Oiling behaviour and the effect of lipids on dustbathing behaviour in laying hens Gallus gallus domesticus.

Laying hens oiled the plumage twice a day, while oiling behaviour consisted of a bout of five oilings (median value). During one oiling, a hen collected lipids from the preen gland with her bill and subsequently performed (as a median) five strokes or rubs over and through the feathers. The breast was oiled most, whereas during later oilings within an oiling bout the wings and the flanks were oiled as well. The back and the tail were seldom oiled. An artificial distribution of stale uropygial gland lipids in a more or less natural way on the breast feathers within a 3-day period of sand deprivation resulted in an increase of the duration of the first dustbath after the deprivation by 12%, compared with a control treatment. Within the dustbath, the total number of the side-lying and side-rubbing elements - two related consummatory dustbathing elements - doubled and tripled, respectively. In contrast to these highly significant effects, the duration of the dustbathing did not change after a fresh uropygial gland lipid treatment, while the effects on side-rubbing and side-lying were not straightforward; the total number of the side-rubbing element was doubled, but the duration of side-lying was reduced by 29%. The results are discussed in relation to the chosen methodology and the maintenance of the lipid condition of the integument.