Science - March 24, 2011

The future of the day-old chick

Millions of day-old chicks are killed every year in the poultry sector because they will make neither layers nor eaters. Protest against this practice is getting louder and louder. But what are the alternatives? Livestock research lined them up and explained them in lay terms to a selection of Dutch citizens.

Four days after incubation a chicken embryo has distinguishable blood vessels, brains and a beating heart.
Forty million day-old chicks are slaughtered every year in the Netherlands. That means 100,000 per day, and about 1,000 in the time it takes you to read this article.
The doomed birds are the males among the layers, because they don't lay eggs but are not suitable for meat production either, as the highly specialized poultry sector uses different breeds for egg and for meat production. From an economic point of view, the males of the layer breeds are useless so once they have hatched out they are killed. Opponents of intensive animal farming see this practice as a perfect example of the extremes of industrial food production that shows no respect for animal lives. They reject this 'systematic mass killing' of day-old chicks on ethical grounds. The Dutch animal rights party campaigns against the slaughter but it is not the only party that would welcome a change of practice. A resolution to look for alternatives was passed in the Dutch parliament several years ago. So are there real alternatives?

A line-up of the options
Henri Woelder and Ferry Leenstra of Livestock Research lined up the available alternatives and, together with the Rathenau Institute and the agricultural economics institute LEI, put them to several focus groups and 2,000 Dutch citizens through an internet survey. Participants in the survey were first shown a film on current practice and an explanation of the possible alternatives. Woelders and Leenstra published the results last month in the journal Animal Welfare.So what were the options and what did people think of them?
Option 1: 'The dual purpose chick'
These are the sorts of chickens that people keep in their back yards, says Leenstra. They lay eggs and then end up in the soup. The point is: chickens cannot both lay large numbers of eggs and grow fast for meat production. A laying hen needs strong muscles and therefore needs more feed and space. Then there is the fact that the males of the layer breeds do not grow so fast and therefore require more time, feed and space before they are the right weight for slaughtering. With a dual purpose chicken you always have to compromise on something. The cost price and the ecological footprint are optimal with current practice, says Leenstra. And yet the people responding to the survey thought the dual purpose chicken was a great idea. The point is though, that both the eggs and the meat from this kind of chicken are twice as expensive as those of the specialized chicken. And that puts people off.
Option 2: Only hatch out the hens
This is no simple matter. It is technically possible to take a sample from the egg, but to date no indicator has been found for telling males and females apart in a freshly laid egg. So that won't work. You can also make male embryos die off spontaneously in the egg. For that, you need to identify hereditary genetic deviations among the males at the embryo stage, and use them in the breeding programme. But respondents did not think that was a good idea. So that is off the cards, as is the idea of ensuring that males turn into females in the embryo. This would be possible if Livestock Research can find genetic mutations in which sexual development deviates from the norm. The internet panel rejected this approach too. The only remaining options is to make use of natural mechanisms that birds appear to have at their disposal for making a hen produce more female eggs and fewer male ones. Livestock Research is already doing research on this.
Option 3: Genetic modification
This option would involve using genetic modification to determine the sex of the freshly laid egg. You do that by, for instance, introducing a gene for a fluorescent protein into the chicken genome. Light-emitting sea creatures could provide such a gene. It seems theoretically feasible to get only males or only females to light up in the egg, so that you can select them. 'First we shall find out whether we can measure the light signal properly. At the same time, we look into the possibilities for introducing the gene into the chicken genome in the right way. If you manage all that, you can hatch out only the female eggs.'
Option 4: Selection of embryos
A chicken egg hatches out in the space of three weeks. After two weeks, you can determine the sex of the egg through hormone levels. The method for doing this has already been patented. The remaining question is whether this screening can be automatized so that you can quickly sort thousands of eggs into males and females. Then you kill only the male embryos. The people assessing the alternatives did not see this as an improvement on killing the day-old chicks. In fact they preferred the current practice to the option of destroying the embryos.
Option 5: Continuing current practice
Current practice involves stunning and freezing 40 million male day-old chicks. They are not thrown away but are sent to zoos as feed for carnivores and carrion eaters. This is why there is a preference for this option above option 4, killing off the embryos. But there are still ethical objections to the current practice.
So what is best?
The survey shows that there is no ideal solution, says Leenstra. Every solution comes with its own limitations and down sides. The combination chicken could be an interesting niche product for fans of organic produce, for example, who are willing to pay a bit more for such products. There are also some poultry farmers who want to produce them but they need to have a market for them. 'My conclusion is: it is a partial solution but is certainly not an alternative suited to the entire poultry sector.'
The gene technology chicken is supported by some people, says Leenstra. But another group is dead set against this technology as they oppose genetic modification on principle. Anyway, this is not an alternative for the time being, in view of the demands of developing it, establishing its legal basis, getting it accepted by consumers and carrying out the many tests required to establish its safety for humans and animals. Nor is the option of using natural mechanisms to make laying hens produce more female than male eggs realistic for the time being. All in all, Leenstra thinks that the current practice cannot be banned in the immediate future. In due course he envisages a choice coming up between the expensive combi chicken (option 1) and the gene technology chicken (option 3).

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