The Swiss Animal Welfare Act decrees that the housing conditions of farm animals must guarantee animal welfare. In the process of developing a method to test nest boxes for their suitability for laying hens, we conducted an investigation using preference testing. It was aimed at verifying the occurrence of different types of layers within the same laying strain and to investigate the choice of a nest site. At the onset of lay, 24 individually housed hens were given the choice of 2 nest sites: a nest box or a litter tray. The chosen nest site and the behavior of the hen, 1 h prior to oviposition, were recorded at 3 stages during the period in which the first 20 eggs were laid. The majority (17) of the hens laid consistently in the nest box, and 7 hens laid consistently in the litter tray. Litter layers spent more time exploring during the hour prior to oviposition than did nest layers, and their final nest visit (when an egg was laid) was shorter. There was no significant difference in the number of entries into the chosen nest site between layers of the 2 types. As expected, the level of restlessness of hens decreased with laying experience. In the hour prior to oviposition, the frequency of foraging and resting increased, whereas the frequency of exploring and nest seeking decreased, and the number of nest-site visits declined. We conclude that there may be at least 2 different types of laying hens that show different nest-site preferences, with concomitantly different prelaying behavior.
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