Energy balance and feeding motivation of sheep in a demand test

The measurement of strength of motivation has become an important tool used to assess the resources that an animal values and, subsequently, to aid in determining its welfare. However, the relationship between animal motivation and welfare state is not well defined with conclusions based on the assumption that welfare is reduced if a 'valued' resource is not provided. One way to better identify the relationship between the level of motivation and welfare state is by investigating the mechanisms that affect motivation in a demand test. This study therefore aimed to test the hypothesis that energy balance (energy expended = energy consumed) could determine the motivation to work for food and ascertain if this balance could be altered by gut storage levels. A secondary aim was to test the hypothesis that two measures of demand (Pmax or point of maximum work, and maximum price paid (MPP) or point of work ceasing) would be equally responsive to changes in energy balance.