Welfare by the ear: Measuring ear positions of sheep with an ART tracking system

Swiss institutes examine the correlation between sheep’s ear postures and their emotional states


General information

In 2012 and 2013, the Centre for Proper Housing of Ruminants and Pigs, Federal Food Safety and Veterinary Office FSVO and Agroscope, Institute for Livestock Science in Tänikon, Switzerland*, conducted their studies in observing and measuring ear positions of sheep while stimulating them in three different levels: with the help of an automated mechanical device fixed at the upper breast of the sheep by a belt system. The stimuli ranged from pricking (without injury) with metal pins against the sheep’s body, over just pressing against the body with a metal plate to (as the presumed positive stimulation) “massaging” the sheep with the plate.
The automated measurements supported by the infrared tracking system can be a very useful instrument for studies relying on the evaluation of ear postures and movements for the understanding of emotional reactions in sheep and other similarly sized animals.
* Academic responsibles and authors of the scientific thesis: S. Vögeli, B. Wechsler and L. Gygax

ART tracking solution

Ear postures and movements were recorded by ART’s TRACKPACK4 system using reflective marker balls tracked by four infra-red cameras in 3D. The cameras were placed in the four top corners of the test pen and connected with a TRACKPACK controller calculating the positions of the marker balls. These positions were then transmitted to a remote PC. A single marker was placed on the back side of each ear (‘ear target’). In addition, a 6D head target with four markers was used.

Why ART?

Three main reasons convinced the researcher team for chosing ART:

  • The simple and quick set up of the TRACKPACK system
  • The good support of the ART team during the installation
  • The accurate and stable automated tracking process minimized the duration of the whole measurement process in favour of the sheep’s welfare (which was a very important requirement for the researchers)


  • TRACKPACK4 system
  • TRACKPACK controller
  • 2 “ear targets” (single markers)
  • 1 6D head target
  • 1 sheep pen representing the tracking cave