Investigating cow body language is a first step toward a reliable method to assess emotional states in cattle, according to researchers from the Swedish University of Agricultural Sciences (SLU).

In an article published in PLOS ONE, Daiana de Oliveira and Linda J. Keeling with the SLU department of animal environment and health in Uppsala, Sweden, wrote that it is "well known that behavior is influenced by the emotional state of the animal," and in recent years, there has been an increasing interest in how an animal's body posture might be an external indicator of emotion.

For their study, de Oliveira and Keeling mapped the body language of cows in three everyday situations: while eating, using a mechanical brush and queuing up for the milking robot, SLU said.

A principle component analysis of 3,700 observations of ear and head positions and tail behaviors in 72 cows from a single herd showed that body language in these situations was clearly different, the researchers said. Cows' body posture during feeding was ears back and neck down, with tail wags directed towards the body, they noted. During queuing, the cows' ears were mainly axial and forward, the neck below the horizontal and the tail hanging stationary. During brushing, the cows' ears were backwards and asymmetric, the neck horizontal and the tail wagging vigorously, de Oliveira and Keeling reported.

Placing these findings into an "arousal/valence framework" allows predictions of how these postures change in other situations previously demonstrated to vary in valence and arousal, the researchers said.

This could contribute to the identification and validation of behavioral indicators of how positively or negatively cows experience other activities or situations and how calm they are, de Oliveira and Keeling concluded.

The researchers noted that although developed on dairy cattle, this approach could be easily adapted to other species.

The open-access article -- "Routine Activities & Emotion in the Life of Dairy Cows: Integrating Body Language into an Affective State Framework" -- is available online.