carbohydrates and dietary fibre

Question 1

what is the nutritional role of carbohydrates?

Answer 1

providing immediate energy and storing energy in the form of glycogen and adipose.

Question 2

what are the 2 primary energy nutrients

Answer 2

lipids and carbohydrates

Question 3

what is absorbed from the gut lumen

Answer 3

monosaccharides

Question 4

what carbohydrates do plants contain

Answer 4

cellulose
hemicellulose
lignin

Question 5

what are the major sources of plant carbohydrates

Answer 5

seed endosperm
plant fibres

Question 6

what does analysis of feed carbohydrate content provide

Answer 6

value for crude fibre

Question 7

what do plant cell walls require to be digested

Answer 7

require microbial fermentation to yield VFAs

Question 8

what are the cell contents

Answer 8

sugars and starches

Question 9

how are plant cell contents digested in ruminants

Answer 9

hydrolysed to glucose by mammalian enzymes but fermented as FME to yield VFAs by ruminants

Question 10

how are plant fibres digested in non-ruminants

Answer 10

have colonic bacteria which can digest some cellulose

Question 11

how to increase FME

Answer 11

provide cereals

Question 12

the effect of increasing FME by providing cereals in ruminants

Answer 12

increase rate of fermentation
synthesis of large quantities of VFAs reduces the PH of rumen contents so can cause rumen acidosis

Question 13

what is the main source of energy in ruminants?

Answer 13

volatile fatty acids

Question 14

process of absorption of VFAs

Answer 14

VFA absorbed across reticulorumen wall
remainder absorbed in omasum
transported to liver for processing

Question 15

why are simple sugars absorbed directly by ruminants

Answer 15

they are quickly taken up by rumen microbes and converted to VFA

Question 16

what is the normal rumen pH

Answer 16

6-7

Question 17

what happens to the pH after a meal in ruminants and why

Answer 17

VFA lowers the pH and is buffered by saliva

Question 18

what is formed in diets high in fibre in ruminants?

Answer 18

small amount of lactate formed and lots of ruminating hence saliva to buffer

Question 19

what happens in diets high in starch in ruminants

Answer 19

quickly fermented, more VFA produced, faster and larger amounts of lactate
less fibre means rumination and less saliva to buffer pH

Question 20

what is rumen a acidosis

Answer 20

low rumen pH

Question 21

what happens in monogastrics following cereal meals

Answer 21

gastric acid synthesis increased and products of digestion further depress gastric pH
causes gastric perturbations including ulceration and colic

Question 22

what is the effect on chewing and saliva production with diets high in fibre

Answer 22

increased time spent chewing which increases saliva production and neutralises acidic digesta

Question 23

benefits of a high fibre diet

Answer 23

reduced gastric abomasal ulceration
reduced stereotypies
reduced dental overgrowth
reduced digestive perturbations
improved digestibility

Question 24

the essential functions of fibre in cattle diets

Answer 24

stimulate cudding
form a rumen fibre mat which traps small particles for digestion and biofilm matrix

Question 25

what are the indirect nutritional effects of fibre

Answer 25

alters food intake
alters digesta transit time
alters fermentation rates
effects on microflora
alters digestive secretions
alters behaviour
alters body composition
alters milk fat
alters water intake
effects on metabolizable energy to digestible energy
effects on faecal apparent digestibility