Ruminal Fat Digestion

Question 1

What are 4 primary sources of lipids for ruminants?

Answer 1

1. Feed
2. Diet supplementation
3. Microbes
4. De novo synthesis

Question 2

What are some benefits (8) of adding fat to ruminant diets?

Answer 2

1. Increase energy density
2. Increase dietary energy without decreasing forage level
3. Less heat of fermentation
4. Change nutrient profile of products (ie. milk fat)
5. Health benefits
6. Decrease dustiness
7. Improve reproduction
8. Decrease methane production

Question 3

Why is it recommended not to exceed 8% of the total diet as fat/oil?

Answer 3

Interferes with rumen fermentation
a. coat fiber
b. toxic to microbes

Question 4

What is the best way to give fat to ruminants?

Answer 4

1. Whole oil seeds (soybeans, canola, sunflower)
2. High oil feeds (distillers grain, brewers grains, fish meal)
3. Unprotected oil (vegetable oil, animal fat)
4. Ruminally inert fats

Question 5

How do we measure dietary fat?

Answer 5

1. Ether extract (removes nutritive and non-nutritive fats)
2. Gas chromatography (measure feed lipids)

Question 6

What are 5 ways fatty acids are classified?

Answer 6

1. Chain length
2. Linkages (esterification)
3. Hydrogenation (sat, unsat)
4. Conjugation
5. Optical isomers (trans, cis)

Question 7

What is the difference between VFA, SCFA, MCFA, LCFA?

Answer 7

VFA: C1-C6
SCFA: C1-C8
MCFA: C10-C14
LCFA: C16+

Question 8

FFA vs NEFA? What is esterification?

Answer 8

free fatty acid, non-esterified fatty acid
Esterification means it is attached to glycerol back bone

Question 9

What does it mean when a fatty acid is saturated, mono-unsaturated, or polyunsaturated?

Answer 9

Saturated: no DBs, fully saturated
Mono-unsaturated: 1 DB
Poly-unsaturated: 2+ DB

Question 10

What is the difference between a conjugated and non-conjugated fatty acid?

Answer 10

Conjugated: DB are adjacent
Non-conjugated: DB have carbons between

Question 11

What is the difference between cis and trans fatty acids?

Answer 11

Cis: hydrogens on same side
Trans: hydrogens on opposite side

Question 12

What form (cis or trans) are fatty acids when they enter the rumen? When they leave?

Answer 12

Most dietary fats are in the cis form
Bacteria change them to trans form

Question 13

Omega vs Alpha

Answer 13

Omega carbon refers to methyl (-CH3) end
Alpha carbon refers to carboxyl (-COOH) end

Question 14

Essential FA required for?

Answer 14

1. prostaglandin synthesis
2. Phospholipid synthesis, cell membrane
   Animals unable to de novo synthesize

Question 15

Do microbes use fatty acids as an energy source?

Answer 15

No

Question 16

Are fatty acids (>10 carbons) absorbed across the rumen wall?

Answer 16

No

Question 17

What are the 3 steps in rumen lipid metabolism?

Answer 17

1. Hydrolysis
2. Biohydrogenation
3. Isomerization

Question 18

What is hydrolysis?

Answer 18

the breaking of ester bonds in triglycerides, make FFA

Question 19

What is biohydrogenation? Why does it occur?

Answer 19

Adds H+ to unsaturated FA
It is a detoxification

Question 20

What is isomerization?

Answer 20

Cis DB converted into trans DB

Question 21

How does ruminant and non-ruminant fat differ?