Elasticity of demand for food and sand in laying hens subjected to variable wind speed

Abstract

A problem associated with the application of consumer demand theory to operant conditioning experiments is that the task set may be impossible to perform. One solution to this problem is to use an unpleasant stimulus of varying magnitude as the cost rather than work (operant task). In this experiment wind was used as the cost to confirm that consumer demand theory was applicable to food consumption when laying hens were exposed to varying wind speeds. Hens were deprived of food for 0, 12 or 24 h and allowed to feed at feeders exposed to wind speeds from 0 to 6 m s −1. The aim of this experiment was to test the hypothesis that the longer the period of food deprivation, the more inelastic the demand for food would become. A similar protocol was used to test the elasticity of the demand for sand as opposed to the demand for wire mesh. The experimental results indicated that exposure to wind was aversive to hens and that after 24 h of food deprivation, the demand for food was more inelastic (slope of feeding time against wind speed was 3.11) than after 12 h (3.95) or 0 h (4.40) (one tailed P < 0.05). Demand for access to sand was similar to that for wire mesh. These results confirm that wind can be used to impose a cost on a resource and that access to sand is not a need for laying hens despite the fact that sand is preferred to wire mesh floors.