The Rumen

Question 1

The purpose of fermentation

Answer 1

• Transforms forage into simple sugars that rumen microorganisms can use for growth
• Cellulose cell wall broken by rumen microbes
• Produces VFAs (volatile fatty acids) major energy source

Question 2

What do microbes provide for ruminants?

Answer 2

• Cellulose digestion
• Provision of organic acids
• Protein provision
• Provision of B vitamins
• Detoxifying compounds

Question 3

What are VFAs + examples

Answer 3

Volatile fatty acids are short chained fatty acids, such as:
- Propionate
- Butyrate
- Acetate

Question 4

3 Phases of Rumen development

Answer 4

• Pre-ruminant
• Transitional
• Ruminant
  Moving from mono-gastric to ruminant

Question 5

Pre-ruminant phase (monogastric)

Answer 5

• Oesophageal Groove; mucular structure forms a tube that allows milk to go straight to abomasum
• Prevents milk being fermented

Question 6

Milk Replacement

Answer 6

• 5-6 litres of milk
• 13-15% of calf birth weight daily
• Minimum of two feeds
• Digested in abomasum

Question 7

Feeding concentrates

Answer 7

From 3-4 days old
- Digested in rumen
- Produces butyrate & propionate
- Increases papillae number
- High energy reduces gut-fill

Question 8

Feeding concentrates alone

Answer 8

• Causes hyperkeratinisation
• Causes clumping of papillae
• Decreases rumen motility

Question 9

Increasing size of rumen and muscular growth

Answer 9

Feeding fibre, forages (hay)
Produces acetate

Question 10

Summarise balance of feeding calves for rumen development

Answer 10

• Feeding concentrates; VFA production
  causes papillae development
• Feeding forages; bulk, rumination maximises size of rumen
• Calf starter by 3 days old, rumen development takes 21 days

Question 11

Challenges with breaking down fibre

Answer 11

• Fibre is a polysaccharide
• Glucans are beta-linked (cellulose)
• Mammalian enzymes can’t break these down
• Need to be fermented

Question 12

What is in the ecosystem of the rumen?

Answer 12

• Bacteria 10 billion/ml
• Protozoa 1 million/ml
• Fungi 1000/ml
  These microbes are free in liquid, attached to feed or lining of the rumen

Question 13

Retention in the forestomach

Answer 13

• Must be a long retention time in forestomach because fermentation is a long process

Question 14

Reticulum structure & function

Answer 14

• Honeycomb appearance
• Mechanical grinding and stores non-food objects
• Traps large food particles
• Regurgitation of ingesta

Question 15

Omasum strucure & function

Answer 15

• Contains many leaves like a book; their function is to squeeze water out of feed
• Water absorption & helps to grind up food particles

Question 16

Abomasum structure & function

Answer 16

• Glandular equivalent to mono-gastric stomach
• J- shaped
• Acid digestion; not a holding chamber

Question 17

Eructation

Answer 17

Belching; removes fermentation gases
Every second ruminal contraction
Methane is the main gas

Question 18

Saliva’s importance in rumination

Answer 18

• Neutralises 30% of acid produced in rumen
• pH of 8.2
• high phosphate content ( for microbial growth)

Question 19

What happens to the VFA’s?

Answer 19

• 70-80% absorbed from the reticulorumen
• 14-18% absorbed from the abomasum
• 3-11% of fermented energy lost as methane
  Transported to liver for processing

Question 20

Degradation of protein

Answer 20

• Breaks protein down into AAs
• Bacteria absorb and use some of the AAs to grow and live
• Byproducts are ammonia and VFAs- deamination

Question 21

Rumen degradable protein (RDP)

Answer 21

• Feeds rumen bacteria
• Ensures adequate supply of microbial protein

Question 22

Rumen undegradable protein (RUP/RUDP)

Answer 22

• Passes through rumen unchanged
• digested in small intestine