The effect of feather eating on feed passage in laying hens.

Previous work has demonstrated an association between feather pecking and feather eating in laying hens. This raised the question of the dietary effect of feathers. We hypothesized that feathers, as indigestible components, have similar effects as insoluble fiber, i.e., speeding up feed passage. Twenty-four adult laying hens each of a high (H) and a low (L) feather pecking line were kept in individual cages and fed a commercial pelleted diet ad libitum. One-half of each line was offered downy feathers (HF; LF) of the same genetic line. The other half of the birds were kept as control without access to feathers (H0; L0). After a 6-wk feeding period, 5 birds of each group were selected for determination of feed passage. The HF birds with the highest number of feathers eaten and the LF birds with the lowest number of feathers eaten were used. Selection of L0 and H0 birds was carried out at random. Feed passage was determined over 48 h using titanium dioxide as a marker. The number of feathers eaten was significantly higher in HF birds than in LF birds before (P < 0.001) and during 48 h of marker excretion (P < 0.02). The time when 50% of the plateau level of excretion of the TiO2 was reached differed significantly among all groups; the shortest time was observed for the HF group (P < 0.05). The results clearly show that feathers increase the speed of feed passage and, in this regard, show similar effects as insoluble fiber. The dietary effect of feathers may be a crucial factor in the development of feather pecking and the related damages to the feather cover in laying hens.