Degree of synchronous feeding behavior of two types of laying hybrid hens in battery cages with a feeder space of 12 cm per hen

There is a considerable lack of scientific evidence on the necessary feeder space with respect to the legal requirement that all hens of one battery cage must be able to feed simultaneously. Moreover it is likely that hens from different lines, differing in weight and width, have different space needs at the feeding trough. In order to ascertain the degree of simultaneous feeding in two types of laying hybrids with different weights, feeding activity was recorded in 29 cages, populated with four hens each with a feeder space of 12 cm per hen. Recordings took place over 6 days at seven feeding times under ad libitum feeding conditions. In all cages, the lighter and apparently slimmer LSL-hens (Lohmann Selected Leghorn, white) were able to feed simultaneously. However, for the somewhat heavier and apparently broader LT-hens (Lohmann Tradition, brown) this could not be observed in two of 16 cages. Nevertheless, was the average proportion of cages higher in LT-hens in which synchronous feeding of all hens could be noted at least once within each 30 minutes observation period. These were 35% of cages (LT) compared to 18% in LSL-hens (p < 0.001). Therefore, not only the physical space needs, but also possible differences in social and feeding behaviour may affect synchrony in different lines. In general, the proportion of observation time with simultaneous feeding was low (3.3% in LT, 1.7% in LSL, n.s.). As there are no comparable figures available for different feeder space allowances from the literature, an assessment of the presented data is not possible. Investigations on the synchrony of feeding behaviour in small groups of laying hens under varying environmental conditions and in different layer lines should be continued.