Wetenschap - 28 februari 2011

Selection eliminates antisocial animals

A Wageningen researcher is breeding peaceful chickens. This almost halves deaths in chicken runs.

As every chicken farmer knows, if you put chickens together in a cage they will start pecking each other to death. To prevent this, their beaks are trimmed. But there is growing resistance to this practice among the general public. Piter Bijma of the Animal Breeding and Genetics group is therefore working on an alternative solution. Four years ago, he and postdoc Esther Ellen started an experiment with a thousand laying hens with untrimmed beaks in battery cages. When these white Leghorn chickens were kept in battery cages for eighteen months - their working lives - around thirty percent of them were pecked to death. But the number of deaths varied per cage.
Bijma and Ellen selected the chickens from the cages with the lowest number of deaths and bred from them. The death rate among the second generation of sociable chickens was 22 percent and in the subsequent selection rounds the rate went down to 18 and 12 percent. That is more like it, says Bijma, because in cages with laying chickens that do have trimmed beaks the death rate may also be as much as 10 percent. Bijma and Ellen want to get below 10 percent with their breeding programme. They aim to breed two more generations of sociable chickens to see whether they can maintain the low death rates in this group.
Beak trimming banned
The breeding company Hendrix Genetics, the partner with which Bijma is carrying out the research, is enthusiastic about the breeding programme. Beak trimming is already banned in organic farming in the Netherlands. The conventional poultry farming sector has also drawn up an action plan to outlaw the practice. On top of that, use of the classic battery cages will be banned from 2012 onwards. Laying hens are increasingly kept in aviary systems where they can move about freely, but there too hens peck each other to death.
It is more difficult to identify the chickens doing the pecking and remove them in a stall like that.
The successful results with chickens have led to similar research being started on peaceful pigs. Bijma is involved in the study by Liesbeth Bolhuis aimed at selecting pigs for their social skills. Sociable pigs do more 'nosing' - cuddling pig-style. That improves the atmosphere in the barn and makes their fellow pigs grow more. It seems sociable behaviour may be correlated with better growth, says Bijma. Breeding company Topigs is considering using the Bijma method in its breeding programme.