Rumen Lipid Metabolism Flashcards
% of cattle diets of lipids?
2-4%
major lipids in dairy cows
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
once triacylglycerols & phospholipids are hydrolysed in the rumen and are realeased from ester combination they unsaturated fatyy acids are hydrogenated by bacteria, yielding first…..
monotonic acid and untimely stearic acid
the lipid content of ruminants diets is normally XXX if it is increased above 100g/kg the activities of the rumen microbes are Y
50 g/kg
reduced
rumen hydrolysis Anaerovibrio hydrolyses what…?
triglycerides
butyrivibrio fibrisolvens hydrolyses
phospholipids and glycolipids
What enzyme is secreted by bacteria and involved with lipolysis
Lipase
fatty acids are absorbed where?
SI
% of f ingested UFA will be bio- hydrogenated to
produce SFA
90
which occurs faster lipolysis or biohydrogenation
lipolysis
Biohydrogenation
- ingested UFA are released from glycerol backbone in lipolysis and hydrogenated to SFA
- 90% of ingested UFA will be bio-hydrogenated to produce SFA
PUFA
Polyunsaturatedfattyacid
Linoleic acid—>(isomerase, Butyrivibrio fibrosolvens) Conjugated linoleic acid—->vaccenic acid—–>stearic acid
why biohydrogenation ?
- aid in relieving the rumen of excess H2 ions cause be constant acid production through normal fermentation
- PUFA highly toxic to rumen bacteria
How is fat absorbed
as micelles in the small intestine
what are micelles consisting of
bi layer consisting of bile salts, phospholipids and insoluble lipids in the middle
why are micelles needed
to move FA to the surface of intestinal cells where they can be absorbed
fat metabolism
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
tricglyerides in chylomicrons are broken down to what by what
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
about X the fat in milk is derived from the uptake of FA
HALF
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
Liver & fat mobilisation
- Periods of underfeeding and early lactation
cows mobilize fat to meet energy demand - FA taken up the liver and used as energy or
converted to ketones - Ketones released into blood and can be used
as an energy source - Liver has low capacity to export the FA so the
FA are deposited - Metabolic disorders (Ketosis and fatty liver)
