Rumen Lipid Metabolism

Question 1

% of cattle diets of lipids?

Answer 1

2-4%

Question 2

major lipids in dairy cows

Answer 2

triglycerides: cereal grains, oilseed, animal fats & byproducts
2. glycolipids/galactoplipids; forages
3. Phospholipids- cell membrane of animal cells and surface fat globules
4. Free fatty acids; minor component if dairy feeds, major component of fat supplements

Question 3

once triacylglycerols & phospholipids are hydrolysed in the rumen and are realeased from ester combination they unsaturated fatyy acids are hydrogenated by bacteria, yielding first…..

Answer 3

monotonic acid and untimely stearic acid

Question 4

the lipid content of ruminants diets is normally XXX if it is increased above 100g/kg the activities of the rumen microbes are Y

Answer 4

50 g/kg
reduced

Question 5

rumen hydrolysis Anaerovibrio hydrolyses what…?

Answer 5

triglycerides

Question 6

butyrivibrio fibrisolvens hydrolyses

Answer 6

phospholipids and glycolipids

Question 7

What enzyme is secreted by bacteria and involved with lipolysis

Answer 7

Lipase

Question 8

fatty acids are absorbed where?

Answer 8

SI

Question 9

% of f ingested UFA will be bio- hydrogenated to
produce SFA

Answer 9

90

Question 10

which occurs faster lipolysis or biohydrogenation

Answer 10

lipolysis

Question 11

Biohydrogenation

Answer 11

1. ingested UFA are released from glycerol backbone in lipolysis and hydrogenated to SFA
2. 90% of ingested UFA will be bio-hydrogenated to produce SFA

Question 12

PUFA

Answer 12

Polyunsaturatedfattyacid

Question 13

Linoleic acid—>(isomerase, Butyrivibrio fibrosolvens) Conjugated linoleic acid—->vaccenic acid—–>stearic acid

Question 14

why biohydrogenation ?

Answer 14

1. aid in relieving the rumen of excess H2 ions cause be constant acid production through normal fermentation
2. PUFA highly toxic to rumen bacteria

Question 15

How is fat absorbed

Answer 15

as micelles in the small intestine

Question 16

what are micelles consisting of

Answer 16

bi layer consisting of bile salts, phospholipids and insoluble lipids in the middle

Question 17

why are micelles needed

Answer 17

to move FA to the surface of intestinal cells where they can be absorbed

Question 18

fat metabolism

Answer 18

in the intestinal epithelia cells the FA converted to tryglycerides by combing with glycerol from glucose metabolism

Triglycerides, free fatty acids, cholesterol and
other lipid substances are coated with protein
to form lipoproteins called chylomicrons or very
low density lipoproteins

Question 19

tricglyerides in chylomicrons are broken down to what by what

Answer 19

FFA By the enzyme lipoprotein lipase in the capillaries of these tissues

then FFA then enter cells where they can be formed back into triglycerides ( eg milk fat) oo burned to release energy to fuel cell functions

Question 20

about X the fat in milk is derived from the uptake of FA

Answer 20

HALF

Question 21

An increase in long chain fatty acids (>16 carbons) in the diet increases their secretion in milk
but synthesis of short & medium chain FA in inhibited

Question 22

Liver & fat mobilisation

Answer 22

1. Periods of underfeeding and early lactation
   cows mobilize fat to meet energy demand
2. FA taken up the liver and used as energy or
   converted to ketones
3. Ketones released into blood and can be used
   as an energy source
4. Liver has low capacity to export the FA so the
   FA are deposited
5. Metabolic disorders (Ketosis and fatty liver)