Two groups of 38 hens, commercial medium and light hybrid strains, were housed in outside pens, 23 x 21 m, and compared over a 20-month laying period with controls in groups of 4 in battery cages. They received the same laying mash in a feeding trough kept inside their hut, and almost all eggs were laid in nest boxes also inside the hut. Supplementary light was provided when necessary before the natural dawn by a bulb inside the hut, so that the photoperiod was at least 14 h. The birds outside produced on average as many eggs as those inside and of a greater mean weight. They ate more food and in addition supplemented their diet with a variable amount of grass. Mortality was similar in the 2 systems, while feather condition was better in birds in pens and their body weight was greater. Access to the outside pens was provided between 0800-1700 h, and the number outside was dependent on weather conditions, the proportions were lower for the light hybrids. The numbers were not static, there being a relatively constant high rate of movement into and out of the hut. The number emerging within 5 min after the pop-hole was opened at 0800 h was very variable from day to day, but showed a very high correlation between the 2 flocks. The main activities observed outside were grazing, ground pecking, ground scratching and dust-bathing when weather conditions were appropriate. There was no evidence from production results or mortality data, that modern hybrids are specifically adapted to either intensive or extensive systems.
|Publication Title||Applied Animal Ethology|
|Author Address||ARC Poultry Res. Cent., Roslin, Midlothian, UK.|
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