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Veterinary medicine year 2 > Ruminant GIT > Flashcards

Ruminant GIT Flashcards

Covers cards for all of the rumen and a little bit on the monogastric stomach

1
Q

What are ruminal papillae affected by?

A

The concentration of VFAs

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2
Q

How will high VFA diets affect the papillae of a ruminant?

A

High VFA= long luxuriant VFA

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3
Q

What volatile fatty acids are produces in the ruminant?

A

Acetic acid
Butyric acid
Propionic acid

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4
Q

What is the precurser of propionic acid?

A

Propionate

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5
Q

What is the major product of nutrient digestion?

A

pyruvate
pyruvate is converted to VFAs for microbiota

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6
Q

Describe the absorption in the forestomach

A

Water flows in and out based on osmolarity
AT of Na maintains electro gradient
VFA absorbed and transported to liver
Ions reabsorbed and recycled

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7
Q

Where are VFAs absorbed?

A

Through rumen wall and some through omasum

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8
Q

Why is cellulose difficult to digest?

A

Low surface area to vol ratio
Ruminants do not have enzymes to break down cellulose

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9
Q

How can ruminats break down cellulose?

A

Cudding -Chewing food and regurgitating and reswallowing
Musc contraction of the rumen affects SA:V ratio and inc microbial fermentation

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10
Q

What is the reticuloomasal orifice?

A

Sphincteral structure which forms the connection between the reticulum and the omasum
Ingest must pass through before reaching distal digestive tract

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11
Q

How can ruminants get the enzymes to break down cellulose?

A

Microbiome bacteria have the correct enzymes
Bacteria digest cellulose and release VFAs

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12
Q

What are the functions of the rumen microbiome?

A

Bacteria w diff enzymes
Bacteria act on diff substrates so produce different products = food web

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13
Q

What is the diet of the rumen microbiome?

A

Cellulose
Lignin
Starch
Oil
Protein

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14
Q

Why is the rumen microbiome a symbiotic relationship?

A

Bacteria = protection and nutrients
Rumen = VFAs in return

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15
Q

How is an anaerobic environment maintained in the rumen?

A

O2 entering is soaked up by bacteria to maintain conditions
Involves methanogens in terminal stages of degradation organic material in An conditions

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16
Q

What is the function of microbial fermentation?

A

High quality feed from poor
adds nitrogen from non protein nitrogen sources
Incorporates carbon into microbial proteins and nucleic acids
Provides essential AA

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17
Q

How is fibre digested in the rumen?

A

Broken down by protozoa in the microbiome

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18
Q

How do anaerobic fungi help break down fibre?

A

Enzymatic breakdown using hemicellulose, cellulases, xylanases, glycosidases
Increase surface area

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19
Q

What are archaea?

A

A group of microorganisms similar to but evolutionarily distinct from bacteria
Extremophiles

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20
Q

Role of Archaea in rumen?

A

Range of diff metabolisms including methanogenesis
This uses H and Co2
Good bc H needs to be removed from rumen for conditions

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21
Q

What is involved in the rumen examination?

A

Position examination
Abdominal silhouette
Faecal examination
Rumen fill scores

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22
Q

What is the reticulum?

A

Crescent shaped struct w smooth contour that collects smaller digesta and moves them to the omasum while larger particles remain in the rumen

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23
Q

What is the internal structure of the reticulum?

A

Tissues in the reticulum form a network similar to a honeycomb

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24
Q

Where is the reticulum in relation to the rumen?

A

Adjacent to the diaphragm, lungs abomasum, rumen and the liver

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25
What is the ruminoreticulum?
Small tissue fold between the reticulum and the rumen (the two arent separate compartements)
26
How do ruminants regurgitate ingesta?
initiated w a reticular contraction distinct from primary contraction Contraction in conjunction with the relaxation of the distal oesophageal sphincter allows a bolus to enter oes
27
What are the two kinds of ruminal contractions
Primary - mixing Secondary - eructation
28
Describe primary ruminal contractions
Originate in the reticulum and pass caudally around rumen Wave contraction followed by a wave relaxation
29
Describe secondary contractions
Only occurs in some parts of the rumen
30
What is the 3rd contraction of the rumen?
Facilitates remastication
31
Describe the primary rumen motility pattern
Initiation of cycle by a double reticular contraction 1st ret contraction 2nd- ret contraction evacuates particles through ROO Cont of cranial retrum fold moves material in dorsal sac followed by vent sac Ventral sac cont moves dense material to the reticulum
32
Describe the second rumen motility pattern
Dorsal sac contr cranially to caudally moving gas cap forward ret and Reticuloruminat fold reflex Exposed cardia opens and gas enters oes Ventral sac contracts caudal to cranial and retrum fold relaxes Dense material moves forward into the sac
33
Describe the nervous control over ruminal motility
Rich ENS system Coordinated contractions from cns in brainstem via vagal efferent nerve Vagal efferent nerves from rumen to motility centres allows stretch receptors and chemoreceptors to modulate contractility
34
Rumen contraction timings
3 rumen contractions every 2 mins
35
How does ruminal motility affect the food?
Food sits in layers rumen shakes form side to side so separates food into density layers
36
What is the importance of forestomach motility?
Continous mixing of bacteria and food Retains ingesta for microbial digestion and down sizing of particles Appropriate env by removing gas
37
Describe the location of the abomasum
Located in the ventral abdomen to the right of the midline in the cranial abdomen in the sheep
38
What is a displaced abomasum?
movement of abo out of normal position L: Caught between rumen and left abd wall R: Abomasum moves up right wall and is trapped above the omasum
39
What are the effects of an LDA?
Stretching = constriction of exit from abomasum = gas therefore a ping is heard at rib 9-13 on left
40
What is the effect of an RDA?
Constricts outflow from the abomasum= gas Twists all the way over = colic
41
How does the omasum and abomasum work together?
Omasum = pump the aspirates ingesta and transfers to the abomasum
42
What is the structure of the abomasum?
Fundus, body pylorus Longitudinal rugae Columnar epithelium glands no pyloric sphincter - wall thickening instead
43
What is the normal pH of the abomasum?
3.4
44
What are the stomachs of the ruminant and their functions?
Rumen - fermentation vat Reticulum - part of the rumen Omasum - Water absorption Abomasum- true stomach
45
Describe the anatomical location of the rumen
Located on the left - moves all viscera to the right Liver is at 6-12 o clock rotation
46
What lines the rumen?
keratinised epithelium ( has own blood supply so is able to absorb nutrients and water)
47
What is the structure of the ruminal papillae?
Leaf shaped Keratinised Poorly developed in the roof of the dorsal sac Absorb VFAs
48
What lines the reticulum?
Series of keratinised cells with smaller cells inside Have conical papillae
49
How will feed quality affect the time spent in the rumen?
Poorer = longer in rumen Rough hay = more time in rumen Ruminants are supposed to be slow digesters
50
Describe the structure of the omasum?
Broadly spherical with flattened sides COntains lost os laminae which are covered with conical papillae Laminae in 3 size groups
51
Describe the motility of the omasum
regular biphasic contractions squuze materials into the rececesses General contraction pushes fluid forward
52
What are the major omasal anatomical structures?
Omasal canal Reticuloomasal orific Omasal abomasal orifice Omasal leaves
53
How is milk digested in the ruminant neonate?
Digested in the abomasum Fundus glands = rennin = coagulates casein in acid env Clot retains milk to allow complete digestion by pepsin
54
What is the reticular groove in the ruminant?
In neonates Acts as a diversion for milk
55
What is the reticular groove reflex?
Stim by vagus nerve - ~Groove contracts to create a tunnel between the oes and the reticuloomasal orifice
56
How does the size of the chambers change as the neonate grows?
Abo is larger in young Growth of the reticulorumen and omasum = more roughage = fermentation
57
What are the oligosaccharides?
Disaccharides Sucrose Lactose Maltose Cellbiose
58
What is the function of glucan?
Storage and structure (starch, glycogen, cellulose)
59
What is dextrin?
Glucan that is the intermediate in the hydrolysis of starch and glycogen
60
What are the different types of glycans?
Heteroglycan = high molecular weight mix of sugars (hemicellulose) Homoglycans= high molecular weight by no sugar reactions
61
How is fat digested in the rumen?
Rumen hydrolyses fat = mored saturated Occurs mainly in the abomasum
62
Why should calcium fatty acids be administered when giving ruminants high fat content?
§Fat depresses the microbial activity Long chain fatty acids cannot be absorbed in the rumen
63
How is undegradable protein digested?
Not in the rumen Travels to the abomasum and small intestine
64
How is degradable protein digested?
Protein -> peptides -> amino acids -> ammonia Ammonia is either excreted by liver or used to make microbial proteins from urea Urea is used in the salivary glands
65
Why does good quality protein need to be protected?
Should be protected by lipid micelles or needs to be undegradable Rumen makes poor quality protein or non nitroprotein better
66
How does the rumen digest non nitrogen protein better?
non protein nitrogen is made better as microbiome uses ammonia so this can be used to create VFAs
67
Microbial crude protein synthesis is dependent on?
Protein and energy protein > energy = energy limiting inc ammonia energy > protein = limited by protein energy lost as methane
68
What changes can affect the rumen?
Acidosis and alkalosis Diurnal feed changes between batch Starvation Antibiotic therapy
69
What are the clinical signs of chronic acidosis?
Caused by a diet that is too high in concentrate - Suboptimal rumen function - Reduced food intake - Pain - indigestion - loose faeces - low milk fat levels
70
When is the acid buffering capacity of the rumen overwhelmed?
pH 6
71
Compare cranial and caudal fermenters
cranial- large vat between oes and true stomach w microbiome. Can use protein from fermentative microbes Caudal- Fermentation in the large intestinwe Both extract from cellulose- Both can utilise dietary hexose directly
72
Outline the GIT of camelids
3 oesophageal diverticulums (C1(cran and caud), C2 and C3) C1- 80% of gastric vol, homo ingesta C2- liquid ingesta C3 - elongated gastric glands and true stomach Specialised saccules in C1 for VFA abso ( thin walled invaginations)
73
What factors allow continuous fermentation?
Rumen temp Filling and emptying VFA absorption Eructation 8 hr ruminating = saliva input and output close together Large surface area
74
What is the role of ruminant saliva?
Acidifying effects of VFA buffered by bicarbonate and phosphate in large volumes of saliva
75
How is the rumen able to be a continuous culture system?
Complex polysaccharides each Microbial fermentation = VFA, gases VFA absorbed Eructation of gases Partially digested food-> abomasum
76
What is the role of the keratinised epiuthelium?
Protective absorptive function non glandular Found in the rumen, reticulum and omasum
77
What can be seen histologically in the reticulum?
Mucosa- series of cells w smaller cells inside, no conical papillae,keratinised Reticular crest Muscularis mucosa Lamina propria (submucosa) Reticular papillae
78
Protozoa within the ruminant?
Single celled eukaryotes Not sure on the role 100 species
79
Fungi within the rumen?
Strict anaerobes Colonise plant fragments actively ferment cellulose and soluble sugars = acetate, lactate, ethanol and succinate Fibre digestion
80
What is the main bacterial pathogen in the monogastric stomach?
helicobacter pyori
81
What is the action of helicobacter pylori?
1. Into mucous layer and binds to membrane associated lipids of epithelium 2. secretes lots of urease which neutralises => ammonia 3. ammonia = neutral gastric acid 4. Ammonia is toxic to epithelial cells 5. Helicobacter can survive in higher pH 6. Helicobacter releases protease, catalase and phospholipase = damages epithelial cells
82
Properties of helicobacter pylori
Helical shape Gram negative gastric mucosa of dogs and cats Can be determined w faecal PCR, urea breath, blood test of serology
83
What factors affect protection of the monogastric stomach?
Age = pH Neonates= overgrowth Food type affects barrier function Pharmacology
84
What is assessed in ruminocentises?
Colour Smell pH - 6.7 norm Bacterial viability Protozoa Sedimentation
85
How to carry out ruminocentesi?
5 ml anaesthetic 5 mins Clean left side 2-10cm caudal to last rib and level w stiff 16 gauge 4 inch 20 ml syringe Aspirate fluid
86
What agents cause Johnes?
- Mycobacterium avium subspecies paratuberculosis - Gram-positive bacteria - aerobic and slow growing - acid-fast due to thick waxy wall - can survive pasteurisation - Obligate intracellular bacteria
87
How is MAP spread with Johnes?
Faeco orally
88
Johnes- How does MAP enter the host?
MAP=> SI => macrophages and lives in them Early on it is contained bc slow growing Some macrophages have apoptosis so MAP is released in the intestines Th1 cells detect through interferrin gamma MAP contain within GIT and GALT but not killed Th1 cells stimulated Lymphocytes and macrophages => submucosa
89
Compare the action of Th1 and Th2 in johnes?
Th1 = cytokines IFNy with macrophage dominance Th2= Cytokines IL-4, IL-10 and antibody production
90
What are the stages of johnes?
Slow proliferation: of MAP in macrophages and in submucosa ( no antibody response, low shedding) Increase in MAP conc in submucosal, Granulomatous inflammation: and shedding of MAP Inflammatory response: blunts villus cells of SI Th1-> Th2 = antibody response V high antibody levels: and MAP shedding in faeces

Veterinary medicine year 2 (23 decks)

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