Lecture 31: Ruminant Digestive Physio 1 (Exam 3)

Question 1

What does the digestive strategy of all ruminants do

Answer 1

• Protection from predators
• Ingest enormous quantities of forage in short time thus min exposure in the open
• Spend max time ruminanting in the protection of trees

Question 2

What type of epithelium are found in the rumen, reticulum, & omasum

Answer 2

Stratified squamous

Question 3

Describe the stratified squamous epithelium found in the ruminant forestomachs

Answer 3

• No glands
• Pillars & papillae

Question 4

Describe the ruminant GIT

Answer 4

• Compartmentalized stomach in the order: rumen to reticulum to omasum to abomasum
• Pregastric fementation accomplished by microbes (protozoa, bacteria, & fungi)

Question 5

What do pseudoruminants not have

Answer 5

An omasum

Question 6

What are differences btw/ ruminants & non ruminant herbivores

Answer 6

• The site of fermentation
• Ruminants get energy from VFAs
• Horses get energy from starch digestion in the SI & some VFAs in the hindgut

Question 7

List some ruminant species

Answer 7

• Cattle
• Bison
• Sheep
• Goats
• Deet

Question 8

How do ruminants breakdown feed physically

Answer 8

• Prehension
• Mastication + eating
• Rumination (regurgitation + remastication)
• Microbial fermentation (bacteria, fungi, & protozoa)

Question 9

What are the nasolabial glands

Answer 9

• Present on the dermis of the muzzle
• Very watery to keep the whole nose & mouth moist

Question 10

What are the major salivary glands (produce majority of the saliva) in ruminants

Answer 10

• parotid
• Mandibular
• Sublingual

Question 11

What type of salivation does each major gland produce

Answer 11

• Parotid - serous (watery)
• Mandibular & sublingual - mixed

Question 12

What makes mucus salivation thick

Answer 12

Lipoproteins

Question 13

How much saliva do ruminants produce

Answer 13

~ 40 gallons

Question 14

What are the composition & functions saliva

Answer 14

• Made of: bicarb, urea, potassium, phosphate, & Cl
• Bicard is the most important for buffering the acid in the rumen
• Functions: buffering, add moisture to food (70% of all water in the rumen comes form saliva), & lipase

Question 15

What envi conditions are needed to support fermentation

Answer 15

• Have to have an appropriate substrate (Have to feed the microbes in the rumen)
• Temp around 37
• Osmo near 3000 mosm
• Anaerobic conditions
• Need frequent mixing of ingesta (rumen motility)
• Reducing particle size
• Removal of indigestible material removal (like the removal of lignin)
• Synchronized movement of ferment content to the intestine (depends on particle size; the smaller particles can leave)
• VFA must be buffered & removed/absorbed (pH of 6.8)

Question 16

What do microbes need to fxn

Answer 16

• Energy
• Nitrogen (from protein or urea)

Question 17

What are appropriate substrates

Answer 17

• Starch
• Cellulose
• Protein/nitrogen (urea)

Question 18

What is the primary site of fermentation

Answer 18

Rumen

Question 19

What is the #1 type of microbe present in the rumen

Answer 19

Bacteria

Question 20

What are cellulolytic bacterial species

Answer 20

Bacteria prefer action on grass

Question 21

What are Amylolytic bacterial species

Answer 21

Bacteria that prefer starch & sugar

Question 22

Describe the end products of fermentation in the rumen

Answer 22

• Acetate, propionate, & butyrate
• Provide energy to the animal
• Methane, CO2, & heat are by products of fermentation
• More acetate os produced overall on a fiber diet (grass); 65: 25: 10 ratio
• More propionate produced on a grain diet; 50: 40: 10

Question 23

What is this

Answer 23

Papillae

Question 24

Describe papillae found in the rumen

Answer 24

• Increase SA
• Vary in size
• Main fxn is to absorb VFAs (stabilize the rumen pH)
• Extremely impt in grain diets

Question 26

Describe the muscular pillar & fold in the rumen

Answer 26

* Help divide the rumen in to diff areas * Help w/ contraction by squeezing together * Primary contraction start in the reticulum & moves caudally * Contraction & mix -> relax -> repeat

Question 27

What is the appearance of the reticulum

Answer 27

Honey comb

Question 28

What are the 3 major functions of the reiculum

Answer 28

* Form bolus for regurgitation * Move particles to the omasum (small enough particles exit the rumen) * Move particles to rumen (larger particles)

Question 29

What is an important prob that is associated to the reticulum

Answer 29

Hardware disease (Bovine traumatic reticuloperitonitis)

Question 30

How does the material from the rumen passes into the omasum

Answer 30

Via the reticulo-omasal orifice

Question 31

What is this

Answer 31

Omasum

Question 32

Describe the omasum

Answer 32

* Material from the rumen passes into the omasum via the ritculo-omasal orific * "many piles" * Regulates passage of digesta into lower tract * Some absorption of water & VFAs

Question 33

Describe the abomasum

Answer 33

* Gastric stomach * Lots of folds * Lots of gastric glands that secrete HCL (acidity kills microbes washing them in from the rumen which provide proteins that are essential AAs) * Secretion of pepsinogen - hydrolyzes microbial & dietary protein

Question 35

Describe the abomasal contractions & their importance

Answer 35

* About 2 or 3 every min * Mixing * Material exits to the SI * Drives gas back to the rumen: CO2 dissolved in the rumen fluid liberated when it meets acid in the abomasum

Question 36

What does forage contain

Answer 36

* Cellulose * Hemicellulose * Sugars * Starch * Protein * Lignin

Question 37

What does concentrate (grain) diets contain

Answer 37

* Starch * Protein * Sugars

Question 39

What are the micro organisms doing to the substrate in the rumen

Answer 39

* Attach & grow on the substrate * Use metabolizes to grow & reproduce * Secrete metabolites

Question 40

List the layers of the rumen

Answer 40

* Bottom layer - small high density particles * liquid * Fiber mat - everything in this layer has large low density particles (provides "scratch factor") * Top layer - gases (near to the esophagus so they can be released)

Question 41

What products are undergoing fermentation in the rumen

Answer 41

* Monosaccharides * Diasccharides * Starch * Cellulose * Other sugars

Question 42

What are sugars fermented into

Answer 42

VFA

Question 43

What is starch being ferment to

Answer 43

Glucose then into VFA

Question 44

What is cellulose fermented into

Answer 44

Glucose -> VFA

Question 45

Is lignin fermented/digestable

Answer 45

NO

Question 46

Describe the blood glucose of ruminants

Answer 46

Lower blood glucose (60 mg/dl) compared to most non-ruminants (100 mg/dl)

Question 47

What is used in fat synthesis (milk & body fatO

Answer 47

Acetate is used

Question 48

What is the % of VFAs fermented from carbs

Answer 48

* 60% Acetate * 30% propionate * 10% butyrate

Question 49

What are proteins fermented to

Answer 49

* Peptides * AAs * Ammonia * Branched chain VFAs

Question 50

When do microbes use protein

Answer 50

Use the protein components & metabolites in synthesizing the cell wall & cytoplasmic proteins

Question 51

Where are dead microflora digest

Answer 51

The small intestine

Question 52

What type of protein do microbes provide

Answer 52

* The highest quality protein * Contain essential AAs the animal needs

Question 53

Can cattle be fed low quality proteins (Lack essential AAs) or metabolites (urea)

Answer 53

* Yes * Cows absorb the highest quality of AAs from the SI

Question 54

Where is urea produced

Answer 54

The liver

Question 55

T/F: There is minor urea recycling in ruminants

Answer 55

False: major urea recycling

Question 56

What happens after ammonia is produced in the rumen (from protein fermentation)

Answer 56

It is immediately utilized by microbes or absorbed & converted to urea by liver

Question 57

What are the fates of urea

Answer 57

* Excreted by the kidney * Recycled to the saliva * Recycled to the rumen

Question 58

What is the primary contraction of the rumen

Answer 58

* Major coordinated movements cranial to caudal for mixing * About 2 per min

Question 59

What are secondary contractions in the rumen

Answer 59

Caudal to cranial primarily to eructate gas

Question 60

What contractions are associated w/ cud chewing

Answer 60

Reticular contractions

Question 61

Describe regurgitation

Answer 61

* Initiated by a reticular contraction & relaxation of distal esophageal sphincter * Bolus enters the esophagus & goes to the mouth then is re chewed & ingested

Question 62

Describe rumination

Answer 62

* Reduces particle size, increases SA, & adds saliva * Regurgitation -> reinsalivation -> remastication -> reswallowing * Occurs when the animals is resting * Begins 30 to 90 mins after eating

Question 63

What initiates regurgitation

Answer 63

A reticular contraction & relaxation of distal esophageal sphincter

Question 64

What is the process of rumination

Answer 64

* Initiated by an "extra" contraction of reticulum that pushes ingesta into an area of the cardia * Distal esophageal sphincter opens * inspiratory excursions w/ glottis closed causing neg pressure in intrathoracis esophagus * bolus of ingest moves into the esophagus

Question 65

What is the process of reinsalivation, remastication, & reswallowing

Answer 65

* Reverse peristalsis "vomits" bolus into the mouth * Fluid are squeezed out of the bolus & swallowed * Ingesta is chewed & additional saliva is added * Cud is swallowed & the process is repreating * Mediated by the medulla * Epithelial receptors in the reticulum for the "scratch factor"