Emotions are crucial for animal welfare, yet our understanding of emotions in farm animals is still sparse. To characterise the range of their emotions, we followed a strategy derived from cognitive psychology, in which emotions experienced by an individual result from its evaluation of the situation according to a set of criteria (novelty, suddenness, pleasantness, expectancy and controllability). We placed three-month-old lambs in experimental situations where the evaluation was oriented to only one criterion, and used a psychophysiological approach to identify the behavioral and physiological responses specific to that criterion.

Using video cameras positioned at various angles, we recorded fine movements (such as head posture and ear movements) made by the lambs in response to the suddenness or novelty of a visual stimulus. The behavioral response of the lamb was recorded by focal sampling on a computer using the event recorder software, The Observer Video-Pro. To record the startle response, an accelerometer was fixed on the back of the lamb. We also recorded cardiac and respiratory activities, along with skin temperature. Since these measures had to be made in a short time interval on freely behaving lambs, without any interference or manipulation, the animals were equipped with a non-invasive instrumentation pack.

For cardiac monitoring, two Ag/AgCl adhesives and pre-gelled electrodes were used. A pneumograph (PneumoTrace, model 1132, UFI) placed around the abdomen was used to record respiratory activity. Finally, the temperature was recorded with two thermal sensors: one on the head (attached with an elasticised strap) and one on the thigh (attached by a velcro patch, with one side glued onto the animal). These four types of psychophysiological signals were transmitted via radio telemetry: the four transmitters were fitted on an elasticised girth strap (model Lombogib Gibortho, Gibaud S.A., France), which also secured the cardiac electrodes. In total, the pack weighed 1.04 kg (4% of the weight of a three-month-old lamb).

The cardiac and respiratory transmitters used for the startle response were part of monitoring units with analog transmission (Life Scope 6 model OEC-6301K, Nihon Kodhen, Japan). The temperature transmitter was part of a multi-channel monitoring unit with an analog-digital converter (model Modem Radio R4MT, HTS Electronique & CEM, France). All of the monitoring unit receptors were connected to an Apple Power PC equipped with Chart Software (version 3.6.8) via a PowerLab (both ADInstruments, Australia).

Our initial results show that it is possible to record all these parameters concurrently. Most of the parameters vary when the animals are placed in a stressful situation, but the pattern of responses varies according to the situation.

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