ANSC 315 Lipids

2 classes of lipids

• fats

• oils

lipid solubility

• insoluble in water

• soluble in organic solvents like ether and chloroform

functions of lipids

• long term energy reserve

• insulation

• structural component of cell membranes

• components of enzyme systems

• components of steroid hormones

• fat-soluble vit absorption, synthesis

simple lipids

• fatty acids

• triacylglycerols

• waxes (structural and synthesis)

compound lipids

• phospholipids (cell membrane)

• glycolipids (grasses and cereal)

• lipoproteins (absorption and transport of lipids)

saturated

• 4-24 carbon atoms

• solid at room temp

unsaturated

• has c=c bonds

• shorter chain

• liquid at room temp

monounsaturated (MUFA)

when there is 1 c=c

Polyunsaturated (PUFA)

had 2 or more c=c

cis configuration

• usually liquid

• same side

• usually the form of natural occurring lipids

trans configuration

• usually solid

• opposite side

• occur due to rumen fermentation

delta system

counts from carboxyl end

• #c;#of =, triangle ^ where = are

omega system

counts from the methyl end

• #c;#of =, omega ^ where first = is

essential fatty acids

• linoleic acid

• alpha-linolenic acid

desaturase enzymes animal lack

• delta 12

• delta 15

desaturase enzyme animals have

delta 9, will turn c-c into c=c at carbon 9

symptoms of fatty acid deficiency

• retarded growth

• kidney lesion

• dermatitis of back, feet

• necrosis of tail

• reproductive failure

• early death

omega 6

excessive linked to caner, heart disease

omega 3

brain development, anti-carcinogenic, anti-atherosclerosis, etc.

feeds that are high in lipids

• canola

• soybean

• sunflower

• safflower

• flax

lipids in animal tissue

• major form on energy source

• amount is variable

types of body fat

• constant: structural component found in membranes, nerves, blood, and constantly required

• variable: fat reserves

triacylglycerols

• glycerol backbone

• 3 fatty acids

• release H2O in reaction

phospholipids

• glycerol molecules

• 2 fatty acid

• polar head group

• hydrophilic head and hydrophobic tail

functions of phospholipids

• component of cell membranes - bilayer

• lipid transport as part of lipoproteins

lipoproteins

• hydrophobic core

• hydrophilic surface monolayer

• lipid transport in blood

glycolipids

• contains glucose or galactose, FA, N base

• structural role in cells

• cerebrosides, gangliosides found predominantly on the brain and nerve tissue

• grasses rich in glycolipids

cholesteryl ester

• ester bond

• fatty acid

cholesterol as a precursor

• progesterone

• testosterone

• estradiol

• cortisol

• vit D3

short chain fatty acids

up to 8 carbons

medium-chain fatty acids

10-16 carbons

long chain fatty acids

over 18 carbons

digestibility of fats and oils

• effect by degree of saturation

• unsaturated is more digestible case c=c bond reduces packing together and increase enzyme penetration

• increasing chain length decreases digestibility

reason for lipid supplementation

• provide energy

• increase palatability

• provide fat-soluble vitamins

• provide essential fatty acids

• alleviate heat stress

• dust control

• lubrication

• improve diet handling

heat stress diet management

will cause a decrease in feed in take so…

• decrease carbs and increase lipids in diet

additional benefits of lipids outside of nutritional needs

• reduced dustiness of feed

• increases palatability

• lubricates feed mixing equipment

location of lipid digestion

• primarily small intestine

• lingual lipase in mouth

• gastric lipase in stomach

emulsification

• reduces TG from large fat globules to tiny droplets

• creates bigger surface area for enzyme activity

phases of lipid digestion in small intestine

1. emulsification

2. hydrolysis

3. micelle formation

4. absorption

bile salts

made in liver and stored in the gallbladder

lipase

digest lipid

colipase

removes bile salts

phospholipase; cholesterol esterase

frees up cholesterol and fatty acid

structure of micelles

• bile salts form edge

• NEFA, monoglycerides, cholesterol, lysophospholipids exist in bilayer

micelle disintegration

occurs when micelle interacts with microvilli and disintegrate when they touch the apical membrane in the small intestine

mechanisms of absorption

• passive diffusion

• fatty acid transport protein

lipid absorption in the small intestine

• short chain: absorbed straight into bloodstream

• medium/long chain: get use to make triglycerides

• NEFA: make phospholipids

chylomicron

• transport dietary lipids

• phospholipids point outwards to let it interact in aqueous condition (lymphatic system)

• released into lymphatic circulation via exocytosis

lipoproteins

transport endogenously produces lipids

transport of dietary fat

• chylomicrons transport TG to adipose

• lipoprotein lipase expressed in adipose ad hydrolyzes TG to NEFA and glycerol

• NEFA released into blood and use by peripheral tissues for energy

• glycerol used for energy

ketone bodies

• acetoacetate

• beta-hydroxybutyrate

• acetone

synthesis of fatty acids

• fatty acid elongation

• add acetyl CoA