Production and economic results of commercial flocks with white layers in aviary systems and battery cages.

1. In the Netherlands aviary systems are in use on 19 commercial farms. In the present study the results of 19 flocks kept in aviaries, with an average flocksize of 16,000 hens, were analysed and compared with 47 flocks kept in battery cages. 2. The aviary flocks had lower egg weights, lower mortality rates and poorer food conversion. The difference in food intake per hen per day was not significant. The average percentage of floor eggs in aviaries was 4.6, ranging from 0.9 to 11.5. 3. Production costs per kg eggs produced in aviaries were 8.2% greater than in cages. This increase was mainly caused by higher costs for pullets, housing and labour.