The Digestive System

Question 1

What is Solubility?

Answer 1

whether soluble in an aqueous environment; depends of physical properties

Question 2

What is Digestibility?

Answer 2

does host organism have the enzymes to digest

Question 3

What is Fermentibility?

Answer 3

do gut bacteria have the enzymes to break down (refers to carbs only!)

Question 4

What are the features of a Simple System (without functional caecum)?

Answer 4

• monogastric (one stomach)
• non-functional caecum
• hindgut fermentation (fermentation in the large intestine)
• nutrient dense, low fiber diet

Question 5

What are the steps of digestion in a simple system (without caecum)?

Answer 5

• oral cavity: food is chewed + mixed with alpha-amylase and lingual lipase
• stomach: has a pH of 2, food becomes chyme after 2-6 hours after being mixed with gastric juice composed of HCl and enzymes
• small intestine: chyme acidity is neutralized by pancreatic juice, and is digested by pancreatic juice and bile
• large intestine: water absorption, fermentation, and production of short-chained FAs

Question 6

What are the sections of the stomach in a simple system (without caecum)? (in order from top of bottom)

Answer 6

• cardia
• fundus
• body
• antrum

Question 7

What are the sections of the small intestine in a simple system (without caecum)? (in order from top of bottom)

Answer 7

• duodenum
• jejunum
• ileum

Question 8

Gut bacteria are mostly…(anaerobic or aerobic)

Answer 8

anaerobic

Question 9

True or False: everybody has the gut microbiota

Answer 9

false

Question 10

What are the features of a Simple System (with functional caecum)?

Answer 10

• pseudo-ruminant (only one stomach, and fodder is digested and fermented in the caecum)
• hindgut fermenter (fermentation in the large intestine)
• functional caecum

Question 11

What is Coptophagy?

Answer 11

when young eat their mothers poop to start colonizing their gut with bacteria

Question 12

What are the features of a Multiple System/Ruminant?

Answer 12

• foregut fermentation (fermentation in the stomach)
• 4 regions of the stomach
• suited for a high quantity of fodder and forage plant materials

Question 13

What are the sections of the stomach in a multiple system/ruminant, and their roles (in order of appearance)?

Answer 13

• reticulum: captures nutrients and foreign materials; rich in bacteria
• rumen: (largest section) contains papillae, rich in bacteria, and produces short-chained FAs
• omasum: reabsorption of water and filtering of large particles
• abomasum: secretion of digestive enzymes

Question 14

What are the pros and cons of a Multiple System/Ruminant (one of each)?

Answer 14

• pro: good for vitamin + protein synthesis
• con: eructation (regurgitating/belching) results in a loss of carbs, and excess heat production

Question 15

What is Digestibility?

Answer 15

measure of nutrient extracted by the GI tract; prevents deficiency and insures nutrients are available to the organism

Question 16

What are the 3 methods of measure digestibility?

Answer 16

• Total Collection Method
• Indicator Method
• True Digestibility

Question 17

How do you conduct a Total Collection Method digestibility test? (steps only!)

Answer 17

• animal adapts to diet for 7-21 days
• animal is isolated
• intake is measured over 3-10 days
• amount of feces is collected and analyzed

Question 18

What is the equation for Apparent Digestibility Coefficient using the Total Collection Method?

Answer 18

(total intake - total feces) / (total intake)

Question 19

What is the equation for Apparent Digestibility Coefficient using the Indicator Method?

Answer 19

(A - B) / (A) ; where A = nutrient/marker in FEED, B = nutrient marker in FECES

Question 20

What does the Total Collection Method measure?

Answer 20

Apparent Digestibility Coefficient

Question 21

What does the Indicator Method measure?

Answer 21

Apparent Digestibility Coefficient

Question 22

What does True Digestibility measure?

Answer 22

True Digestibility Coefficient

Question 23

How do you conduct an Indicator Method digestibility test? (steps only!)

Answer 23

• animal adapts of a test diet with marker/indicator
• feed is compared to fecal sample

Question 24

What is an External Marker?

Answer 24

a marker used for an indicator method digestibility test that is ADDED to the food

Question 25

What is an Internal Marker?

Answer 25

a marker used for an indicator method digestibility test that is ALREADY IN the food

Question 26

What does Apparent Digestibility NOT consider? (3)

Answer 26

• endogenous secretions/epithelial cells
• bacterial growth in gut/nutrient synthesis
• digestive enzymes/protein secretions

Question 27

How do you conduct a True Digestibility digestibility test? (steps only!)

Answer 27

• perform a digestibility study with a test diet
• switch diet to a 0 nutrient diet
• analyze feces from both diets

Question 28

What is the equation for True Digestibility Coefficient?

Answer 28

[A - (B - C)] / (A); where A = nutrient/marker in TEST DIET, B = nutrient/marker in feces, C = nutrient/marker in feces of 0 NUTRIENT DIET