How do they produce eggs?

How do they produce eggs?

HFG senior nutritionist Rose Carr investigates a protein staple.

It’s estimated that in 2010 we had around 3.3 million laying hens in New Zealand producing around one billion eggs. On average, New Zealanders consume about 230 eggs each in one year — that’s 4.4 eggs each week.

How are eggs farmed?

The majority of eggs produced are from conventional cage production systems (88 per cent) with the rest produced in free range (10.6 per cent) or barn (1.4 per cent) production systems.

Free-range hens are able to roam free outdoors and they also have indoor shelter for night and inclement weather conditions. Commercial free-range farms can have a few hundred hens to thousands of hens. The larger farms have hens in a number of flocks. The sheds are fitted with nest boxes and perches and the hens have access to the outdoors through pop-holes in the walls. Chickens’ ancestors are from the jungle and they need access to cover outdoors from shrubs, trees or built cover, so they feel safe from predators.

How do I know eggs are free range?

Look for ‘free range’ on the pack. Some supermarkets also label their shelves ‘free range’.

How do I know eggs are barn raised?

Look for the terms ‘barn eggs’, ‘uncaged’ or ‘cage free’ on packs.

Barn hens live in a barn or shed where they are able to roam. The shed may or may not have vertical levels and the floor may be based on litter or other material such as slats or wire mesh. Barn hens don’t have access to the outdoors.

How do I know eggs are cage raised?

Some packs will tell you they contain eggs from caged hens, but for many you will only know by default. If the pack does not state the hens were raised in a free-range, barn or uncaged environment — you may see the words ‘farm fresh’ — then the eggs will be from a caged hen.

Cage or battery hens are housed in cages within a shed. The cages must provide a minimum of 500cm² per hen (that’s about 22.4cm x 22.4cm).


In addition to the different housing systems, we can purchase eggs from organic farms which exclude the use of synthetic fertilisers and pesticides. Organic eggs make up around one per cent of egg sales. Biogro, Agriquality or Demeter are recognised organic certification marks which tell us the food has been independently audited and certified as organic.

SPCA blue tick

The Blue Tick is a national certification programme run by the SPCA that identifies animal food products produced in a manner guaranteed by the SPCA to be cruelty-free.

The SPCA has specific standards set out for free-range and barn eggs. Producers qualify for certification by meeting the SPCA’s welfare standards. They are then audited on a regular basis and spot audits may also be done at any time. In return for accreditation, the producers are levied on their egg sales and these funds are used to administer and promote the accreditation system as well as undertake the audits.

The SPCA has, as its basis, the philosophy that all animals equally deserve our compassionate consideration, whether they are a dog tied up and neglected in a backyard or a possum chewing through our native forests.

From chicken… to egg

Zeagold, one of New Zealand’s largest egg producers, raises laying hens in both conventional cage and free-range systems. In their farms, young chicks are raised to around 19 weeks old before they start laying eggs. At their large Waikouaiti processing operation outside of Dunedin, the eggs roll from the laying sheds onto a conveyer belt which takes them to a centralised grading room. The eggs travel through a ‘candling’ booth, a darkened area where lights shine up through the eggs, highlighting any cracks or blood spots. Imperfect eggs are removed by the grading machine while the remainder are electronically weighed, graded by weight and packed into cartons. While smaller farms are less automated, the process from hen to pack is quite similar.

The price of eggs

The price of eggs increases with the size or grade of the eggs, and generally larger packs with more eggs in them will be cheaper, per egg, than smaller packs. However, the type of production system has the most significant impact on the price of eggs in our supermarkets.

For example, from three Auckland supermarkets, we found:

  • Cage eggs ranged from $0.20 cents to $0.42 cents each
  • Barn eggs ranged from $0.49 cents to $0.71 cents each
  • Free-range eggs ranged from $0.40 cents to $1.25 each
  • Free-range organic eggs ranged from $0.85 cents to $1.03 each

Compared to other high-protein foods, standard cage eggs can provide the most economical source of protein at $0.38 cents for 10g protein versus $0.56 cents per 10g from lean beef mince. At the other end of the scale, the most expensive free range eggs can be up to $1.53 for 10g of protein compared to eye fillet steak at $1.73 for 10g.

What the grade numbers mean

  • 5 — Medium: 44g minimum per egg, 528g minimum per dozen
  • Mixed grade eggs: Average 48.5g per egg, 582g minimum per dozen
  • 6 — Standard: 53g minimum per egg, 636g minimum per dozen
  • 7 — Large: 62g minimum per egg, 744g minimum per dozen
  • 8 — Jumbo: 68g minimum per egg, 816g minimum per dozen

The future  from cages to colony or enriched-cage farming

Cage-raised hens do provide us with cheaper eggs. But keeping hens in such cramped conditions is abhorrent to animal welfare groups and to many consumers.

The next step away from conventional cage farming is known as the colony or enriched-cage system which provides the hens with more space than conventional cages. These larger cages include areas for perching, laying and scratching so the hens can move around, stand erect and extend their wings.

Phasing out conventional cage farming and moving to colony or enriched cages is the key recommendation in the draft Code for Animal Welfare — Layer Hens released for consultation by the Ministry of Agriculture and Forestry (MAF) in February. In Europe, a ban on battery hens comes into effect on 1 January 2012 and the colony system is being adopted.

Did you know?

  • Brown eggs come from brown-feathered hens and white eggs from white-feathered hens. Shell colour varies with the breed of hen and is not related to quality, nutrients, flavour or cooking characteristics.
  • A hen requires between 24 and 26 hours to produce an egg.
  • The size of eggs a hen lays increases as she gets older.
  • To find out the age of your eggs, check the ‘best before’ date on the pack: the New Zealand industry standard is to date the eggs on the day of lay plus 35 days.
  • To test if an egg is fresh, place it in a bowl or glass of water. If the egg lies on its side on the bottom, it’s very fresh. If the egg stands up and bobs on the bottom, it isn’t quite as fresh but is still usable. If the egg floats on the surface, it should be discarded.
Author: Rose Carr

Healthy Food Guide

First published: Oct 2011

2017-12-05 15:34:26

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