Fatty Acid Composition

Question 1

What is the main form of fat that we and cattle store ourselves?

Answer 1

Triglycerdes: Have a glycerol backbone and 3 fatty acids

Question 2

What fats are found in the membranes of our cells?

Answer 2

Phospholipids: Have a glycerol backbone, a polar phosphate group and 2 fatty acids

Question 3

What are the chemical differences between saturated, monounsaturated and polyunsaturated fatty acids?

Answer 3

Fatty acids are made of H and C. They are made up of C chains with an acid group on one end.

• When all of the bonds in the C chain are taken up by H, = SATURATED
• When the chain contains 1 double bone = MONO UNSATURATED
• When the chain contains > 1 double bond = POLY UNSATURATED

Question 4

Beef fat tends to be what kind of fatty acid?

Answer 4

SATURATED because of the effect of biohydrogenation in the rumen –> higher melting point.

Question 5

What is an example of a saturated fatty acid?

Answer 5

Stearic acid, Palmitic acid

Question 6

What is an example of a monounsaturated fatty acid?

Answer 6

Oleic acid & Palmitoleic (cis), Vaccenic acid (trans)

Question 7

What is an example of a polyunsaturated fatty acid?

Answer 7

Linoleic acid & Arachidonic (omega 6),
Linolenic acid, EPA, DHA (all omega 3s)

Question 8

What are the CLA’s?

Answer 8

A group of Fatty acids. (a type of PUFA).

CLA’s have 18 Cs and 2x double bonds separated by 2 Cs.

E.g. Rumenic acid is a good CLA: is only available in rumenic products. Thought to have beneficial effects in terms of reducing effects of coronary heart disease and cancer aswell.

Question 9

How does the Delta System for Nomenclature of fatty acids work?

Answer 9

The Delta System numbers carbons from the acid or ‘Delta’ end.

Question 10

How does the Omega System number Carbons for nomenclature of fatty acids?

Answer 10

The Omega System numbers carbons from the methyl or “Omega” end

Question 11

T/F: When cattle eat, rumen bacteria rapidly hydrolise lipids to release free fatty acids

Answer 11

TRUE.

In a few steps, bacteria shift double bonds and add H.

Question 12

What fatty acids are toxic to bacteria?

Answer 12

PUFA.

Linoleic and linolenic acids are rapidly hydrogenated in the rumen

Question 13

How do cattle obtain essential fatty acids?

Answer 13

from the diet.

Forages are a source of linolenic acid (omega 3)
Grains are a source of linoleic acid (omega 6) - undesirable AAs
Oilseeds have a higher levels of linoleic acid (omega 6)
Flaxseed has a high lervel of linolenic acid (omega 3)
Algae, fish oils and fish meals have high levels of long chain Omega-3s such as DHA

Question 14

T/F: Levels of Unsaturated FA’s in milk of cows is higher in those fed a pasture diet than in hay + corn fed diet

Answer 14

True

Question 15

At a lower pH you get more biohydrogenation, what is the end effect?

Answer 15

more undesirable trans fats

Question 16

What are some efforts to combat the switch to undesirable 10t-18:1 producing species back to healthier 11t-18:1 producing species?

Answer 16

• Adding buffer - found to improve both the trans and CLA profile (effects only short term)
• Adding distiller’s grains - found to improve both the trans and CLA profiles
• Trialled grass diet vs a 1-2 month grain finishing diet - grass more favourable profile
• Adding vitamins and antibiotics - antibiotics found to have little effect

Question 17

What are some sources of Omega 3s?

Answer 17

Linolenic acid - flaxseed, hemp, canola, soy, nuts an dark green leaves.

EPA & DHA - fish oils & marine cold water species.

Question 18

What are some sources of Omega 6s:

Answer 18

Linoleic acid - sunflower linola, safflower oil, hemp, soy, nuts, sesame, pumpkin & flax.

• grains are a source of linoleic (omega 6)