ANFF topic 1 part 2 Flashcards
What animals have a multi-chambered stomach?
- artiodactyla (cattle, deer, relatives)
- ruminants
What kind of stomach do perissodactyla (horses, rhinos, tapirs) have?
- monogastric stomach
How many chambers does the stomach of ruminants have?
- 4-chambered stomach
Define rumination.
- repeated regurgitation of ingesta from reticulum
- re-mastication and re-swallowing
When do cows regurgitate their food?
- during rest periods
- cows regurgitate soft feed wads to re-chew and break into smaller pieces
What does regurgitation facilitate?
- 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
What is the cow’s saliva rich in?
- bicarbonate
- do not have amylase
What is the function of saliva in ruminants?
- 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
What are the 4 chambers in a cow’s stomach?
- rumen (1st)
- reticulum (2nd)
- omasum (3rd)
- abomasum (4th)
Which is the largest compartment of a cow’s stomach?
- rumen
- occupies 3/4 of the animal’s entire abdominal cavity
What is the structure of the rumen like?
- numerous papillae in various shapes & sizes
- contains 130 L of rumen liquor
- hosts a population of microorganisms for fermentation
What is the function of the rumen?
- allows soaking, physical mixing and breakdown of feed
How is the rumen partitioned?
- based on their specific gravity of feed
Where do lighter feed and heavy objects go to?
- lighter feed remains in the rumen (grass, hay)
- heavy objects fall into the reticulum (stones, grains)
What flows through the rumen rapidly?
- water
Why does water flow through the rumen rapidly?
- critical in flushing particulate matter downstream
What percentage of ingesta is fermented by microbes before being exposed to gastric juices?
- 60-75%
Where is the reticulum located?
- next to the heart
- very close to the rumen
What is the structure of the reticulum like?
- honeycomb-shaped interior
Are there any enzymes present in the reticulum?
- no
What is the function of the reticulum?
- 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”
What separates the rumen and reticulum?
- separated by a muscular fold of tissue
Reticulorumen
- rumen and reticulum considered as one organ
- makes up 84% of the total stomach volume
- ingesta flows freely between the reticulum and rumen
Where are volatile fatty acids (VFAs) produced?
- rumen
What do ruminal contractions result in?
- rumination
- constantly flush lighter solids back into the rumen
What happens to the smaller and more dense digesta?
- pushed into the reticulum and into the omasum
What is the pH of the rumen?
- pH 5.3 to 7.3
Describe the structure of the omasum?
- spherical to crescent shape
- consists of multiple leaflets, known as omasal laminae
- covered with omasal papillae
What does omasal laminae do?
- increase surface area
What does omasal papillae do?
- increase friction against food particles
What important role does the omasum play?
- 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
What is the abomasum known as?
- the true stomach
What is the function of the abomasum?
- functions similarly to the monogastric stomach
- digestion of proteins and fats
What does abomasum contain?
- process glands –> secrete acids (HCl and digestive enzymes) for digestion
- microbial digestion
- contains lysozyme that breaks down bacterial cell wall
What is eructation?
- belching
- removal of gas produced within the digestive tract (through the oesophagus or anus)
Why do cows have so much gas?
- fermentation in the rumen generates 30-50 L per hour of gas in cow
- carbon dioxide and methane produced by the microbes
What happens if an animal fails to eruct?
- result in ruminal tympany (bloatedness)
- ruminal tympany is life-threatening
- interferes with breathing
- results in suffocation
