Cortisol as an Indicator of Stress in Animals Under Different Grazing Systems

Project Overview

Project Type: Graduate Student
Funds awarded in 2019: $13,500.00
Projected End Date: 08/31/2021
Grant Recipient: Virginia Tech
Region: Southern
State: Virginia
Graduate Student:
Major Professor:
John Fike
school of Plant and Environmental Sciences, Va Tech


  • Animals: sheep


  • Animal Production: animal protection and health
  • Crop Production: silvopasture

    Proposal abstract:

    Animal welfare is a top priority among livestock producers. In the Southeast, heat stress is one of the main concerns that decreases productivity and has significant economic consequences. However, heat stress could be minimized by integrating animals into the tree production system such as silvopastures, that can ultimately improve their performance. As the level of cortisol in animals increases in response to heat stress, it can be a good indicator of stress management in animals. Limited studies have been carried out to compare the cortisol level of animals in hardwood silvopastures versus open pasture systems. This study aims to compare the hair and fecal cortisol level of sheep as an indicator of stress in hardwood silvopastures versus open pastures. The study will be carried out at the Whitethorne Agroforestry Demonstration Center at Virginia Tech's Kentland Farm in Blacksburg, VA. The study will consist of three experimental treatments -- black walnut (Juglans nigra) and honey locust (Gleditsia triacanthos) based silvopasture, and open pasture treatments in a randomized complete block design. Pastures will be rotationally stocked with sheep based upon forage availability. On day 1 and 21, hair samples will be clipped using an electric razor and will be analyzed for cortisol level. Similarly, fecal samples will be collected from animals and will be analyzed for fecal cortisol metabolites. As heat stress of animals in silvopastures is minimized due to shading, it is expected that the cortisol level of animals in silvopasture would be significantly less than those in open pasture.

    Project objectives from proposal:

    To compare the stress levels of sheep in black walnut (Juglans nigra) and honeylocust (Gleditsia triacanthos)-based silvopastures with that of sheep in open pasture using non-invasive measures, specifically hair and fecal glucocortisol.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.