If we are to ensure that animals have a good life, one which is rich with positive experiences, then we need to have reliable and practical animal-based measures for their emotional states. In our study, we aimed to determine the suitability of ear postures as indicators of a positive, low arousal emotional state in dairy cows. By conducting experimental stroking on 13 habituated cows we induced what is suggested to be a low arousal positive state. We conducted 370 fifteen minute focals, comprised of three segments: 5 minutes pre-stroking, 5 minutes stroking and 5 minutes post-stroking. We then recorded the duration of time each cow spent in four identified ear postures. Two of the postures were described as alert with tense muscles, and two were considered as relaxed with little to no muscular tension. 

We performed One-Way ANOVA repeated measures analyses and found that the two alert postures, EP1 and EP2, were performed for significantly longer during the pre and post-stroking conditions than during stroking (EP1; F(1,2) =241.22, p=0.00 & EP2; F(1,2) =39.09, p=0.00). The opposite was found for the relaxed ear postures EP3 and EP4, which were performed for significantly longer during stroking (EP3; F(1,2) =81.20, p=0.01 & EP4; F(1,2) =169.98, p=0.00). Furthermore, EP3 was performed for significantly longer during post-stroking than pre-stroking and EP1 for significantly less, suggesting a lasting positive effect (EP1; F(1,2) =241.22, p=.01 and (EP3; F(1, 2) =81.20, p=.01). 

We conclude that types of ear postures could be a useful indicator of positive emotional state in dairy cows. These results indicate that 'relaxed' ear postures are indicative of what is suggested to be a positive, low arousal emotional state in dairy cows. These results present a reliable and quick measure which could be incorporated into on-farm welfare assessments to measure and subsequently improve the emotional states of dairy cows.