Hens that live and let live

Tuesday, August 4, 2009

The Agricultural Research Service, part of the United States Department of Agriculture (USDA), has developed a line of less aggressive hens that still produce a lot of eggs. The goal is to cut mortality in group-housed flocks without the usual, less than welfare-friendly beak trimming.

Housed together to an age of 54 weeks in communal cages rather than battery cages, commercial birds are merciless and suffer an 89 per cent mortality rate compared to 20 per cent for the less aggressive, newly developed line of birds. The gentler birds also produced more eggs.

A press release from the USDA says that, over 20 years of breeding selection, egg production has increased significantly in one particular breeding line of laying hens while mortality due to aggression and cannibalism among birds with untrimmed beaks increased tenfold.

Biologist Heng-wei Cheng speculates that the less aggressive behaviour may be due to a decrease in dopamine levels in the birds. Dopamine, secreted by the brain, is associated with dysfunctional behaviour and a decreased ability to deal with stress.