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Eye white may indicate emotional state on a frustration—contentedness axis in dairy cows A.I. Sandem, B.O. Braastad, K.E. Boe. Presented by Saethra and Russell Psych 486, Winter 2012. http://www.youtube.com/watch?v=ErRHJlE4PGI. Introduction/Background.
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Eye white may indicate emotional state on a frustration—contentedness axis in dairy cowsA.I. Sandem, B.O. Braastad, K.E. Boe Presented by Saethra and Russell Psych 486, Winter 2012
Introduction/Background • Animal welfare is increasingly about more than simple physical well-being and instead focuses on the subjective feelings of animals • Historically, these subjective feelings have been identified as negative, relating to suffering, stress, and pain. • Very little information on pleasant feelings and positive welfare indicators, which is the aim of this paper.
Generally accepted negative welfare indicators, specifically in cows: stereotypies (tongue rolling, bar biting, licking of equipment), increased vocalizations, increased frequency of aggression. • Preliminarily, wide-open eyes may be an emotional indicator in cows. The unavoidable side effect of this opening is an increase in visible eye white.
Materials/animals • 24 randomly selected dairy cows, ages 2-6 years, group-housed with a tie stall system in a barn containing 66 other cows.
Cows are out on pasture May to September and fed 2 meals of 10-20kg grass silage (fermented grass) and four meals of 1.5-3kg concentrate the rest of the year. • This experiment was done during the winter, between 12/17/99 and 2/17/00.
Materials/Methods • Special feeding boxes were designed for this study and cows were habituated to a box for 2 days (5 feedings) before testing. • The boxes were wooden, rectangular, and measured approximately 30”L x 22”W x 6”D. • Positive stimulus: access to food when hungry • Negative stimulus: thwarted access to food • When the box was used for negative stimulus, it had a lid made of Plexiglas with 16 holes, allowing visual and olfactory cues but preventing access.
Methods • Food withheld for 7 hours before testing, then 12 cows were presented positive stimulus, 12 cows were presented negative stimulus (randomly assigned). • All of the animals were recorded for 6 minutes after introduction of the stimulus. • Observations were video-recorded.
Methods • Behaviors observed and recorded: • Vocalization • Tongue rolling • Aggressive behavior (butting, attempting to butt) • Head shaking • “Bouts” of any given activity were separated if any other behavior was demonstrated for at least 1 second.
Methods • Eye white was measured approximately once every minutes, with 6 measurements total for each animal. • Recorded images were frozen on screen and a ruler physically placed on the monitor. Fig. 1. Examples of eyes varying in their percentage of the white shown. Diameters used for measurement of percentage of white in the eye are demonstrated to the right.
Methods • Eye white controls obtained from same 24 cows, in the middle of the day, outside of the experimental situation, while standing and not eating. • Statistical analysis was performed. For at least one of these analyses, the 6 measurements for each individual were collapsed into an average for each individual.
Results The average outside of testing was 25% The same was observed just prior to testing. The positive group (allowed to eat food) demonstrated an average of 10%. The negative group (not allowed to eat) demonstrated an increase to 60%. A significant difference after 2 min.
Fig. 2. The percentage of white in the eyes of fed and food deprived cows during a 6 min test (mean±S.E.). The dotted line represents cows given food, while the continuous line represents the food deprived cows. Each observation was done within±30 s of every whole minute after start of feeding or deprivation. The straight, hatched line indicates the average percentage of white in the eye in a neutral situation, i.e. when no specific stimulus is introduced to the cow. ∗∗∗P<0.001, Wilcoxon two-sample test.
None of positive group displayed the observed behaviors. 11 of the 12 negative group cows displayed two or more of the behaviors. Only aggression was displayed by the majority and correlated with eye white percentage r=.85 P=.0005
Discussion “The results support the view that stereotypies and vocalizations may be indicators of poor welfare...(and).. the first reaction to uncomfortable situations.” Since groups were assigned randomly dominance does not explain the aggression. Head shaking in the absence of insects may be a displacement activity. The positive correlation between aggression and eye white suggests the same underlying emotion. They believe it is a frustration or stress reaction and that it opens the field of vision allowing the animal to take in more visual information and detect a solution to the problem.
The positive groups almost closed eyes can’t be explained by protective feeding because it occurred when cows were not in direct contact with the food. They suggest the amount of eye white displayed is a social cue that indicates positive vs. negative emotion.
Conclusion Deprived cows experience an eye white percentage spike. Cows allowed to eat experience a decrease from base line. This supports the idea that stereotypies and vocalizations are indicators of frustration and poor welfare. The aggressive eye white correlation makes eye white percentage significant and suggests an indicator of emotion in cattle.
Conclusion This research has demonstrated that there is a correlation between eye-white and aggression. The simplest interpretation is that similar to human surprise, cows eyes open wider to take in more visual stimuli during aggressive interactions.
Further Discussion/Issues • Lack of frustration equals contentedness? • Evolutionary reason to display positive emotionality? • Need to know individual animals. • “Consummatory face” or happy? • Better design for data collection possible?
