fibre ferm Flashcards

1
Q

why cant monogastrics breakdown fibre

A

due to the beta glucan bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is the reducing end in terms of polysaccharides ?

A

the end of the polysacc with an anomeric C1 not involved in a glycosidic bond.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

which polysaccharide is a glucose polymer with an alpha 1-4 linkage

A

amylose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is difference between amylose and amylopectin ?

A

amylopectin has alpha 1-4 linkages but also has branches formed by alpha 1-6 linkages.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

how is glycogen rapidly available ?

A

has more alpha 1-6 linkages and highly branched structures permit rapid glucose release.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what type of linkage is cellulose ?

A

beta 1-4 linkage
2 hydrogens on opposite sides of linkage hence beta.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

does more carbon FA’s in substrate increase or decrease energy

A

increase energy
butyrate highest carbons hence highest amount of energy.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

why is high concentrate diet better than high forage diet

A

larger intake of feed less fibre and animal can harvest more energy from the diet.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what substrate does cellulose, starch and sugars go through to make butyrate, propionate and acetate.

A

pyruvate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

does high pH result in more acetate or propionate being produced ?

A

acetate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

does low pH result in more acetate or propionate being produced ?

A

propionate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what 3 factors affect fibre fermentation

A
  1. rumen pH
  2. rumen passage rate
  3. diet digestibility
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what diets cause increase in VFA production

A

high starch diets

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

how does low pH impact fermentation ?

A
  1. microbial growth reduced
  2. energy once used for microbial production now diverted to maintain neutral pH.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is the impact if passage rate is too high?

A

can reduce digestibility

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

which structures have rapid passage rate

A

simple structures eg sugars

17
Q

which structures have slow passage rate ?

A

complex structures with high structural fibre content

18
Q

what controls the flow of digesta out of rumen ?

A

reticulum
abomasum

19
Q

why is optimum passage rate needed ?

A
  1. allow time for microbial fermentation
  2. absorbtion of VFA’s needs to occur
20
Q

what is % of NDF that is essential in diets

A

30%

21
Q

definition of degradability ?

A

how rapidly is feedstuff degraded in the rumen

22
Q

definition of digestibility ?

A

how much of the nutrient consumed is digested and absorbed in the GI.

23
Q

3 ways fibre of feedstuff is measured ?

A
  1. in Sacco
  2. in vitro
  3. NIR (infrared)
24
Q

why does drop in rumen pH lead to drop in fat comp ?

A

leads to less acetate in mammary gland which is used to take up fat.

25
Q

what can second rotation grass result in ?

A

drop in rumen pH and butterfat as it is highly fermentable.

26
Q

what is the biggest challenge with forage only diets ?

A

trying to get enough rapidly digestible carbs to maintain rumen function.

27
Q
A