Lecture 3- Pseudo-Reuminant/Ruminant/Avian Digestive System

Question 1

Pseudo-Ruminant Digestive System:

Answer 1

• Simple system with a functional caecum (lots of fermentation occurs in the caecum)
  
  • Functional caecum
  • Suited for a diet with large amounts of fodder
  • i.e. horses, rabbits hamsters

Question 2

Caecum:

Answer 2

• Enormous hindgut (20-30 L capacity) filled with bacteria
• SCFA provides 70% of total energy needs for host
Generates vitamins

Question 3

Coprophagy:

Answer 3

• Eating dung or feces

Signs of an energy or nutrient deficiency

Question 4

Absorption of Nutrients:

Answer 4

• Indigestible fibre passes through system
• Fermentable fiber broken down to SCFA/VFA in caecum
Bacteria can break down starch into lactic, bad for horses, diet shouldn’t be too high in sugars or starch (can lead to colic)

Question 5

Ruminant System:

Answer 5

• Cattle, sheep, goats
• Large stomach divided into 4 sections
○ Rumen
○ Reticulum
○ Omasum
○ Abomasum
• System highly suited for animals that eat a high quantity of fodder
• 4 gut fermenter (fermentation occurs before small intestine)
○ Bidirectional esophagus- after mixing, regurgitated and chewed again
• Fermentation takes place before entering the intestine (foregut digestion)
Nutrients produced by bacteria then become available for digestion and absorption by the ruminant

Question 6

Reticulum-Ruminant:

Answer 6

• Honeycomb appearance in order to capture nutrients and trap foreign materials (wire, nails, etc)
Rich in bacteria (fermentation vat)

Question 7

Rumen-Runimant:

Answer 7

• Largest section of the stomach
• Rich in bacteria (fermentation vat)
• Covered in rumen papillae (increases surface area for absorption- like microvilli in the human intestine)
• Food is mixed and partially broken down, and stored temporarily
• 60-80% of total energy produced here through SCFA
Has 10-50 billion bacteria/ g of ruminal fluid

Question 8

Omasum-Ruminant:

Answer 8

• Resorption of water and some electrolytes

Filters large particles

Question 9

Abomasum-Ruminant:

Answer 9

• Digestive enzymes secreted from gastric glands (HCl, mucin, pepsinogen, lipase…etc)
“true stomach”, similar to that of monogastric animals

Question 10

Rumination:

Answer 10

• Nutrients are consumed, mixed, and fermented

* Food regurgitated, process repeats

Question 11

Eructation (Belching):

Answer 11

• Breakdown of food produces large amounts of CO2 and methane
Belching allows for removal or cow would explode

Question 12

Advantages and of a Ruminant System:

Answer 12

○ Vitamin synthesis
○ Non protein nitrogen used for making protein
Essential amino acids derived from bacteria (bacteria breaks down low quality amino acids and turns it into essential amino acids)

Question 13

Disadvantages of a Ruminant System:

Answer 13

○ Carbohydrates degraded into gases and lost through eructation
○ Heat production
High levels of fermentation produces a lot of heat (lots of energy lost as heat)

Question 14

Avian System:

Answer 14

• Beaks and claws are important for breaking up foods into smaller pieces that birds can swallow
• Rapid digestion
○ Birds are constantly eating and digesting food
○ Evolutionary advantage- need to be able to fly away if necessary, eating a large meal makes it hard to move

Question 15

Crop-Avian

Answer 15

• Enlarged area of the esophagus
• Well developed in most species, but not all
• Temporary storage location for food
Food is softened (often regurgitated to feed offspring)

Question 16

Two Chamber Stomach-Avian:

Answer 16

• Proventriculus- glandular portion
		○ Secretes gastric enzymes and HCl
	• Gizzard
		○ Muscular portion
		○ Grinds and digests tough foods
Chickens will swallow stones, stones accumulate in gizzard

Question 17

Small Intestine- Avian:

Answer 17

Functions similar to that in other systems

Question 18

Ceca-Avian

Answer 18

Minor site of bacterial fermentation

Question 19

Large Intestine-Avian

Answer 19

• Very short, serves predominantly to connect small intestine and cloaca
• Water absorption
Minor storage function of undigested material

Question 20

Cloaca-Avian

Answer 20

Digestive, urinary, reproductive systems converge