Painful fractures: Large eggs push small hens to the breaking point,
study finds

Date:
September 2, 2021
Source:
University of Copenhagen - The Faculty of Health and Medical
Sciences
Summary:
The majority of laying hens in Denmark suffer from keel bone
fractures, a new study reveals. The fractures appear to be the
result of disproportionately large eggs, which push the hen's body
to the breaking point.



FULL STORY ==========================================================================
The majority of laying hens in Denmark suffer from keel bone fractures,
a new study conducted at the University of Copenhagen reveals. The
fractures appear to be the result of disproportionately large eggs,
which push the hen's body to the breaking point. The researchers behind
the new study call it a huge global problem for animal welfare.


==========================================================================
The indigenous hen lays around 20 eggs a year, whereas a modern laying
hen produces around 320 eggs a year. In other words, being a hen bred for
the food industry is a full-time job. In fact, the egg laying appears
to be such a strain on Danish as well as foreign hens that it results
in bone fractures.

New research from the University of Copenhagen shows that too large eggs
in too small hens affect the Danish animal welfare. In the largest study
of its kind, the researchers have shown that around 85 per cent of Danish laying hens suffer from keel bone fractures. This is, to all appearances, because the large eggs pressure their bodies from within.

"We knew there was a problem, but we certainly did not expect it to apply
to almost all laying hens in the country. These animals suffer, both
when the fracture occurs and afterwards, so we are dealing with a huge
animal welfare problem here," says Assistant Professor Ida Tho/fner from
the Department of Veterinary and Animal Sciences. She explains that the
problem is not only widespread among Danish hens, but is of global extent.

A painful problem among both organic, battery, barn and free-range hens Together with Professor Jens Peter Christensen, she has examined almost
4,800 hens in 40 different flocks for keel bone fractures and found
fractures in almost 4,100 of them.



==========================================================================
"We see these types of fractures in all production systems. That is,
regardless of whether the hens are kept in cages, or they are organic
or barn or free- range hens. In other words, it is a widespread problem
in all parts of the industry," says Jens Peter Christensen.

He explains that fractures usually occur at the tip of the keel bone,
and the nature of these fractures suggests that the hen's body is simply
under too much strain due to too large eggs.

"If you have ever tried to fracture a bone, you know that it hurts. A
cast and rest is not an option for laying hens, whose fractures probably
hurt a lot and take a long time to heal," he says.

Small hens, large eggs The researchers also tried to identify the exact
cause for the many fractured bones by pointing out the risk factors
in play.

"Generally, we can see that the larger the eggs and the smaller the
hens, the greater the problem. Their bodies are simply under too much
strain because they are bred to be small and to lay a lot of large
eggs. At the same time, we know that the keel bone takes a long time
to mature. Unfortunately, it takes some generations of hen breeding to
solve that problem," says Jens Peter Christensen.

However, Danish farmers may be able to reduce the problem quickly and
without having to involve the breeding companies.

"The earlier these hens enter into production, the larger the problem
is. We are fairly convinced that you could postpone egg laying for a
couple of weeks until the hens are more robust and the keel bone is
more resilient to fracturing without losing money, because the hens
will simply lay eggs for a longer time if you follow this strategy,"
Ida Tho/fner explains.

The researchers now hope to attract funding for an intervention project
in order to study the effect of various measures on solving the problem
and increasing the animal welfare.

========================================================================== Story Source: Materials provided by University_of_Copenhagen_-_The_Faculty_of_Health_and
Medical_Sciences. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Ida C. N. Tho/fner, Jan Dahl, Jens Peter Christensen. Keel bone
fractures
in Danish laying hens: Prevalence and risk factors. PLOS ONE,
2021; 16 (8): e0256105 DOI: 10.1371/journal.pone.0256105 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/09/210902124929.htm

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