rumen anatomy

Question 1

what are the compartments of the tuminant stomachs and what do they do

Answer 1

• rumen = fermentation vat
• reticulum = part of rumen
• omasum = water absorption
• abomasum = true stomach

Question 2

what allows ruminants to digest digestable neutral detergent fibres

Answer 2

the rumen-reticulum and the omasum allows time and space for microorganisms to digest cellulose and hemicellulose (DNDF) because they produce the enzyme cellulase

Question 3

explain the process of foregut fermentation

Answer 3

digest cellulose and hemicellulose into volatile fatty acids by organisms in gut. volatile fatty acids are then quickly absorbed by stomach wall

Question 4

the rumen is one which side of the animal

Answer 4

left side

Question 5

discuss how the development of the papillae in the rumen is related to diet

Answer 5

• growth of papillae is stimulated by high concentration of volatile fatty acids and long fibres
• longest papillae will be in the top layer of rumen fluid where the long fibres float
• shortest at top of rumen where gas cap sits
• take time to adapt but can change when diet changes

Question 6

discuss rumen papillae form and function

Answer 6

• leaf shaped
• keratinized
• poorly developed in roof of dorsal sac
• increased surface area for flora absorption

Question 7

what is the prupose of reticuloruminal contractions and how many are normal within a 2 minute window

Answer 7

• stirs, redistributes and mechanically grinds fibres
• partitions fibre for re chewing

3 every 2 minutes is normal

Question 8

what is the pH of them reticulorumen

Answer 8

about 6.5 to allow microorganisms to digest and degrade plant material (cellulose and hemicellulose)

Question 9

fermentation of plant material results in which compounds being made

Answer 9

• fatty acids: acetate, butyrate and propionate)
• carbon dioxide
• methane

Question 10

what compartment is this from

Answer 10

reticulum

Question 11

why are grains sometimes troublesome for ruminants

Answer 11

• grains spend less time in the rumen
• as they are broken down they release acid into rumen and upset pH balance
• especially for dairy cows when they are fed a high concentrate feed after calving, leading to ruminal acidosis and increased gas in abomassum (motility issues leading to LDA/RDA
• provide more energy byt can lead to greater problems
• if ingesting large amounts of grain rapidly, produce lots of gas = bloat

Question 12

how does food matter get from the reticulorumen to the omasum

Answer 12

reticulo-omasal orifice

Question 13

the omasum is characterised by its

Answer 13

~100 lmainae covered in conical papillae which point in the direction of flow

Question 14

which species interesting does not have an omasum

Answer 14

camels (tylopods)

Question 15

what are the species differences of the abomassum

Answer 15

• relatively larger in sheep and goats
• sits more vertically in sheep and goats
• larger contact with abdominal floor in cattle

Question 16

explain how the neonatal ruminant diegests milk without fermenting it

Answer 16

• digested in the abomasum
• fundic glands produce renin which coagulates casein (milk protein) in acidic environments
• the clot retains milk to allow complete digestion by pepsin
• reticular groove acts as diversion for milk so it desnt go into rumen

Question 17

explain how the reticular groove works for ruminant neonates

Answer 17

• if milk goes into rumen, it will ferment leading to scour
• when reticular groove is relaxed, esophagus empties into reticulum/rumen
• when contracted edges of the groove curl up and create a tunnel between the esophagus and the reticulo-omasal orifice
• stimulated to contract by reticular groove reflex

Question 18

how does the reticular groove reflex work

Answer 18

• when stimulated by the vagus nerve, the groove contracts to form a closed tube
• stimulated by suckling/pharyngeal stimulation and noises associated with meal time
• reflex poorly reactive to drinking and stomach tubing (why you shouldnt bucket feed calves because they dont get stimulation by suckling)
• reflex does still work in adults but only in cases of dehydration (mediated by ADH) and drenches

Question 19

explain how the young calf is able to transition from milk to solid feed during weaning

Answer 19

• after birth the forestomach starts to develop and grow
• deelopment is promoted by the presence of forage in the rumen as the young animal starts to pick at solid food
• a rumen flora develops within a couple weeks of birth
• functional by 6-8 weeks
• by the time animals are weaned, forestomach is capable of digesting an adult diet