Throughout the world, male chicks from layer breeds are killed just after hatching, as they are not profitable as regards the production of meat. The Dutch and European parliaments have insisted on research into possible alternatives to the killing of day-old chicks. In the present study we have investigated Dutch public opinion on the acceptability of these alternatives by means of discussions in so- called focus groups and via a public survey through computer-aided personal interviews (CAPI). To inform the participants about the subject, a film was made to explain the current practice and introduce a number of technological alternatives that would prevent development of male embryos, as well as the possibility of creating a ‘dual-purpose chicken’ that would allow male chicks to be used for meat production. The topics addressed in the study included the willingness of participants to pay a premium for eggs and chicken meat, were it necessary to prevent killing of male chicks. Focus-group discussions showed that many participants were unaware of the current practice of killing male chicks, and were shocked by this practice. However, once informed, the participants seemed able to take various considerations into account and rank the alternatives. The alternatives ‘looking into the fresh egg (to determine sex of the egg and not incubate male eggs)’, and ‘dual-purpose chickens’ scored best out of all the possible alternatives, and higher than maintaining the current practice. ‘Influencing the laying hens such that they produce fewer male eggs’ scored the same as maintaining the current practice. The use of ‘genetic modification to facilitate looking into the fresh egg’ scored only slightly lower than maintaining the current practice. Alternatives whereby developing male embryos die, or are killed, scored lower than maintaining the current practice.

1. Killing one-day-old male chicks, do we have alternatives?
Opinions of ‘the public’ about alternatives to the killing of one-day-old chicks
Research for the Ministry of Agriculture, Nature Management and Food Quality
October 2008
Summary and conclusions
F. Leenstra1, G. Munnichs2, V. Beekman3, E. van den Heuvel-Vromans2, L. Aramyan3 en H. Woelders1.
Animal Sciences Group, Wageningen UR, PO Box 65, 8200 AB Lelystad
Rathenau Institute, The Hague
3
Agricultural Economic Institute (LEI), Wageningen UR, The Hague
1
2
Design and working method:
H. Hopster (Animal Sciences Group, Wageningen UR)
Advisory group:
G. Albers (Hendrix Genetics BV), A. Butijn (NOP Kring Kuikenbroeders), M. de Jong (Animal Protection), P.Bours
and E. Ganzevoort (LNV) participated in the advisory group.
Film production:
CB-Media, C. Brinkhuizen and L. van der Pol.
The results of the discussions in the focus groups and of the public inquiry have been discussed during a
workshop with F. Brom (Rathenau), T. de Cock Buning (VU), F. Stafleu (UU), S. Swart (RUG) and C. van der Weele
(WUR). Notions from that discussion were integrated into this report.

2. Killing one-day-old chicks, do we have alternatives?
Opinions of ‘the public’ about alternatives to the killing of one-day-old chicks
Background and definition of the problem
The commercial poultry industry is strongly specialised throughout the world. There are breeds that are
specialised in laying eggs, others in producing meat. Because the roosters of laying breeds do not produce eggs
and are not profitable in producing meat, they are killed when one day old. This happens throughout the world
and is done with ‘common’ as well as with organic poultry. This specialisation and with this the practice of killing
roosters have already existed for approximately 50 years. In the Netherlands 30 million hens are born annually
which are used for the production of eggs. Because as many males are born, 30 millions male chicks are killed
annually when they are one day old. This mass killing raises discussions. The Dutch parliament has insisted on
research into alternatives, which will prevent that male chicks are born. In an earlier stage the technological
aspects were described in the report ‘Alternatives to killing one-day-old chicks’, which was presented to the
parliament in March 20071.
Before the government invests in a possible direction towards a solution, the Minister of Agriculture has ordered
a research into what solutions are considered societally acceptable. The results of the research into the public
opinions about the current practice and possible alternatives are described in this report.
Aim and working method
To gain insight into the opinions about alternatives to killing the male chicks, intensive discussions have taken
place with small groups of people (focus groups). Moreover, a public inquiry was instituted. To inform the
participants about current practices and alternatives, a documentary film was made. While the public inquiry is
a representative presentation of people’s opinions, the focus groups can be used to provide an insight into the
thoughts and motivations behind these opinions. There were 6 focus groups, with 7 or 8 participants each. The
most important criterion for recruiting the participants was sex and living environment (town and countryside).
The focus group study was done before the public inquiry, because the former’s results were used to formulate
the questions and to examine what information the participants of the inquiry need to form an opinion. The public
inquiry was carried out through the internet. Twelve-hundred of the questionnaires were completed, these were
used for further analysis.
The results of the focus group research and of the public inquiry were discussed during a workshop with ethicists
and stakeholders to come to a better interpretation of the results.
How to read this report
In this text the results of the research in the focus groups and the public inquiry and our conclusions have been
summarised. Separate boxes describe the current practice and possible alternatives.
The complete analysis of the discussions in the focus groups and of the public inquiry can be found in ASG-report
142 (in Dutch). The film that was used for this research can be found on www.wur.asg.nl
Results
Emotions, the plain truth and differentiation
The participants were informed about the killing of male chicks by the film and were presented with eight
alternatives, which should prevent that male chicks are born. These eight alternatives were subdivided into
3 categories: ‘looking into the egg’, ‘changing the hen’ and ‘genetic modification’. These alternatives were
completed with ‘the combination chicken’ a chicken breed suitable for both egg and meat production. For a more
extensive description see the adjoining box.
1
Alternatives to the killing of one-day-old chicks, H. Woelders et al., 2007.
2

3. In the focus groups people were shocked at first at the
information about killing of male chicks. However, they
did not stick to this initial response, and were able to
discuss a broad variety of considerations. The entire
story was considered complicated, particularly when
they had to give an order of preference of the different
alternatives (“my brains start to crack”). They often
wanted more information, for example whether the
alternatives were feasible, or the exact impact on the
chicken. However, because the alternatives are in an
experimental stage, such information is not available
yet.
The inquiry showed that 58% of the people did not know
that roosters of laying breeds are killed right after birth.
Half the people felt uncomfortable about the killing, while
another 36% thought it bad or really bad. Fifty-eight
percent of the respondents considered it useful to look
for alternatives.
Three technological alternatives were, in first instance,
considered reasonably societally acceptable:
1. Examining a sample of a freshly-laid egg and not
hatching the males
2. Influencing the chicken by environmental factors, due
to which fewer male eggs are laid
3. Influencing the chicken by genetic modification such
that eggs can be recognised as to sex
No clear ‘best’ option
After the participants determined their preferences
within the three categories, they were provided with their
preference per category plus two other possibilities:
‘combination chicken, where the males are used
for meat production’ and ‘accepting the killing as is
currently done’. The respondents were asked to order
their preferences within these five possibilities. As to the
first preference there was a clear top-five:
Possible alternatives to killing male chicks
In the study we have described a number of in principle
possible alternatives. Only the alternative ‘looking into the
egg, late embryo’ has been successfully carried out in
the laboratory, but not on a practical scale yet. The other
options are all in an experimental stage. Summarised the
following alternatives apply:
Looking into the egg
1. Examining a sample of a freshly laid egg and not
hatching the male eggs
2. Examining a sample of an early embryo and destroying
the male embryos
3. Examining a late embryo and destroying the male
embryos
Changing the hen
4. Influencing the hen by environmental factors, due to
which fewer male eggs are laid
5. Crossing the parents in such a way that male embryos
are not viable
Genetic modification
6. Influencing the chicken by genetic modification such
that eggs can be recognised as to sex (for example
by a photogenic gene of a firefly) and not hatching the
eggs with a male embryo
7. Influencing the chicken by genetic modification such
that male embryos become female chickens
8. Influencing the chicken by genetic modification such
that the male embryos die early
In the research these technological alternatives were
complemented with the options:
9. Accepting the killing of one-day-old chicks as is done
nowadays
10. Less-specialised chickens, so that the males can be
used for meat production (‘combination chicken’)
The technological alternatives have a great impact on
the level of the hatcheries, but do not really change the
production of eggs and broiler meat. The combination
chicken does, as the hens are bigger than the current
laying hens and produce fewer eggs and the males need
more time to reach the desired weight than the current
broilers.
Alternatives ticked as first preferences
Looking into the fresh egg and not hatching the males
Combination chicken
Influencing the chicken by environmental factors,
due to which fewer eggs with a male embryo are laid
Accepting the killing as it currently is done
Adapting the chicken by genetic modification such that eggs can be
recognised as to sex
% respondents
25%
24%
14%
14%
10%
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4. Because the respondents had indicated the order of their preferences, we could take account of this order by
weighing factors. Regardless of the way of weighing, ‘looking into the fresh egg and not hatching the males’ and
‘combination chicken’ were almost equal and had a higher score than all other options. ‘Accepting the killing’
and ‘influencing the chicken by environmental factors, due to which fewer male eggs are produced’ ended at
a somewhat lower, almost equal score. ‘Adapting the chicken by genetic modification such that eggs can be
recognised as to sex’ ended fifth. All other possibilities had clearly lower scores.
Arguments for choices
In the public inquiry we asked the respondents to indicate which reasons were important for their choices and
considerations. To this end they were provided with seven notions, which had been mentioned frequently in the
focus groups. These were:
‘animal-friendliness’
‘feasibility’
‘naturalness’
‘ food security’
‘males used as animal feed’
‘moral considerations’
‘costs’
For each notion an indication could be given as to importance in making choices. Animal friendliness scored high,
followed by naturalness and food security.
Animal friendliness was an often-mentioned argument in the focus groups. ‘Humane’ and ‘animal friendly’ were
used indiscriminately. Killing the one-day-old chicks and destroying male embryos late in the incubation process
were considered animal unfriendly; ‘the combination chicken’, ‘influencing the sex by adapting the environmental
factors of the hen’ and ‘looking into the egg and not hatching the males’ were regarded as animal friendly.
According to the participants in the focus groups naturalness means intervention with ‘nature’ or ‘animal’ as little
as possible. This argument was used both to plea in favour of or against particular options. Many participants
considered influencing environmental factors a natural method, whereas genetic modification was regarded as
‘unnatural’. The meaning of the term ‘naturalness’ is not the same to everyone, however. The participants have
different opinions about how drastic a certain method is. One of the respondents, for example, indicated that
influencing the environmental factors was a further manipulation of the nature, and those in favour of genetic
modification differentiated between the various GM-alternatives depending on the extent of naturalness of the
intervention.
Also the risks for human and animal safety and moral considerations play a role, particularly in the discussion
about genetic modification. For a number of participants the GM-methods were no option. Statements as ‘one
bridge too far’ or ‘unethical’ indicate that moral boundaries are exceeded. These statements were, for that matter,
mentioned together with the ‘unnatural’ character of genetic modification (“nothing is natural here”). This suggests
that moral considerations are in line with the argument of (un)naturalness.
More practical considerations, such as costs and feasibility of the method, price of eggs and meat, manure
issues and the use of one-day-old chicks also play an
important role in the focus groups. The higher costs of
eggs (and products with eggs) and the manure issues
Current method in killing the one-day-old
chicks
were important reasons for some participants to be
against the combination chicken. Other participants
The killing of one-day-old chicks in the Netherlands
considered ‘looking into the egg’ a complicated
usually happens automatically by CO2. The chicks
method and GM a quick and efficient method. The
go via a conveyer belt to a room with a high
concentration of CO2, which causes the chicks to
use of one-day-old chicks was an argument in favour
become unconscious after a few seconds. They die
of maintaining the current situation. How often these
after several minutes. The dead chicks are used
arguments were mentioned, however, they were not
as feed for zoo animals and (predator) animals of
always decisive. The fact that sex determination in the
private people. Research has defined which mix of
air and which concentration of CO2 lead to a quick
late embryo can be realised in the short term, and can
unconsciousness and death.
thus be considered the most feasible alternative, does
One alternative to killing by CO2 is killing by a
not offset the aversion to killing the embryo. On the
chopper, in which the chicks are killed within
other hand the higher costs of eggs and meat with the
tenths of seconds. This very quick killing method
is preferable from an animal welfare viewpoint; the
combination chicken did not prevent some participants
disadvantage, however, is that chopping rouses
from mentioning it as first or second preference. Lastly,
aversion and that the chopped chicks have less
it should be mentioned that a number of participants
value than chicks killed by gas.
have the opinion that the laying hen does not have a
bright life. For some of them this was a reason not to
think about these issues a lot. Others had the opinion
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5. that the consumer should be far more aware of these
practices. The current practice for keeping laying hens
was, however, also an argument against the combination
chicken.
Costs and willingness to pay
We have also asked whether one is willing to pay
more for eggs and broiler meat. This willingness was
more or less linked to the alternative one had chosen.
Approximately 10-15% of the people were not willing
to pay more, 50-60% of the people declared to be
willing to pay 5 to 10 eurocents extra for an egg, if
their preference was applied and 15-30% said that they
would pay double the price or more. Of the people who
preferred the ‘combination chicken’, approximately 40%
indicated to be willing to pay the concomitant extra
price.
In the focus groups the costs and price were frequently
discussed. A number of people indicated to be willing to
pay more.
Conclusions and recommendations
Discussion within the context of the current livestock
sector practice or beyond?
Alternatives to the killing of one-day-old chicks can be
discussed within the framework of the current poultry
sector. Than, it is investigated whether one aspect
of current practice, killing one-day-old chicks, can be
improved. The issue of killing one-day-old chicks can
also be broadened: killing the males is a symptom of the
practices in the intensive livestock sector, which in its
entirety can also be brought up for discussion.
Whether the participants in the public inquiry started from
the limited context, or brought up the intensive livestock
industry in its entirety for discussion, we do not know. The
focus group participants often made comments such as
‘the chickens do not have a good life’, ‘it can be questioned
what is better for such a male’, ‘the combination chicken
is a chicken as it should be’. It can be understood that
the participants also considered the broad context and
had questions as to the intensive livestock industry in its
entirety.
In the evaluation of the results of the research with
stakeholders and ethicists it became clear that the choice
of the context is also determinant for the preferences
of solutions, particularly for the preference for the
combination chicken. If the current practice is assumed,
the practice of killing males can be changed in a relatively
short term with the development of a technological
alternative. However, in the long term a new discussion
can be brought up about other characteristics of intensive
livestock farming, where the combination chicken can
possibly be a more structural solution to the lack of animal
welfare experienced for today’s poultry, but would be a
step backwards in sustainability as far as feed and energy
are concerned. The research into alternatives has been set
up from the current context and thus within the framework
of current practice: are there any alternatives to the
killing of males in the intensive poultry sector. The results,
therefore, should also be considered within this context.
The (un)desirability of the intensive livestock industry in
its an entirety cannot only be discussed via the case of
the one-day-old males, but the latter can certainly be used
in this discussion. Given the signals from the society, a
discussion about intensive livestock farming in its entirety
is certainly in order.
The research has shown that people need more
information to be able to form an adequate opinion
about the subject, but that they are very well able to
think about the issue with the available information.
In forming their opinions they seem to make complex
considerations. According to the participants, the
information by means of a documentary has supported
the research strongly. With this visual support such a
complex issue can be made discussible more easily. The
subject at large and the alternatives to killing the males
are complex and there is little information available on
the different alternatives as to feasibility, costs and
effects on the animal. This means that our research is
a first contribution to forming an opinion and that the
results are provisional. If more information becomes
available on feasibility and effects of alternatives,
the definite judgement can change, which cannot be
predicted yet. The study shows, however, that many
people are ignorant of the fact how male chicks are killed, but that, if they know, they feel uncomfortable about
it. It is, therefore, useful to conduct further research into the feasibility of technological alternatives and to
accompany that with a further evaluation and monitoring of the societal acceptance of such alternatives.
Neither the public inquiry, nor the focus groups produced a clear preference for one of the alternatives. Some
options can, however, be considered unacceptable. In general, killing of embryos is considered undesirable
and destroying a late embryo is not regarded as an adequate alternative to killing the chick. Applying genetic
modification is extremely controversial, although acceptance depends on the specific approach. If genetic
modification makes it possible to be able to see the difference between males and females in a freshly laid egg,
this seems an acceptable alternative. But if genetic modification makes it possible that male embryos develop to
female chicks or that males die as embryos, this is broadly repudiated. Accepting the current situation, killing the
males, scores relatively high, but yet people adhere to looking for alternatives. A limited number of alternatives
qualify for further research. This research should relate to the feasibility and be accompanied by further research
into societal acceptance.
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6. The best or rather ‘least bad’ options are in order:
Looking into the freshly laid egg and not hatching the male eggs
The option ‘looking into the fresh egg and not hatching the male eggs’ has the highest score of the alternatives
that can be carried out within the current poultry sector. Research into the technical feasibility of this option is
recommended. It is estimated that a brief study is sufficient to examine whether this alternative is possible or not
as to biological principles.
The combination chicken
The combination chicken can be attractive for a niche market, but will not be a solution for the entire poultry
sector, for example, due to the structurally less efficient use of feed and energy.
Influencing the sex ratio by adapting the environmental factors of the hen, so that fewer (no) male chicks are
born
The option ‘influencing the sex ratio by adapting the environmental factors of the hen’ does not score higher
than maintaining the current practice of killing the chicks, but yet rather positive. Therefore and on the basis
of further analysis by the project group (see box ‘Some alternatives reconsidered’), ‘influencing the chicken by
environmental factors’ can be regarded as a possible alternative. Particularly, because recently researchers have
indicated that the feasibility of this alternative is relatively high.
Bringing a photogenic protein into the embryo by genetic modification, so that the difference between male and
female embryos can be detected in a better way
Although genetic modification as such is controversial, this alternative may lead to the possibility of detecting the
difference between male and female embryos in the freshly laid eggs.
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7. We (as the project group) have reconsidered some alternatives, where important values mentioned in the focus
groups and the public inquiry have been used.
‘Looking into the freshly laid egg and not hatching the males’
Animal friendliness: positive, for the males are not born and thus not destroyed. Precondition is that the sampling of the eggs
does not carry a risk as to health and welfare of the female embryos that are hatched.
Naturalness: neutral, taking a sample from an egg and examine it is neither positive nor negative as to naturalness.
Feasibility: scientific literature provides positive indications, but no hard proof that this would be possible; the experts indicate
that in approximately 6 months it can be figured out whether the composition of a yolk from which a female chick grows differs
from that from which a male grows.
Costs: if the principle is feasible, robots and thus expensive equipment are necessary. However, costs of hatching capacity and
labour decrease. Neutral?
‘Combination chicken’
Animal friendliness: positive, for the roosters of such a breed have fewer leg and heart problems than today’s broilers and as
a parent animal such breed need not be put on rations, which is current practice in broiler parent stock. If the farming conditions
of laying hens do not change and are qualified as disagreeable, more hens are to be subjected to those circumstances, however,
for a same egg production.
Naturalness: positive, for also the roosters have a time to live. A combination chicken also looks ‘natural’.
Feasibility: realistic for a niche market, not as a substitute for the entire poultry production.
Costs: considerably higher, because the hens need more feed and room per egg than the current laying hens and the roosters
as broilers need more feed and time per kg/chicken than the current broilers. At similar egg and meat production, the need for
raw material is doubled and also more manure, dust and ammonia are produced per unit of product.
‘Influencing the sex ratio by adapting the environmental factors of the chicken’
Animal friendliness: depends on the influencing factors. If a light scheme is used or a particular feed composition, the animal
friendliness is not at issue, but if hormone injections are needed, it does. For the chicks neutral to positive.
Naturalness: depends on the influencing factors. The principle as such is natural.
Feasibility: the principle has been proved, but whether a full 100% of females can be reached remains the question
Costs: in principle fewer costs than in the current practice. If almost no males are born, this will lead to considerable savings in
the hatching industry.
‘Genetic modification’
Animal friendliness: negative due to laboratory animals that are needed to develop the method; positive in realisation.
Naturalness: genetic modification is regarded as ‘unnatural’, though not by all people.
Feasibility: not much can be said about the technical feasibility at this stage; at the moment research on genetic modification for
this goal is prohibited in the Netherlands.
Costs: if a stable insertion can be reached, costs are low.
‘Looking into the egg, early or late embryo’
Animal friendliness: the earlier the detection of the sex and thus killing the male embryos, the more animal friendly the method
is. Focus groups and public inquiry indicate that killing embryos is not a pleasant thought.
Naturalness: neutral, but less than ‘fresh egg’.
Feasibility: from day 13 of the hatching process it has been proved that a reliable distinction can be made between male and
female embryos. The technique of sexing late embryos from approximately day 16 is available in principle (and patented), but not
used in practice. From approximately 4 days of incubation, a difference in gene expression between male and female embryos
starts, after which time in principle (blood) cells can be sampled and a distinction could be made.
Costs: comparable to ‘fresh egg’; decrease in costs in the hatchery is less, however.
‘Crossing the chicken, so that male embryos die’
Animal friendliness: comparable to killing the embryos after sexing. Also dependent on possible side effects of the lethal genes
in hens.
Naturalness: in principle, it is an entirely natural process; focus groups and the public inquiry consider this as manipulation and
unnatural, however.
Feasibility: with the current knowledge of the genomics of the chicken, looking for likely genes is well possible. To what extent
this can be successful in a crossing programme should be investigated further.
Costs: if there are no or almost no side effects in the hens (precondition), the costs are minor.
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