Strength of preference for dustbathing and foraging substrates in laying hens

The present experiment investigated the substrate preferences of laying hens, with particular respect to dustbathing and foraging behaviour, in order to guide decisions concerning which resources should be provided in laying hen housing systems to best enable the expression of these behaviours. The consumer demand approach was used to study the strength of preference. Individually-tested hens had to push a weighted door to enter one of four resource areas containing either a wire floor, or sand, wood shavings or peat moss as substrate. The contents of the resource areas were clearly visible from the central home pen. Twelve ISA-Brown hens, reared in battery cages, successfully learned to operate the push door. Most of these hens worked to get access to all the resource areas. With respect to all visits to the resource areas, the slopes of the demand curves for the numbers of entries to the resource areas were steep and not significantly different. Furthermore, no differences were found in the maximum price paid for access to the various substrates or in the total expenditures. These findings indicate that the hens showed no preference for wire or any other substrate per se. However, when the hens showed dustbathing, almost all of them had worked for access to peat moss whereas only some had worked for sand or wood shavings. The slope of the demand curve for dustbathing in peat moss was relatively shallow and the maximum price paid and the total expenditure to take a dustbath in peat moss were significantly higher than those found for sand or wood shavings. With respect to foraging behaviour we found no clear substrate preference. We conclude that the value of a particular substrate varies according to its suitability for the expression of specific behaviours, and that there is a strong demand for peat moss for dustbathing.