Fat

Question 1

Why should fats be added to the diet?

Answer 1

• decrease dust
• lubricate fee processing
• binder
• glossy hair coat
• increase diet energy density
• provide EFAs

Question 2

Lipid classification (R)

Answer 2

1. simple lipids - esters of FAs and various alcohols (TG)
2. compound lipids - phospholipid
3. derived lipids - derived from hydrolysis of simple and compound lipids that still possess the general properties of lipids
4. Sterols - lipids with complex ring structure (cholesterol)

Question 3

FA nomenclature depends on? (R)

Answer 3

1. chain length
2. degree of saturation (# DB)
3. orientation of DB (usually cis)

Question 4

Which FAs are essential?

Answer 4

linoleic and alpha linolenic acids

• cell membrane formation
• precursors of eicosanoids –> PGs, leukotrienes, thromboxanes (oxygenation)

Question 5

What is the structure of a triglyceride?

Answer 5

one molecule of glycerol + 3 FAs

Question 6

What are sterols?

Answer 6

• most common cholesterol
• essential component of cell membranes
• serves as precursor for:
  1. vitamin D
  2. chalice acid
  3. steroid hormones

Question 7

Functions of phospholipids?

Answer 7

• formation of cell membranes
• important constituent of lipoproteins
• thromboplastin
• nervous system insulators
• donors of phosphate radials

Question 8

What are glycolipids?

Answer 8

• CHO + lipid
• important for structure in nerves, white matter in brain
• function by sending signals to accelerate cell transport and cell knowledge of different presented components (part of gate keeping system)

Question 9

How do lipids get to horse?

Answer 9

• ingested in feed
• released from storage (long term negative energy balance or between meal energy release)
• synthesized by liver (triglycerides)

Question 10

When would there be a need for significant release of lipids between meals?

Answer 10

when glucose funds out

Question 11

What is the problem regarding the structure of fat?

Answer 11

fats are insoluble, but enzymes of digestion require an aqueous environment
- therefore, must be emulsified by biliary salts

Question 12

Explain fat digestion

Answer 12

• occurs minimally in mouth (lingual lipase)
• mostly in small intestine (bile salts and lipase) –> mixed micelle (MAG, DAG, FFA, cholesterol, phospholipids) so they can be absorbed by enterocyte
• absorbed into intestinal epithelial cells (FA –> TAG) + binding proteins = lipoprotein complexes) AND cholesterol –> transportation (as chylomicrons)
• delivered via lymphatics and capillaries to tissues
• transported throughout body as chylomicrons
• digested fat provide over 2.25x more utilizable energy than equal weight of digested carb/protein

Question 13

More energy means?

Answer 13

• increased growth rates, milk production, reproduction efficiency, physical performance

Question 14

Explain the process of fat metabolism in the liver

Answer 14

Using lipoprotein lipase
- hydrolyze TG –> FFAs and glycerol

Fatty acids –> adipose + skeletal muscle (used as fuel or storage)
TG –> liver (glucose synthesis)

Question 15

Fat as an energy source

Answer 15

• FA oxidation (in liver) –> acetyl CoA (citric acid cycle)
• ketogenesis - acetyl CoA –> acetoacetate + hydroxybutyrate (ketone bodies) = important metabolic fuel for cells outside of liver

Question 16

Essentiality of dietary fat for horses

Answer 16

• to absorb fat soluble vitamins (A,D,E,K)

- to provide source of linoleic and (n-6) linolenic acid (n-3)

Question 17

General feeding guidelines

Answer 17

2% BW forage –> addition of grain as carb/protein source –> fat for extra energy

Question 18

What’s commonly seen if grain is fed at too high a concentration?

Answer 18

digestive disorders - colic and impaction

Question 19

What is recommended fat inclusion?

Answer 19

10%

- can tolerate up to 20%

Question 20

What happens to nutrient efficiency as a horse becomes more fit?

Answer 20

Training increases efficiency of utilization of fat and may spare glycogen
- more efficient with their use of energy and ability to use fat

Question 21

Fat vs. CHO for energy

Answer 21

fat is more efficient in muscle but CHO produces energy faster

Question 22

What factors affect TG storage?

Answer 22

training and age increases capacity for TG storage

- don’t affect glycogen mobilization during high intensity exercise

Question 23

What is the thermic effect of feeding?

Answer 23

Decreases the amount of dietary energy used for heat production

• decreases horse’s body hear loaf (doesn’t require a lot of energy to process)
• leaves more energy for other functions
• reduces plasma insulin concentration

Question 24

What makes fat > carbs

Answer 24

• good source of energy
• produces less heat than carbs
• produces lower heart rates than carbs
• maximum preference from consumption

Question 25

Results from feeding n-3 fatty acids

Answer 25

- increased plasma concentration - more flexible cell membranes = better cell signalling/communication - may improve hoof quality (and skin/coat) - may improve joint mobility (key for older horses) - may decrease skin inflammation - may increase infection resistance - may help sperm move better Ideal 6:3 = 10:1

Question 26

Exercise's effect on free radical formation

Answer 26

Acute exercise increases free radicals due to: - increased oxygen consumption and increases cellular respiration - increased catecholamines --> produce free radicals - tissue damage from intense exercise can also lead to lipid per oxidation of membranes - inflammatory responses can also produce free radicals

Question 27

What is lipoic acid

Answer 27

- thiol compound synthesized in the body (sulphur containing) - decreases exercise induced oxidative stress and improved oxidative metabolism - increases glucose uptake (acts in the TCA to help ameliorate free radical formation & increases flow of energy)

Question 28

What is hyperlipidemia?

Answer 28

- often occurs in small pony breeds - high TG concentrations - can also occur in exercising or hypophagic horses - increases with age & more common in mares

Question 29

What is the cause of hyperlipidemia?

Answer 29

insulin resistance and negative nitrogen balance - insulin required for AA transport and stimulates protein synthesis --> shift in body composition (decreased lean mass, increase adipose)

Question 30

When is hyperlipidemia most common?

Answer 30

late gestation & lactation = inappetence, starvation, parasitism, lactation, stress (negative energy balance due to metabolic response or increasing energy expenditure)

Question 31

What are symptoms of hyperlipidemia?

Answer 31

lethargy and depression

Question 32

Treatment for hyperlipidemia?

Answer 32

Treat concurrent disease, restoration of energy balance, correction of fluid and electrolyte imbalance - to correct energy balance provide something with high DE (beet pulp) - may need to improve diet palatability

Question 33

Practical benefits of supplemental fat

Answer 33

- prevent deleterious effects of excessive grain and inadequate forage intake - accomplish need for increased energy (without side effects of increased grain) - 1 cup oil = 1.5 lbs grain - 10% (2 cups) daily ration

Question 34

Animal fats

Answer 34

- solid at room temperature - by product - restaurant fat/grease

Question 35

vegetable fats

Answer 35

- liquid at room temperature | - corn, soybean, sunflower

Question 36

saturated fatty acids

Answer 36

palmitic and stearic

Question 37

unsaturated fatty acids

Answer 37

oleic, linoleic, linolenic, arachidonic

Question 38

Which fats are susceptible to rancidity?

Answer 38

unsaturated - decomposition = hydrolysis and oxidation --> highly reactive peroxides

Question 39

What is rancidity?

Answer 39

- accelerated by heat, moisture, light, pro-oxidants (metals) - reduced feed intake --> off flavours/odors - rancid fats can destroy vitamin A, carotene, vitamin E, other nutrients containing DB's

Question 40

Prevention of rancidity

Answer 40

- retarded by antioxidants - vitamin E and ethoxyquin - in whole grains, oils protected against rancidity by the compartmentalized plant cell structure - grinding high oil grains increases susceptibility to rancidity by lipoxygenase enzyme - heating full fat soybeans inactivates lipoxygenase

Question 41

Rancidity leads to reduced feed intake due to off odors and flavours. This process is accelerated by __________, ______________, _______________ and ___________. What is one method horse owners can use with respect to buying grains which will prevent rancidity?

Answer 41

- heat, moisture, light, pro-oxidants - horse owners can buy whole grains - processing grains can increase exposure to oxygen and increase oxidation & rancidity