Week 4

Question 1

egg production history

Answer 1

1900s:
chicken was a luxury
eggs were main protein source
80-150 eggs per year

1920-30s:
improved breeding, management and demand for more intensive farming
hens laid 250 eggs per year

1930-50s: semi intensive commercial egg production (100-1000s hens) housed in sheds with access to yards

1950s onwards
intensive production introduced
commerical farms can house 500, 000 hens
1980s egg boards deregulated and egg production is now a free market
2000s hens lay 371 eggs/year

Question 2

free range eggs advantages

Answer 2

access to outdoors and ability to roam freely

interact socially

natural behaviours such as nesting, foraging for food

better bone strength due to better movement and activity

Question 3

free range egg disadvantages

Answer 3

greater exposure to predators

harder biosecurity for farmers due to outside pathogens

increased likihiood of social stress and cannibalism

a greater occurrence of manure pron illness and parasites

increased need for antibiotics to treat sick hens

Question 4

Cage eggs

Answer 4

• Automated feeding & watering, ventilations, lighting manure and egg collection - Climate control kept at 23C
• Produce eggs at low cost

Question 5

cage egg benefits

Answer 5

hens rarely get sick

avoid injury from infighting as small groups allow them to establish stable pecking order

lower carbon footprint

less need to veterinary medications such as antibiotics

protected from predators
produce more eggs and cleaner eggs – cheaper

fewer occurrences of manure born illness, parasites and other exotic diseases

Question 6

cage egg disadvantges

Answer 6

reduced social interaction

unable to roam freely

unable to practice natural behaviours

generally unable to perch, lower bone strength

Question 7

barn laid eggs advantages

Answer 7

protected from treat

more free inside shed

increased social interaction with larger flocks

furnishings within barn allow hens to practice natural behaviours such as nesting, perching and dust bathing

Question 8

barn laid disadvantages

Answer 8

greater occurrence of manure born illness

greater difficulty identifying and treating sick hens

higher likelihood of injury due to feather pecking and infighting

less stable pecking order due to the size of the flock

Question 9

Free range chicken have poorer productivity, higher mortality and compromised health & welfare compared to conventional farms

Question 10

Nutrition from eggs

Answer 10

• Source of protein 6.4g
• Rich in vitamin B2, B12, D, A, E
• Source of iodine and iron, calcium and zinc

Question 11

Nutritional benefit form egg white

Answer 11

• Antimicrobial activity
• Thiamin transport
• Inhibiting cholesterol absorption

Question 12

Nutritional benefit from egg yolks

Answer 12

• Contains liposoluble glycoproteins called lipovitellin
• Shown to prevent atherosclerosis, a condition by the buildup of cholesterol in
  the wall of blood vessels

Question 13

Egg formation - physical composition on the avian egg

Answer 13

• Self-contained raw ingredients for the formation of a check
• If fertilized, embryo floats on upper surface of yolk
• Shell of a chicken is porous, and the large end of the egg contains more pores
• Concentric rings of yold - not seen if hen has received a uniform diet - reflects consumption of foods with different pigments
• Albumen surrounds yolk and enclosed by two that are fused except at blunt end (air space)
• 32-35% yolk, 52-58% albumen, 9-14% shell
• 33% lipid, 17% protein and small amounts of mineral, vitamins and carbohydrates

Question 14

The ovary

Answer 14

• Has only one functional ovary
• At the time of hatching, the female chick has up to 4000 tiny ova
  (reproductive cells), some of which full-sized yolks may develop when
  hen is mature
• Each yolk (ovum) is enclosed in a thin-walled sac of follicle attached to
  the ovary.
• This sac is richly supplied with blood

Question 15

The oviduct

Answer 15

• The mature yolk is released when the sac ruptures and is received by the funnel on the left oviduct
• The left oviduct is coiled or folded tube
• It is divided into five distinct sections

Question 16

The defense mechanism of the eggs & quality assessment

Answer 16

The outsides of egg shells are not sterile and different microorganisms are associated with the surface of egg shells. A compromised barrier allows microbes on eggshell to enter eggs
Poultry frequently carry Salmonella & it may become part of the bacterial flora of the egg shell during ovulation

Question 17

Mechanical barrier

Answer 17

• The crystalline eggshell (porous to allow gas) and the waxy hydrophobic, proteinaceous layer (cuticle) act as a barrier to liquid.
• The cuticle does not harden immediately, and washing can damage the layer making it permeable
• Cooling of the eggs post-lay creates a vacuum that can pull air & microbes through the pores
• Enzymes released by some bacteria (Pseudomonas or Salmonella) are able to damage the cuticle.

Question 18

Biological barriers

Answer 18

• Contents of eggs are generally sterile - some vertical contamination form reproductive tract and after lay
• Egg white contains lysozyme, avidin, protease inhibitors, conalbumin-inhibitory effects on microorganisms
• High pH -9.3 makes it difficult from gram-positive bacteria and some yeasts to grow

Question 19

Grading

Answer 19

The Food Standards Australia New Zealand (FSANZ) code stipulates cracked, and visually dirty eggs are unable to be sold to retailers or caterers for direct human consumption due to risk of infection
- Automatic candling technology (light spectrum analysis of the inside of the egg) detects internal defects
- Quality control on the grading floor also involves checking for tiny cracks that might not be visible to the human eye and measuring the height of the albumen (egg white) and shell thickness.
- Automatic acoustic crack detectors contain probes that gently tap the eggs at very fast speeds as they pass through the machine. If there is a crack in the eggshell, no matter how small, the tapping energy will be absorbed, resulting in a duller sound

Question 20

Albumin

Answer 20

Albumin
- The height is an indicator of membrane integrity and structure of proteins
- As egg ages the proteins denature and can no longer retain moisture egg spreads
out and albumin height decreases
- Yolk ratio decreases as egg ages
- Haugh unit is a measure of eqq quality based on the height of its egg white - If pH of albumen becomes more alkaline it means microbial growth

Question 21

Yolk colour

Answer 21

Fades during storage pigments become diluted by mouser passing through vitelline membrane
- Ass egg ages yolk width increases as yolk taken in moisture, yolk height decreases, and yolk weight increases

Question 22

Environmental factors affecting egg quality

Answer 22

Heat stress
- reduced egg quality
- greater capacity for Salmonella contamination (vertical contamination)
Environment
- A contaminated environment, increased fouling of eggs, broken eggs
Animal behavior
- feather pecking, cannibalism, egg consumption
Diet quality
- protein quality, digestibility of feed, adequate level of calcium

Question 23

Over time

Answer 23

• Egg weight decrease
• Yolk weight increases
• Albumen weight decreases - Albumen pH increases
• Albumen height decreases

Question 24

Endemic disease

Answer 24

• Infection bronchitis virus, mycoplasma etc

Question 25

Zoonotic

Answer 25

• Duck virus hepatitis - Influenza A etc.

Question 26

Contamination

Answer 26

Intact eggs can become contaminated with salmonella as a result of infections of the
reproductive tissues of the laying hens but also by penetration through the shell
- Evidence of contamination is only picked up by candling

Question 27

Methods to safeguard production and the supply chain

Answer 27

• Improving vaccination programs and manipulating the diet / environment to continue producing safe, high-quality food is an imperative
• Develop resistant strains through genetic selection
• Better legislation to improve safety of eggs and egg products
• pasteurization of egg product
• Improved consumer awareness

Question 28

Housing systems -

Answer 28

• Regardless of the type of production system, all Australian egg farms must meet animal welfare and food safety codes, including undergoing third-party audits however, the debate on hen welfare often focuses on the housing system, and there are concerns about the welfare of hens in conventional cages
• Consumer perception and retailer purchasing power is driving welfare considerations and this does not necessarily encompass health and other issues
• Climate conditions and diseases: Adverse climate conditions and avian influenza are a concurrent threat to the free-range egg industry in Australia. Heat stress, cannibalism, and grass impaction are some of the challenges faced by free-range egg producers.

Question 29

biosecurity

Answer 29

poultry

introduction of new birds
tranfers between production areas
dead bird disposal

farm

inadequate hygiene

other animals

wild birds
insects
rodants
feral/domestic animals

feed contamination
transmission via air/wind

equipment
inadequate sterilisation, housing, packaging, vaccines
vehicles not decontaminated