: How is the PH in the rumen buffered? 2
VFAs and ammonia are rapidly absorbed through the rumen wall bicarbonate and phosphate are secreted in large volumes in saliva
29
Give 2 examples of other things synthesised by rumen microbiota that benefits the animal
vitamin b12 aromatic growth factors
29
PH buffering: How is saliva production stimulated? - Hence, which food types produce more saliva, and are therefore more easily buffered? - Which food types produce less saliva and why?
by mastication and rumination long fibrous feeds concentrate feeds because they require less chewing
30
Protozoa: Describe them - Which 2 families do most rumen protozoa belong to?
they are single cell eukaryotes holotriches oliogotriches
31
What happens when you change the diet of a ruminant? 2 - how long does this adjustment take? - What is the problem with making sudden dietary changes?
the microbiota will adjust the balance of organisms will change up to 2 weeks it can affect rumen function
32
Fungi: Describe their metabolism - How do they break down ingesta in the rumen? 3
anaerobes they colonise plant fragments then generate hyphae which extend into the material they release enzymes to break down the material
33
State 3 ways the rumen can be disrupted
acidosis starvation oral antibiotic therapy
34
Monogastric Stomach: What is the immunological function of the stomach? - Why is there minimal microbiology in the stomach? - Give an example of how some pathogens can affect the barrier function of the stomach - How can the barrier function be compromised pharmacologically?
to act as a barrier to infection of the lower intestinal tract because most bacteria is killed by the acidic PH pathogens hiding in meat the use of antacids
35
Monogastric Stomach: How can Antacids be a problem for the barrier function of the stomach? 3
they increase the PH of the stomach so the PH may not be acidic enough to kill the pathogen this can lower the infective dose of many organisms to just one
36
Monogastric Stomach: State the name of one organism of particular interest. - Describe its structure 3
helicobacter gram negative twisted rod shape flagellum
37
Monogastric Stomach: How does Helicobacter survive in the acidic stomach if it is not tolerant to such a low PH? 2 - From where does the bacteria obtain nutrients? - what consequence does this have to the stomach? - How is the damage further exacerbated?
it secretes urease which breaks down urea to ammonia ammonia is alkaline and neutralises the gastric acid from the tissues of the stomach wall it causes damage to stomach tissues ammonia is toxic to epithelial cells
38
Monogastric Stomach: How could you test for Helicobacter? 2
blood antibody test stool antigen test
39
Carbohydrates: State examples of monosaccharides 2 - State examples of disaccharides 3
hexose and pentose sugars sucrose, maltose, cellobiose
40
Carbohydrates: How can ruminants digest cellobiose?
the rumen contains bacteria which produces an enzyme to break it down and obtain the sugar
41
Carbohydrates: What type of molecule is cellulose? 2 - What does it contain? - Give examples of other Homoglycans of the storage polymer kind 2
a homoglycan structural polymer repeating units of cellobiose starch and glycogen
42
Carbohydrates: Give an example of a Heteroglycan. - What makes it a Heteroglycan instead of a Homoglycan? - Where is this Heteroglycan found in large amounts?
hemicellulose it is composed of several different sugars in grass
43
Carbohydrates: What are carbohydrates fermented to in the rumen? - Give 3 examples of these - What biproducts are formed from this microbial fermentation? 2
volatile fatty acids acetic acid, butyric acid, propionic acid methane and carbon dioxide
43
Carbohydrates: The carbohydrate enters the rumen. - What is it initially broken down into? - From this, what is it broken down into? - For which volatile fatty acid are there 2 different pathways from pyruvate?
pyruvate volatile fatty acids propionic acid
44
Carbohydrates: Propionic acid - When is pyruvate broken down into propionic acid down the most common pathway? - What types of foods encourage this pathway? - What is the alternative pathway called? - When is the alternative pathway used? 2
at a normal ph forage the lactic acid pathway very low ph during rapid digestion
45
Carbohydrates: When is a low PH created in the rumen? - Why is this? 4
when large quantities of readily accessible carbohydrates are consumed, often in high concentrate diets the carbohydrate can be quickly converted into pyruvate and then volatile fatty acids this causes the PH in the rumen to drop rapidly as it cannot absorb the volatile fatty acids quick enough to buffer this and at a low ph the lactic acid pathway for propionic acid is more likely to be utilised, further lowering the PH as lactic acid is very strong concentrates are less fibrous so require less chewing so less saliva containing bicarbonate and phosphate is produced to buffer the ph
46
Carbohydrates: What happens to the proportions of different VFAs produced as percentage concentrate increases?
the proportion of acetic acid decreases the proportion of propionic acid increases
47
Carbohydrates: Which forages increase the amount of acetic acid produced and why? - Which forages are more likely to be fermented down the propionic route and why?
older forages as they contain more cellulose and hemicellulose younger grasses because they contain a lot more sugars
48
Carbohydrates: How is the fore stomach adapted for VFA absorption? - Once absorbed, where are VFAs transported?
papillae and laminae increase the surface area of the fore stomach to the liver
49
Fat: What tends to happen to fats in the rumen? 2 - What is the problem with a high fat diet? - How can we get around this in order to increase dietary fats without compromising rumen function?
they are hydrolysed their structure is altered to become more saturated it will depress microbial activity calcium fatty acid salts do not depress microbial activity and can therefore be given as fat supplements
50
Protein: State the 2 types of protein - What happens to rumen undegradable protein?
rumen undegradable protein rumen degradable protein it passes through the rumen and is digested in the abomasum
51
Protein: What happens to Rumen Degradable protein in the rumen? 2
it will be broken down by organisms into amino acids some amino acids will be further broken down to form ammonia
52
Protein: What happens to some of the Ammonia produced in the rumen? 6
it is absorbed through the wall of the rumen it is transported to the liver where it is converted into urea some urea will be excreted in urine some urea will remain in circulation some circulating urea will be incorporated into saliva and recycled into dietary intake urea is converted in ammonia in the rumen
52
Protein: What can amino acids and ammonia be used for? - What does this require?
making microbial crude protein energy
53
Protein: Give an example of a Non-protein nitrogen that can be fed to ruminants to be made into microbial crude protein - What must the feed containing this non-protein nitrogen also contain and why? 3
urea lots of fermentable metabolic energy so that the ammonia made from the urea can be used to make the non-microbial proteins if there is not enough energy available, the blood concentration of ammonia will increase this could overwhelm the liver and create toxic circulating levels
54
The rumen is continuously fermenting. What is required to enable this system to continue fermenting? 4
a stable PH of 6.5 removal of gases formed a way in and a way out maintenance of a temperature of 38-42 degrees
55
How are gases removed from the rumen? - Which gases are produced? - How much of these gases can be produced after a large meal?
by eructation methane and carbon dioxide 30l
56
Synchronicity: What 2 things does Microbial crude protein synthesis depend on? - What happens if more protein is present than energy? - What happen is more energy is present than protein?
the presence of protein and energy the amount of microbial crude protein produced is limited by energy so ammonia concentration increases and the blood concentration of urea increases the amount of microbial crude protein produced is limited by protein and the excess energy is broken down to methane and wasted
57
Synchronicity: Why is synchronicity important for optimal rumen function? 3
the correct balance of energy and protein in the diet enables the establishment of the optimal microbial population this leads to optimum rumen function and optimal production of microbial crude proteins
58
PH: As discussed, high concentrate diets can lower the ph of the rumen, increase the proportion of Propionic acid produced and lactic acid. - Clinically, which 2 conditions can this cause?
acute acidosis chronic acidosis
59
PH: Why is it important to keep the PH in the rumen above 6?
because a PH below 6 is too acidic for cellulose digestion
60
Acute Acidosis: What usually causes this? - What clinical signs could be seen? 4
grain engorgement signs of GI pain, lying down, uncomfortable, belly kicking
61
Chronic Acidosis: Which group of animals is more susceptible to this? - What clinical signs would you expect to see? 3 - Why might production decrease? - Why might milk fat decrease?
high producing animals fed a high concentrate diet signs of GI pain, indigestion, loose faeces because appetite decreases, so food intake decreases, so dry matter intake decreases because we are not getting adequate volatile fatty acid production
62
Chronic Acidosis: What happens to the microflora when the PH falls? 3
the balance of rumen microflora changes the number of viable microorganisms decreases so the rate of digestion decreases
63
Bloat: When does bloat occur? 4 - What is the usual mechanism of death?
when gases are not removed from the rumen by eructation so the gases accumulate in the rumen this increases the size of the rumen which applies pressure to surrounding structures including the lungs suffocation
64
Bloat: What are the 2 types?
gas bloat frothy bloat
65
Gas Bloat: Why does this occur? - Give an examples of when this might occur 3
when something is blocking or hindering normal eructation physical obstruction of the oesophagus like a potato cessation of normal rumination due to rumen acidosis or vagal indigestion gas is unable to reach the oesophagus when in lateral recumbency
66
Frothy Bloat: When does this occur? - Why does this cause frothy bloat? 2
when the ruminant grazes pastures rich in clover soluble proteins in the clover leaves form a gassy foam with rumen gases gassy foam cannot be removed form the rumen by eructation so builds up
67
Bloat: How can you treat bloat?
by placing a cannula in the paralumbar fossa to release the gas and relieve the pressure

GI (6 decks)

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