ANFF topic 3 part 2 (2)

Question 1

What is feed extrusion?

Answer 1

• extrusion technique is a process in animal feed processing technology
• involves steam and water

Question 2

What does protein nutritional value depend on?

Answer 2

• quantity
• digestibility (MOST IMPORTANT FACTOR)
• availability of essential amino acids

Question 3

What enhances the nutritional value of protein?

Answer 3

• mild extrusion cooking conditions

Question 4

What happens when protein undergoes mild extrusion cooking conditions?

Answer 4

- destruction of anti-nutritional factors (which inhibit protein digestibility)
Examples of anti-nutritional factors:
- trypsin inhibitors
- haemagglutinin
- tannins
- phytates

Question 5

Which amino acid is the most affected during extrusions processing?

Answer 5

• lysine
• especially when cooked for too long
  The loss depends on:
• extrusion limiting conditions
• increasing with temperature
• decreasing with moisture content in the feed

Question 6

What happens to carbohydrates during extrusion cooking?

Answer 6

• gelatinizes starch at lower moisture levels

- changes in dietary fibre content

Question 7

What is starch gelatinization?

Answer 7

• process where starch and water are subjected to heat causing the starch granules to swell
• water is gradually absorbed in an irreversible manner
• viscous and transparent texture

Question 8

How is the quality and quantity of fat in feed maintained throughout extrusion?

Answer 8

• ‘over-coated’ or ‘top dressed’ of the feeds (after extrusion process)

Question 9

What happens to vitamins in feed during extrusion processing?

Answer 9

• decreases with increasing temperature

Question 10

How to ensure there is adequate amount of vitamins in feed throughout and after extrusion process?

Answer 10

• addition of extra amount of vitamin compounds to compensate losses during extrusion
• post extrusion application methods like dusting, enrobing, spraying, coating and filling

Question 11

What happens to minerals during the extrusion process?

Answer 11

• minerals are heat stable and unlikely to become lost during extrusion
• extrusion may improve the absorption of minerals by reducing other factors that inhibit absorption

Question 12

What can poor storage of feeds and ingredients lead to?

Answer 12

• animal mortality

- economic loss

Question 13

What are some environmental factors that can affect deterioration of feed?

Answer 13

• moisture (feed moisture content & relative humidity)
• temperature
• light (some might be light-sensitive & nutrients may be destroyed)
• oxygen

Question 14

How to reduce the deterioration of feed with regards to moisture?

Answer 14

• maintain as low as possible moisture content of both air and feedstuffs
• relative humidity of air –> below 75%
• moisture levels should be <10% (usually rises in tropical areas)
• fungal growth in feeds will also increase the moisture content in feeds –> increased moisture, increased fungal growth

Question 15

How to reduce the deterioration of feed with regards to temperature?

Answer 15

• temperatures > 25 degrees Celcius
• if temperature higher than 25 Celcius, rates of deterioration and loss may rapidly increase
• affect the rate of loss of heat liable vitamins & nutrients
• fungal growth and insect infestation will increase the temperature
• lipids can be broken down into free fatty acids –> causing rancidity

Question 16

How should vitamins and minerals be stored?

Answer 16

• kept either in the manufacturer’s container or in airtight lightproof containers
• should be kept in refrigeration
• vitamin C (ascorbic acid) –> easily damaged by heat, light and humidity

Question 17

How should light and heat-sensitive materials be stored (e.g. fish oils)?

Answer 17

• stored in dark containers

Question 18

How should wet feeds be stored?

Answer 18

• in freezers

- frozen to prevent deterioration of the quality of the nutrients

Question 19

How should dry feeds be stored?

Answer 19

• secure building/room/enclosed space that is protected from rain
• ventilation points (windows not recommended)
• drier and cooler the store can be kept, the better the quality of feed will be