Lecture 5

Question 1

Are lipids a concentrated source of energy?

Answer 1

Yes

Question 2

Lipids are found at relatively low levels in most plant with the exception of?

Answer 2

Oilseeds

Question 3

What determines if a lipid is fat or oil?

Answer 3

Chain length and degree of saturation

1. Long Chain and saturated fatty acids tend to produce fats
2. Short chain and unsaturated fatty acids tend to produce oils

Question 4

What are important unsaturated fatty acids?

-IMPORTANT

Answer 4

Oleic C18:1

Linoleic C18:2

Linolenic C18:3

Arachidonci C20:4

Question 5

Most fats and oils are highly digestible

Question 6

5 Reasons for lipid supplementation

Answer 6

Provide Energy

Provide Essential Fatty Acids

Alleviate Heat stress

Increase palatability

Lubrication

Question 7

How much more energy do lipids have compared to carbohydrates?

Answer 7

2.25 X greater energy in lipids

Question 8

3 Essential fatty acids

Answer 8

Linoleic C18:2

Linolenic C18:3

Arachidonic C20:4

Question 9

5 symptoms of essential fatty acid deficiency

Answer 9

Kidney Lesion

Dermatitis of the back and feet

Cessation of growth

Necrosis of tail

Reproductive Failure

Question 10

What are 2 types of rancidity?

Answer 10

Hydrolytic

Oxidative Rancidity

Question 11

Explain hydrolytic rancidity

Answer 11

Involves cleavage of of ester bond between glycerol and FFA

Question 12

Explain Oxidative Rancidity

Answer 12

Oxygen reacting with unsaturated fatty acids to produce aldehydes and ketones

Question 13

What accelerates oxidative rancidity?

Answer 13

Pro-oxidants

• Heat
• UV light
• Moisture

Question 14

What prevents oxidative rancidity?

Answer 14

Anti-oxidats

• Vitamin E
• BHA
• BHT

Question 15

5 ways of determining lipid quality in feed mill

Answer 15

Titre (melting point)

Iodine Value

Saponfication Number

Total Fatty Acids

Free Fatty Acids

Question 16

What is iodine number?

Answer 16

Number of g of iodine absorbed by 100g of lipid

High iodine number = large number of double bonds

Question 17

What is the saponification number?

Answer 17

Number of mg of NaOH needed to saponify 1 g of fat

Saponify means to produce soap

Higher the number shorter the chain length

Question 18

What are FFA?

Answer 18

Fatty acids not linked to glycerol by an ester linkage

Question 19

What does unsaponifiable material do?

Answer 19

Lowers the energy value of the fat

Question 20

What are most lipid in diet in the form of?

Answer 20

Triglycerides

Neutral Fats

Question 21

Where is the principle site of lipid digestion?

Answer 21

Small intestine

Question 22

WHy does lipid digestion not occur in stomach?

Answer 22

Too acidic for lipid digesting enzymes

Question 23

What are two main problems specific to lipid digestion?

Answer 23

Digestive enzymes are proteins and therefore water soluble

Lipids are insoluble in water

Question 24

3 hormones of lipid digestion

Answer 24

Secretin

Pancreozymin

Cholecystokinin

Question 25

Where are secretin and pancreosymin formed, and what do they do?

Answer 25

Formed in duodenum Stimulate release of digestive enzyme in pancrease

Question 26

What does cholestokinin do?

Answer 26

Induces contraction and emptying of gall bladder which contains bile

Question 27

What does bile do?

Answer 27

Connection between water and oil Can live in both lipid and aqueous environment Has a lipophilic end a hydrophilic end

Question 28

What is the first step in lipid digestion and how does this occur?

Answer 28

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

Question 29

What is the most important enzyme in lipid digestion?

Answer 29

Lipase

Question 30

3 enzymes of lipid digestion

Answer 30

Pancreatic lipase Cholesterol esterase Phospholipase

Question 31

How are phospholipids digested?

Answer 31

Phospholipase

Question 32

Most phospholipid remains undigested, what is it used in the formation of?

Answer 32

Chylomicorns also part of micelle formation

Question 33

Are most end products of lipid digestion soluble or insoluble in water?

Answer 33

Insoluble

Question 34

Fatty acid solubility

Answer 34

FA\<10C are soluble in water FA\>10C are insoluble in water

Question 35

What is a micelle?

Answer 35

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

Question 36

What is a chylomicron?

Answer 36

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

Question 37

Where do chylomicrons transport lipids to to be stored?

Answer 37

Adipose cells

Question 38

What occurs if there is insufficient carbohydrate availab.e?

Answer 38

Not enough CHO for fat to be oxidized to enter TCA cycle and therefore FAT becomes acetone which is a ketone