Do stress levels represent the effort spent to access food? A comparative study between mules and equines

• Grant number: 15/19626-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: December 01, 2015
• End date: November 30, 2016
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Ecology of Domestic Animals and Ethology
• Principal Investigator: José Nicolau Prospero Puoli Filho
• Grantee: Marcela Fernanda Delagracia
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil

Abstract

Motivation tests have been used to determine the importance of resources or environmental conditions for animals to improve their health conditions. In such tests, motivation is often inferred from behaviors indicative of physical effort that animals apply to access such resources. Generally, food is an item used as a reference resource for evaluating the effort for the other available items. Stress responses may be associated with intensity of effort to access an important resource, since conditions that difficult the access for such resources generate a stressful situation. However, this approach has been basically neglected in the literature. Taking into account that horses and mules are considered as important animals for the national economy, we will evaluate whether stress responses indicate the effort spent by horses and mules to access the concentrated food. For this, we will test if the stress levels of horses and mules (n = 8 of each species) increase proportionally with the increase of the physical effort (motivation) required to access the food. The access to the concentrated food will be blocked by a fence, whose weight will be gradually increased over a three-day test, thus representing a gradual increase in the effort required to cross the fence and reach the food item. On each test day, we will measure the plasma cortisol levels (stress indicator) of each individual before and after the effort to access the food. The daily order in which the individuals will be tested will be randomized by raffling. In order to accurately determine the weights to be added to the fence, pilot tests will be carried out with the animals in the same study conditions. (AU)