Dustbathing as related to proximal and distal feather lipids in laying hens

After a prolonged experience with wood-shavings or with sand, 2 x 11 hens (Gallus gallus domesticus) were litter-deprived. Prior to the 7 to 8 day deprivation period feather samples were taken. This was repeated immediately after the deprivation had ended and right after the first bath in the familiar litter. Each feather was cut at the transition between the proximal plumulous and distal pennaceous part and lipids were extracted from separate samples, containing one type of feather parts. Hens on wood-shavings bathed 10 minutes longer after deprivation than hens on sand. This was due only to an extension of the second phase of the dustbath, which included rubbing; the first phase of tossing did not differ. In the extended phase of the wood-shavings bath the tendency to rub was lower, whereas the tendency to toss was higher than in the comparable phase of the sand bath. Thus, litter quality affected the amount of rubbings and of tossings in between. Rubbing did not effectuate a close contact between wood-shavings and the proximal integument, as wood-shavings could not be tossed into the plumage. This contrasted with baths in sand and only these baths resulted in a removal of excessive lipids from the plumulous parts. Therefore rubbing seems functionally crucial. The lipid level immediately after deprivation and the change in the quantity of lipids due to deprivation positively correlated with the amount of tossings in wood-shavings and with the amount of rubbings in sand. This indicates that the lipid condition is causally involved in dustbathing.