Lecture 11 Week 6 - Poultry

Question 1

How long does a chicken live for?

Answer 1

10-15 years

Question 2

What type of breeders are chickens? How have humans exploited this?

Answer 2

They’re SEASONAL breeders, genetic selection has allowed them to breed all year round.

Question 3

What is a Rhode Island chicken an example?

What is the offspring of a RIR male & RIW female?

Answer 3

A cross between many different chicken breeds. Can be red or white.
White male & brown female - males are euthanised.

Question 4

Why did egg consumption skyrocket in the early 2000s?

Answer 4

Realised that the cholesterol in eggs was not actually that bad for you.

Question 5

What % of eggs does Australia export?

Answer 5

5% - therefore we mostly consume domestic eggs.

Question 6

What are 4 reasons why monogastric meat consumption is increasing?

Answer 6

1. Relatively cheap to produce
2. Accessible
3. Considered healthy
4. Growing population = need more food

Question 7

Is there in an increase in free range egg consumption compared to cage eggs?

Answer 7

a greater percentage of eggs bought are FR.

Question 8

What are 5 trends seen in the egg industry?

Answer 8

1. Increase in the number of pullet & layers in Australia
2. Increase in number of eggs being produced, therefore increase in value of the industry
3. Increase in the price of specialty eggs - cage, FR & barn-laid all stayed the same price over time
4. The number of eggs we are eating has increased
5. Genetic progress - the average number of eggs a chicken can lay has increased (an extra 2.3 eggs/hen/year)
   * ** Hens ‘persist’ in laying for longer. They can lay and lay and lay for longer periods of time before starting to reduce

Question 9

What differentiates an egg laying chicken to a meat producing chicken?

Answer 9

Egg laying = smaller, more viable

Meat producing = larger with bigger breast muscles

Question 10

Why is an egg a nutritionally complete food? Can it be supplemented with anything else?

Answer 10

It contains proteins, fats, vitamins & minerals. Can make it more complete by supplementing it with selenium, omega-3 or vitamin E —> ‘designer eggs’

Question 11

What are some ‘supposed’ disadvantages of FR eggs?

Answer 11

1. Increased mortality
2. Poorer welfare
3. Lower productivity - diet isn’t as controlled

Question 12

What are 2 ways the weight of an egg can be altered?

Answer 12

1. Adding methionine into the feed

2. Making it darker so hens hold off on layer eggs until they are older & bigger

Question 13

Which part of the eggs takes the longest to produce? How many days does it take?

Answer 13

Yolk - 9 days

Question 14

How long does it take to form an egg?

Answer 14

25 hours

Question 15

What comprises the yolk? What is the name of the thin membrane surrounding it?

Answer 15

Lipids & proteins (& some antibodies). Most nutrition comes from the yolk. Vitelline membrane.

Question 16

How many membranes enclose the albumen?

Answer 16

2 - fused except at air space.

Question 17

What is the chalaza?

Answer 17

2 spirally proteins (1 at each end of egg) that help to stabilise the yolk.

Question 18

What 4 parts comprise the egg shell?

Answer 18

Mammillary layer, palisade, pores, cuticle

Question 19

What are 4 consumer expectations to do with eggs?

Answer 19

1. Shell = uniform colour, free from defects
2. Yolk = uniform colour, free from blood spots
3. Albumen - stays together when egg is cracked on flat surface
4. Neutral taste
   * ** Overall, homogenous appearance

Question 20

What 2 anti-spoilage mechanisms does an egg have?

Answer 20

1. Physical attributes e.g. hydrophobic, proteinaceous layer (cuticle) which overlies the eggshell and pores, also a porous shell that allows gas exchange
2. Chemical e.g. albumen

Question 21

What are external quality indicators of eggs?

Answer 21

Basically all to do with the shell:

1. Shell defects e.g. cracks - ‘Candled’ to detect these
2. Egg shell weight as part of total weight
3. Visible shell defects
4. Eggshell thickness (using calipers)

Question 22

What are internal quality indicators of eggs?

Answer 22

1. pH (9.3 inhibits bacterial growth)
2. Albumen height (indicator of membrane integrity and structure of proteins) - as egg ages proteins denature & also amount of water absorbed decreases
3. Albumin pH
4. Albumin:Yolk ration (decreases with age)
5. Haugh unit (freshness measure)
6. Yolk size (ratio compared to rest of egg increases) & colour (decreases with storage)

Question 23

What 4 environmental factors can affect egg quality?

Answer 23

1. Heat stressed hens – reduced egg quality
2. Environmental – contaminated environment
3. Animal behaviour – feather pecking, cannabilism, egg consumption
4. Diet quality: protein quality, digestibility of feed, adequate level of calcium

Question 24

What is one way that egg quality can be maintained after purchase?

Answer 24

Refrigerate them! High temperature 25°C versus 5°C increases the rate of egg degradation over time.

Question 25

What are 5 current challenges to egg industry and food security

Answer 25

1. Disease e.g. salmonella
2. Health scares e.g. bird flu
3. Competition for feed ingredients - a lot of land is cleared to grow animal feed
4. Animal welfare
5. Pollution - excretion of phosphorous & nitrogen. Where is this waste going?