Lecture 5 Flashcards
Are lipids a concentrated source of energy?
Yes
Lipids are found at relatively low levels in most plant with the exception of?
Oilseeds
What determines if a lipid is fat or oil?
Chain length and degree of saturation
- Long Chain and saturated fatty acids tend to produce fats
- Short chain and unsaturated fatty acids tend to produce oils
What are important unsaturated fatty acids?
-IMPORTANT
Oleic C18:1
Linoleic C18:2
Linolenic C18:3
Arachidonci C20:4
Most fats and oils are highly digestible
5 Reasons for lipid supplementation
Provide Energy
Provide Essential Fatty Acids
Alleviate Heat stress
Increase palatability
Lubrication
How much more energy do lipids have compared to carbohydrates?
2.25 X greater energy in lipids
3 Essential fatty acids
Linoleic C18:2
Linolenic C18:3
Arachidonic C20:4
5 symptoms of essential fatty acid deficiency
Kidney Lesion
Dermatitis of the back and feet
Cessation of growth
Necrosis of tail
Reproductive Failure
What are 2 types of rancidity?
Hydrolytic
Oxidative Rancidity
Explain hydrolytic rancidity
Involves cleavage of of ester bond between glycerol and FFA
Explain Oxidative Rancidity
Oxygen reacting with unsaturated fatty acids to produce aldehydes and ketones
What accelerates oxidative rancidity?
Pro-oxidants
- Heat
- UV light
- Moisture
What prevents oxidative rancidity?
Anti-oxidats
- Vitamin E
- BHA
- BHT
5 ways of determining lipid quality in feed mill
Titre (melting point)
Iodine Value
Saponfication Number
Total Fatty Acids
Free Fatty Acids
What is iodine number?
Number of g of iodine absorbed by 100g of lipid
High iodine number = large number of double bonds
What is the saponification number?
Number of mg of NaOH needed to saponify 1 g of fat
Saponify means to produce soap
Higher the number shorter the chain length
What are FFA?
Fatty acids not linked to glycerol by an ester linkage
What does unsaponifiable material do?
Lowers the energy value of the fat
What are most lipid in diet in the form of?
Triglycerides
Neutral Fats
Where is the principle site of lipid digestion?
Small intestine
WHy does lipid digestion not occur in stomach?
Too acidic for lipid digesting enzymes
What are two main problems specific to lipid digestion?
Digestive enzymes are proteins and therefore water soluble
Lipids are insoluble in water
3 hormones of lipid digestion
Secretin
Pancreozymin
Cholecystokinin
Where are secretin and pancreosymin formed, and what do they do?
Formed in duodenum
Stimulate release of digestive enzyme in pancrease
What does cholestokinin do?
Induces contraction and emptying of gall bladder which contains bile
What does bile do?
Connection between water and oil
Can live in both lipid and aqueous environment
Has a lipophilic end a hydrophilic end
What is the first step in lipid digestion and how does this occur?
Break the lipid globules into smaller sizes
Bile lowers surface tension of lipid globule and allows lipid globules to be broken down my churning of intestine
THis is all known as emuslification
Stiring oil in glass of water with spoon
What is the most important enzyme in lipid digestion?
Lipase
3 enzymes of lipid digestion
Pancreatic lipase
Cholesterol esterase
Phospholipase
How are phospholipids digested?
Phospholipase
Most phospholipid remains undigested, what is it used in the formation of?
Chylomicorns
also part of micelle formation
Are most end products of lipid digestion soluble or insoluble in water?
Insoluble
Fatty acid solubility
FA<10C are soluble in water
FA>10C are insoluble in water
What is a micelle?
Small spherical globules composed of 20-50 molecules of bile salt
Form a ring around fatty acid and monoglycerides allowing them to be transported in water
What is a chylomicron?
Large droplets of lipid surrounded by a shell of protein, phospholipids and cholesterol
- They are too large to pass directly in blood stream, transported in lymphatic vessels
Immediately after a lipid containing meal the chylomicron concentration will rise causeing the blood to take on a milky appearance
Where do chylomicrons transport lipids to to be stored?
Adipose cells
What occurs if there is insufficient carbohydrate availab.e?
Not enough CHO for fat to be oxidized to enter TCA cycle and therefore FAT becomes acetone which is a ketone
