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What are the animal welfare issues associated with depopulation and slaughter of spent hens?

Spent hens are commercial egg-laying hens that are removed from the egg production system due to reduced egg production and egg quality. In commercial egg-laying hens, egg production falls at around 72 weeks of age to well below their peak rate. For egg farmers, these hens are no longer profitable and hens are, therefore, removed from the system to be replaced by younger hens. This process of removal of spent hens from cage, barn or free-range egg production systems is known as depopulation.

Layer hen

What are the main methods of spent hen depopulation?

The two main methods of depopulation of spent hens in Australia are on-farm euthanasia by carbon dioxide gassing, and off-farm slaughter, where hens are caught, crated, and transported to abattoirs for killing and further processing [1].

The animal welfare issues with depopulation include [2, 3, 4]:

  • Layer hens are caught and handled at depopulation. Egg-laying hens are known to have weakened bones due to calcium deficiency. During this handling process, chances of bruising, injuries and fractures are extremely high, especially if conducted by untrained personnel.
  • The catching and handling process induces fear and may cause pain.
  • During transport, changes in the environment (e.g. temperature, noise, surroundings) and lack of food and water induces stress.
  • Where carbon dioxide gas is used for on-farm euthanasia, hens find the gas aversive to inhale. Smothering may occur if hens are not dead before placing more hens into the gas container used for euthanasia.

Do we eat layer hens?

Layer hens are not used for meat because they are a different breed to meat chickens and have a much lower meat yield. Instead, hens have been bred to produce large numbers of eggs. The meat from spent hens is less desirable for human consumption due to a difference in taste and texture, and so will usually only be processed into lower-quality food products e.g. soups and stocks, or pet food.

How can I consume eggs responsibly?

Moving away from systems where hens are housed in cages brings about benefits to spent hen welfare. Hens in cage-free systems experience fewer fractures at depopulation than hens in battery cages [2]. There is also a reduced incidence of osteoporosis in cage-free hens, meaning minimised risks of injuries and fractures during handling.

The RSPCA opposes the housing of layer hens in battery cages because hens in cages are not able to exhibit normal behaviours like perching, dust bathing, foraging and laying eggs in a nest. Hens suffer greatly in battery cages. By opting to purchase cage-free or free-range eggs, you can be sure that eggs are sourced from systems that aim to meet the bird’s behavioural needs.

To learn more about layer hens, visit our website.

For more information on the RSPCA Approved Farming Scheme standards for layer hens, visit here.

References

[1] Poultry Hub (2019) On Farm euthanasia of spent layer hens (accessed Sep 5, 2019)

[2] Newberry R et al (1999) Management of spent hens. Journal of applied animal welfare science 2(1): 13-29. doi:10.1207/s15327604jaws0201_2

[3] Poultry Hub (2019) Chicken Egg (Layer) Industry (accessed Sep 4, 2019)

[4] Thaxton Y et al (2016) Symposium: Animal welfare challenges for today and tomorrow. Poultry Science 95(9): 2198-2207. doi:10.3382/ps/pew099

Also Read

Updated on September 16, 2019
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https://kb.rspca.org.au/knowledge-base/what-are-the-animal-welfare-issues-associated-with-depopulation-and-slaughter-of-spent-hens/

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