ANFF topic 1 part 2

Question 1

What animals have a multi-chambered stomach?

Answer 1

• artiodactyla (cattle, deer, relatives)

- ruminants

Question 2

What kind of stomach do perissodactyla (horses, rhinos, tapirs) have?

Answer 2

• monogastric stomach

Question 3

How many chambers does the stomach of ruminants have?

Answer 3

• 4-chambered stomach

Question 4

Define rumination.

Answer 4

• repeated regurgitation of ingesta from reticulum

- re-mastication and re-swallowing

Question 5

When do cows regurgitate their food?

Answer 5

• during rest periods

- cows regurgitate soft feed wads to re-chew and break into smaller pieces

Question 6

What does regurgitation facilitate?

Answer 6

• the mechanical breakdown of tough plant material through multiple chewing cycles
• results in a greater surface area on which the digestive enzymes can act
• makes feed easier for the microbes to digest in the stomach

Question 7

What is the cow’s saliva rich in?

Answer 7

• bicarbonate

- do not have amylase

Question 8

What is the function of saliva in ruminants?

Answer 8

• buffers pH levels (between pH 6.2 to 6.8) in the reticulum and rumen
• moistens feed prior to fermentation
• provides liquid for microbes
• mature cow can produce up to 100-150 L of saliva per day

Question 9

What are the 4 chambers in a cow’s stomach?

Answer 9

• rumen (1st)
• reticulum (2nd)
• omasum (3rd)
• abomasum (4th)

Question 10

Which is the largest compartment of a cow’s stomach?

Answer 10

• rumen

- occupies 3/4 of the animal’s entire abdominal cavity

Question 11

What is the structure of the rumen like?

Answer 11

• numerous papillae in various shapes & sizes
• contains 130 L of rumen liquor
• hosts a population of microorganisms for fermentation

Question 12

What is the function of the rumen?

Answer 12

• allows soaking, physical mixing and breakdown of feed

Question 13

How is the rumen partitioned?

Answer 13

• based on their specific gravity of feed

Question 14

Where do lighter feed and heavy objects go to?

Answer 14

• lighter feed remains in the rumen (grass, hay)

- heavy objects fall into the reticulum (stones, grains)

Question 15

What flows through the rumen rapidly?

Answer 15

• water

Question 16

Why does water flow through the rumen rapidly?

Answer 16

• critical in flushing particulate matter downstream

Question 17

What percentage of ingesta is fermented by microbes before being exposed to gastric juices?

Answer 17

• 60-75%

Question 18

Where is the reticulum located?

Answer 18

• next to the heart

- very close to the rumen

Question 19

What is the structure of the reticulum like?

Answer 19

• honeycomb-shaped interior

Question 20

Are there any enzymes present in the reticulum?

Answer 20

• no

Question 21

What is the function of the reticulum?

Answer 21

• collects smaller particles and move them into the omasum
• heavy or dense feed and metal objects eaten by the cow drop into this compartment
• if metal objects ingested is not treated/removed, can result in “hardware disease”

Question 22

What separates the rumen and reticulum?

Answer 22

• separated by a muscular fold of tissue

Question 23

Reticulorumen

Answer 23

• rumen and reticulum considered as one organ
• makes up 84% of the total stomach volume
• ingesta flows freely between the reticulum and rumen

Question 24

Where are volatile fatty acids (VFAs) produced?

Answer 24

• rumen

Question 25

What do ruminal contractions result in?

Answer 25

• rumination

- constantly flush lighter solids back into the rumen

Question 26

What happens to the smaller and more dense digesta?

Answer 26

• pushed into the reticulum and into the omasum

Question 27

What is the pH of the rumen?

Answer 27

• pH 5.3 to 7.3

Question 28

Describe the structure of the omasum?

Answer 28

• spherical to crescent shape
• consists of multiple leaflets, known as omasal laminae
• covered with omasal papillae

Question 29

What does omasal laminae do?

Answer 29

• increase surface area

Question 30

What does omasal papillae do?

Answer 30

• increase friction against food particles

Question 31

What important role does the omasum play?

Answer 31

• transport of appropriately sized feed particles from the reticulorumen to the abomasum
• eosophageal groove closure (allows milk to go directly into the abomasum –> no fermentation)
• fermentation of ingesta
• absorption of water, volatile fatty acids and minerals

Question 32

What is the abomasum known as?

Answer 32

• the true stomach

Question 33

What is the function of the abomasum?

Answer 33

• functions similarly to the monogastric stomach

- digestion of proteins and fats

Question 34

What does abomasum contain?

Answer 34

• process glands –> secrete acids (HCl and digestive enzymes) for digestion
• microbial digestion
• contains lysozyme that breaks down bacterial cell wall

Question 35

What is eructation?

Answer 35

• belching

- removal of gas produced within the digestive tract (through the oesophagus or anus)

Question 36

Why do cows have so much gas?

Answer 36

• fermentation in the rumen generates 30-50 L per hour of gas in cow
• carbon dioxide and methane produced by the microbes

Question 37

What happens if an animal fails to eruct?

Answer 37

• result in ruminal tympany (bloatedness)
• ruminal tympany is life-threatening
• interferes with breathing
• results in suffocation