According to the results of a project headed by Piter Bijma with the Breeding and Genetics Group from Wageningen University in the Netherlands, selective breeding of chickens with an eye towards social conduct may reduce flock mortality by as much as two-thirds, resulting in rates comparable to those when using the beak-trimming method.
Together with researcher Esther Ellen, Bijma studied 1,000 beak-trimmed layers in cages. Total mortality among the chickens was 30% due to aggressive picking, but the per-cage mortality numbers differed. The two researchers took the chickens from the cages with the lowest mortality rates and bred them. After the third selection round, each time taking the most "social" chickens and breeding them, mortality rates had dropped to roughly 12%. "These figures come close to the figures of beak-trimmed layers, where the normal mortality rate is around 10%," said Bijma.
The next research step, according to Bijma and Ellen, is to breed another two generations of layers to see if the mortality rate will continue to fall and possibly reach the 10% number.