Lecture 15 lipids and Ruminants Flashcards
Whos diet are normally quiet low in lipids? and why?
Herbivores, 2-5% because plan food contains very small quantities of lipids
What is altered extensively by the rumen fermentation?
Plant lipids
The lipid actually received and absorbed by the animal differs from that ingested.
What is the ruminant intolerant to ?
High levels of fat, which may disrupt fermentation.
What are toxic to microbes?
Excess fatty acids
Where do ruminants obtain lipids from? what sources?
1-Forages (Glycolipids)
2-Grains&Concentrates(Triglycerides)
3- Fat Supplements (added to diet to increase energy density)
What are the usual fat sources in ruminants diet?
Oil seeds and animal fat supplementation
What is supplemented as an energy source in ruminants?
Dietary fats.
It proves more energy than carbohydrates.
Why would fat be supplemented in a ruminant?
To match the nutrient requirement of high production
What does too much fat in ruminant diet affect?
Digestibility
What happens after esterified plan lipids are consumed?
They are hydrolysed extensively by microbial lipases, causing the release of fatty acids and a free glycerol
What are lipases secreted by?
The microbes
What does the lipase hydrolyse in ruminants?
Hydrolysis acylglycerols completely to
-Fatty acids
-Glycerol
-Galactose
(If the lipid was a galactose) with little accumulation of mono or diglycerides.
What are rapidly fermented in the rumen?
Glycerol and Galactose, yielding VFA’s
What are the 2 VFA’s that are primarily fermented from glycerol and galactose?
Propionic and Butyrate
What happens during Rumen Biohydrogenation?
Dietary lipids are hydrolysed in the rumen to form free fatty acids and glycerol.
Where are triglycerides found?
Animals, Plants, Humans
Where are glycoproteins found?
Forages
What are phospholipids made up of?
2 fatty acids + 1 phosphate group
What are glycolipids made up of?
Glycerol with 2 fatty acids and 1 sugar “hanging off” SN3 position
What are triglycerides made up of?
3 fatty acids hooked onto glycerol backbone
What does biohydrogenation convert?
Unsaturated fatty acids to saturated fatty acids.
They then take biochemical pathways.
They are Biohydrogenation intermediates.
What must biohydrogenation have to be?
Must be a free fatty acid. If it remains as a TG, GL, PL then the FA cannot be hydrogenation.
What happens to fatty acids that get more hydrogen?
they are more saturated
What do unsaturated FA have a relatively short half of?
Lives in ruminal contents because they are rapidly hydrogenated by microbes to more saturated end products.
Whats the initial step in biohydrogenation?(BH)
An Isomerization reaction that converts the Cis-12 double bond in unsaturated FA’s to a trans-11 isomer.
What makes the isomerase functional?
a free carboxyl group, and in this case PUFA;s such as C18:2, a cis-9, cis-12 double bond configuration is present.
What establishes lipolysis as a prerequest for biohydrogenation?
The requirement of a free carboxyl group establishes lipolysis as a prerequisite for biohydrogenation
Name the 2 different types of fatty acid isomearse?
-cis
-trans
What happens when isomerization occurs?
Cis oriented double bond is joined by bacterial isomerases to be then transferred to trans Oriented double Bond
What is often not complete in terms of biohydrogenation?
The hydrogenation of linoleic and linolenic acid is often not complete
What does the incompleteness of linoleic and linolenic acid provide?
It provides stearic acid and different monounsaturated isomers, of which trans vaccenic acid is characteristic of ruminal metabolism.
What converts unsaturated double bonds to saturated bonds?
Bacterial Hydrolyses + H+
Why biohydrogenation?
Because it relieves the rumen of excess hydrogen ions: generated from fermentation.
Whats highly toxic to rumen bacteria?
PUFA’S
Whats the survival process of bacteria?
PUFA’S, different bacteria do different things.
What is the makeup of linoleic acid?
18:2
Whats the make up of steric acid?
18:0
What do ruminants consume alot of?
PUFA’S
Whats the ruminant lipid characterised by?
A higher saturated fat content (often criticised for too much saturated fat)
Whos is responsible for ruminant lipid?
Rumen biohydrogenation is responsible, ruminant lipid doesn’t resemble consumed FA
What does a monogastric lipid resemble?
The FA profile of what the animal consumed
