Dual-purpose strains, with hens housed for egg laying and roosters kept for meat production are one alternative to the killing of male day-old chickens. However, dual-purpose hens seem to have additional advantages compared to conventional layers, for instance, a lower tendency to develop behavioral disorders, such as feather pecking and cannibalism. In the present study, three batches of about 1850 conventional layers (Lohmann Brown plus, LB+) and 1850 dual-purpose hens (Lohmann Dual, LD) each, all of them with untrimmed beaks, were observed during production (20-71 (56) weeks of life) in a semi-commercial aviary system. The aim was to investigate whether the hybrid and batch affected the occurrence of injurious pecking, and to identify a detailed time course of the damage caused by this behavior. Therefore, the hens' plumage and skin condition were assessed as an indicator by means of a visual scoring method. The LB+ hens had higher production performances and higher mortality rates compared to the LD hens. Plumage loss in the LB+ flocks started at 23 to 25 weeks of age, and deteriorated continuously. The LD hens showed only moderate feather loss on the head/neck region, which started at 34 to 41 weeks and remained almost constant until the end of the observations. Compared to feather loss, injuries occurred in the LB+ hens with a delay of several weeks, with a maximum of 8% to 12% of hens affected. In contrast, skin injuries were observed only sporadically in single LD hens. In all batches, hybrid had an effect on the occurrence of feather loss (p < 0.05). Within the LB+ strain, the proportions of hens affected by plumage loss and injuries differed among batches (p < 0.05), whereas this was not the case in the LD flocks. Thus, severe feather pecking and cannibalism seemed to occur in the conventional layer hybrids but not in the dual-purpose hens, though both genetic strains were raised and managed under the same semi-commercial conditions. Therefore, keeping dual-purpose hens should also be considered as an alternative approach to avoid injurious pecking in laying hen husbandry.
Keywords: animal welfare; cannibalism; feather pecking; injury; integument damage; laying hens; plumage loss.