Fat Flashcards
Why should fats be added to the diet?
- decrease dust
- lubricate fee processing
- binder
- glossy hair coat
- increase diet energy density
- provide EFAs
Lipid classification (R)
- simple lipids - esters of FAs and various alcohols (TG)
- compound lipids - phospholipid
- derived lipids - derived from hydrolysis of simple and compound lipids that still possess the general properties of lipids
- Sterols - lipids with complex ring structure (cholesterol)
FA nomenclature depends on? (R)
- chain length
- degree of saturation (# DB)
- orientation of DB (usually cis)
Which FAs are essential?
linoleic and alpha linolenic acids
- cell membrane formation
- precursors of eicosanoids –> PGs, leukotrienes, thromboxanes (oxygenation)
What is the structure of a triglyceride?
one molecule of glycerol + 3 FAs
What are sterols?
- most common cholesterol
- essential component of cell membranes
- serves as precursor for:
1. vitamin D
2. chalice acid
3. steroid hormones
Functions of phospholipids?
- formation of cell membranes
- important constituent of lipoproteins
- thromboplastin
- nervous system insulators
- donors of phosphate radials
What are glycolipids?
- 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)
How do lipids get to horse?
- ingested in feed
- released from storage (long term negative energy balance or between meal energy release)
- synthesized by liver (triglycerides)
When would there be a need for significant release of lipids between meals?
when glucose funds out
What is the problem regarding the structure of fat?
fats are insoluble, but enzymes of digestion require an aqueous environment
- therefore, must be emulsified by biliary salts
Explain fat digestion
- 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
More energy means?
- increased growth rates, milk production, reproduction efficiency, physical performance
Explain the process of fat metabolism in the liver
Using lipoprotein lipase
- hydrolyze TG –> FFAs and glycerol
Fatty acids –> adipose + skeletal muscle (used as fuel or storage)
TG –> liver (glucose synthesis)
Fat as an energy source
- FA oxidation (in liver) –> acetyl CoA (citric acid cycle)
- ketogenesis - acetyl CoA –> acetoacetate + hydroxybutyrate (ketone bodies) = important metabolic fuel for cells outside of liver
Essentiality of dietary fat for horses
- to absorb fat soluble vitamins (A,D,E,K)
- to provide source of linoleic and (n-6) linolenic acid (n-3)
General feeding guidelines
2% BW forage –> addition of grain as carb/protein source –> fat for extra energy
What’s commonly seen if grain is fed at too high a concentration?
digestive disorders - colic and impaction
What is recommended fat inclusion?
10%
- can tolerate up to 20%
What happens to nutrient efficiency as a horse becomes more fit?
Training increases efficiency of utilization of fat and may spare glycogen
- more efficient with their use of energy and ability to use fat
Fat vs. CHO for energy
fat is more efficient in muscle but CHO produces energy faster
What factors affect TG storage?
training and age increases capacity for TG storage
- don’t affect glycogen mobilization during high intensity exercise
What is the thermic effect of feeding?
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
What makes fat > carbs
- good source of energy
- produces less heat than carbs
- produces lower heart rates than carbs
- maximum preference from consumption
Results from feeding n-3 fatty acids
- 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
Exercise’s effect on free radical formation
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
What is lipoic acid
- 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)
What is hyperlipidemia?
- often occurs in small pony breeds
- high TG concentrations
- can also occur in exercising or hypophagic horses
- increases with age & more common in mares
What is the cause of hyperlipidemia?
insulin resistance and negative nitrogen balance
- insulin required for AA transport and stimulates protein synthesis –> shift in body composition (decreased lean mass, increase adipose)
When is hyperlipidemia most common?
late gestation & lactation = inappetence, starvation, parasitism, lactation, stress (negative energy balance due to metabolic response or increasing energy expenditure)
What are symptoms of hyperlipidemia?
lethargy and depression
Treatment for hyperlipidemia?
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
Practical benefits of supplemental fat
- 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
Animal fats
- solid at room temperature
- by product
- restaurant fat/grease
vegetable fats
- liquid at room temperature
- corn, soybean, sunflower
saturated fatty acids
palmitic and stearic
unsaturated fatty acids
oleic, linoleic, linolenic, arachidonic
Which fats are susceptible to rancidity?
unsaturated - decomposition = hydrolysis and oxidation –> highly reactive peroxides
What is rancidity?
- 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
Prevention of rancidity
- 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
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?
- heat, moisture, light, pro-oxidants
- horse owners can buy whole grains
- processing grains can increase exposure to oxygen and increase oxidation & rancidity
