1. A total of 257 farmers with free ranging laying hens (organic and conventional) in Switzerland, France and The Netherlands with 273 flocks were interviewed to determine the relationships between the genotype of the hens, management conditions and performance. 2. Almost 20 different genotypes (brands) were present on the farms. In France, all birds were brown feathered hens laying brown eggs. In Switzerland and The Netherlands, there were brown, white (white feathered hens laying white eggs) and silver (white feathered hens laying brown eggs) hens. In Switzerland, mixed flocks were also present. 3. The overall effect of system (organic vs. conventional free range) on egg production and mortality was significant, with higher mortality and lower egg production among organic hens. In pair wise comparisons within country, the difference was highly significant in The Netherlands, and showed a non-significant tendency in the same direction in Switzerland and France. 4. White hens tended to perform better than brown hens. Silver hens appeared to have a higher mortality and lower production per hen housed at 60 weeks of age. 5. There were no significant relationships between production, mortality, feather condition and use of outside run or with flock size. 6. There was more variation in mortality and egg production among farms with a small flock size than among farms with a large flock size.
Leenstra, F. R., Maurer, V., Bestman, M. W. P., Sambeek van, F., Zeltner, E., Reuvekamp, B. F. J., ... van Niekerk, T. G. C. M. (2012). Performance of commercial laying hen genotypes on free range and organic farms in Switzerland, France and The Netherlands. British Poultry Science, 53(3), 282-290. https://doi.org/10.1080/00071668.2012.703774