Digestive System 4

Question 1

What is the order of stomachs in a cow ?

Answer 1

1. Rumen
2. Reticulum
3. Omasum
4. Abomasum

Question 2

How much live weight is in the rumen ?

Answer 2

10-20%

Question 3

What is live weight ?

Answer 3

The weight of the animal alive

Question 4

How much saliva do cows produce a day ? How much of the rumen is water ?

Answer 4

150L
85-93% water

Question 5

What is the histology of the rumen ?

Answer 5

Keratinised Stratified squamous epithelium
Contains ruminal papillae

Question 6

How many hours do cows spend eating and ruminating ?

Answer 6

8 hours eating and 8 hours ruminating

Question 7

What do we know about the reticulo-rumen microorganisms?

Answer 7

Over 200 species identified, mostly anaerobic bacteria and fungi.
It is a chemostat- continuous process.

Question 8

What does fermentation of microorganisms cause ?

Answer 8

Produces volatile fatty acids (VFAs) which are absorbed

Question 9

What structural changes occur in the stomach during development?

Answer 9

At birth the abomasum is the largest stomach.
At 18 months the reticulo-rumen occupies more than 90%

Question 10

What is the histology of the reticulum ?

Answer 10

Keratinised stratified squamous epithelium

Question 11

What is the Muscularis mucosa in ruminants ?

Answer 11

A ring of muscle around the top of each compartment that aids separation, mixing and breakdown of foods.

Question 12

What does the omasum do ?

Answer 12

Regulates entry of food into the abomasum.
Absorbs water and VFA absorption

Question 13

What does the omasum look like ?

Answer 13

A book

Question 14

What does the reticulum look like ?

Answer 14

Honeycomb

Question 15

What does the rumen look like ?

Answer 15

A fluffy blanket

Question 16

What are the features of the abomasum ?

Answer 16

Oesophageal groove
Glandular
Gastric pits
Parietal and chief cells

Question 17

What is the histology of the abomasum ?

Answer 17

Simple columnar

Question 18

What is cellulose ?

Answer 18

A chain of glucose units bound by beta 1,4 -linkages

Question 19

What do the intramoleculad hydrogen bonds in cellulose do ?

Answer 19

Decrease flexibility
Increase tensile strength
Decrease solubility in water

Question 20

What is lignin ?

Answer 20

A polymer of phenylpropane.
It forms a matrix around cellulose.
It increases strength under compression.

Question 21

Where is cellulose in cows digested ?

Answer 21

90% is digested in the reticulo-rumen

Question 22

What is cellulosome ?

Answer 22

Large, multienzyme complexes for adhesion and hydrolysis of cellulose

Question 23

What is starch made of ?

Answer 23

1. Amylose- glucose bound by alpha-1,4-linkages
2. Amylopectin- glucose bound by alpha-1,4 and 1,6-linkages

Question 24

Where is starch digested ? Into what ?

Answer 24

47-95% digested in the rumen
By alpha-amylase to oligosaccharides

Question 25

What are the three main volatile fatty acids ?

Answer 25

1. Propionate 2. Acetate 3. Butyrate

Question 26

How is protein digested in ruminants?

Answer 26

By microorganisms

Question 27

What are some advantages of ruminant digestion?

Answer 27

1. Utilise feeds too fibrous for non-ruminants 2. Produces high quality microbial protein from NPN 3. Produces vitamin B complexes

Question 28

What are some disadvantages of ruminant digestion ?

Answer 28

1. Large quantities of alkaline saliva needed 2. Large amounts of gas produced 3. Metabolic adaptation for VFA use

Question 29

What are the key features of cellulosome ?

Answer 29

1. CBD- cellulose binding domain, recognises and binds to cellulose 2. Hydrolyse domain- breaks down cellulose 3. It is bound into the bacterial cell wall