The Use of Traditional Fear Tests to Evaluate Different Emotional Circuits in Cattle

Here, we present a protocol to conduct a variety of behavioral tests in cattle that have been designed to evaluate emotions. A battery of behavioral tests (open field test, startle test, bovine zero maze, exit velocity, pen score, and chute score) were conducted to evaluate different components of animal temperament.

Transcript

Okay, we've discussed how these different scoring systems are getting different data, and you've done really nice statistics and cluster analysis to show how this is working, and it'd be really good to explain it for everybody out there that's watching.Sure. On how this works and explain it in an accessible manner. Yeah, we measured all of these different behavioral responses of these animals in different scenarios and, that were designed to elicit specific emotions, so we looked at exit velocity, so how quickly is the animal leaving the chute after it's been handled, and so you can have a number with that.

With the chute score, you're looking at how strongly they respond or pull to being restrained in the chute. And they struggle. Yeah, and they struggle.

And so there's a scoring system that we've used for decades, that you can give them a one to five score with this. There's also the pen scoring system, where you can stick them in a pen with a couple of their conspecifics. Someone walks into the pen, and you can move them around, and there, again, is a scoring system available for recording how this animal responds to the person moving them in the pen.

Then we also said, okay, let's look at some of the other temperament tests that are used in different scientific arenas, and so we looked a little bit at some of the biomedical research, and so some of the tests that they do in biomedical research include an open field test, where it's just an open pen and you stick the animal in there and you let it explore, and then we just record what the animal does, and some of them stay close to the side, some of them explore out into the middle. We're looking at how bold or exploratory or willingness they are to look at their environment. That's probably a lot of seek trait there.

Yeah, and I think there's a lot of seek going on there. The other tests that we looked at was we modified the elevated zero maze that's typically used in biomedical research to look at the efficacy of anti-anxiety drugs. And so we made one that's cattle-sized.

So we thought, well, let's just see how they behave in this and how the behavior that happens in the bovine zero maze, the open field test, the pen score, the chute score, and the exit velocity, how do they all kind of cluster together? The other test that we ran was also a startle test where we put the animal in a pen and then we open an umbrella in its face, like. Like that.

So the idea is kind of scare it, and then we can quantify the behavior associated with that startling event. Aiming to identify an efficient way of behaviorally evaluating the different emotional circuits, and to better understand the traditional temperament tests, a variable reduction for modeling cluster analysis that's traditionally used to meet marketing and business needs was performed. The number of steps in the open field test, individual startle test, group startle test, and bovine zero maze, along with exit velocity, pen score, chute score, and average daily gain, were analyzed with the goal of minimizing the number of behavioral metrics needed to conduct a comprehensive evaluation of cattle temperament, and to identify any relationships between the contextual behavioral responses and productivity.

The cluster analysis identified groups of variables that are as correlated as possible among themselves, and as uncorrelated as possible with variables in other clusters. The algorithm starts with all variables in a single cluster, and once the second highest eigenvalue in the cluster reaches the dominance threshold, the cluster is split. This process is repeated until the value is set at the default value of one.

Demonstrating the procedure will be Amanda Hubbard, a doctoral student from our laboratory. To test the exit velocity response, place electronic timers in front of a handling chute so that the distance between the starting and stopping points is 1.8 meters. When the timers are in place, move the cattle through the handling facility, and restrain each animal individually in the head gate of the chute for 10 seconds.

When the animal has been released, use the timers to record the time it takes for the animal to traverse the 1.8 meters out of the chute. To determine the chute score, catch each animal in the head gate of the chute for 10 seconds without applying pressure to its body, and observe the animal to score the behavior while being restrained, according to the 2019 Beef Improvement Federation Guidelines for Uniform Beef Improvement Programs, Ninth Edition. At the end of the observation period, release the animal from the head gate and chute.

To assess the pen score, place five cattle in a 7.3 by 7.3 by 2.4 meter pen, and have a single human observer that is unknown to the cattle enter the pen on foot and close the gate after entering. Have the observer take two steps toward the group of cattle and visually monitor each animal's behavior in response to the observer, assigning a behavioral score to each animal within 30 seconds of the observer entering the pen. To perform a bovine zero maze test, first, construct a 1.6-meter wide circular track with a 6.6-meter inner diameter, and an 8.2-meter outer diameter.

And mount video cameras to capture the entire arena. When the maze is ready, using low stress handling practices, move a single animal into an open portion of the maze, and allow the animal to explore the arena for 10 minutes. At the end of the exploration period, return the animal to its home pen, and decode the video recordings for the indicated behaviors.

For individual and group startle tests, place umbrellas that can be opened suddenly at the push of a button on opposing sides of the animal pen. For an individual startle test, using low stress handling practices, move a single animal into the testing arena. For a group startle test, introduce a group of approximately four animals.

After the animals have been in the arena for 60 seconds, open the two umbrellas simultaneously. Then leave the animals in the arena for four minutes before returning them to their home pens, and decode the videos of their behavior according to the table. To perform an open field test, use a low stress handling practices to move a single animal to the center of the animal pen, and leave the animal alone in the arena for 10 minutes, before returning the animal to its home pen.

Then decode the videos of the animal's behavior using the same criteria as for the startle tests. In these representative experiments, the growth rate increased, and the exit velocity and pen score decreased. No relationship was observed between the growth rate and the chute score.

A positive relationship was observed between the pen score and the exit velocity. No relationship was observed between the chute score and the exit velocity, or between the chute and pen scores. The cluster analyses identified three primary clusters in the data.

The number of steps in the group startle test clustered with the growth rate and the exit velocity. Since the cattle in the group startle test were evaluated in groups, the additional stressor of social isolation was absent during the evaluation. Because of that, they may have been able to express an honest signal of fear once they were not experiencing the social isolation-induced, panic/seeking stress.

This pattern suggests that the dominant emotional response was influenced by the context in which they were evaluated. The number of steps in the bovine zero maze, open field test, and individual startle test clustered together. The pen score test clustered with the number of steps in the open field test, bovine zero maze, and individual startle test, all three tests that can simulate the panic/seeking response due to the social isolation required during this test.

Since pen score is much easier to collect compared to the open field test, bovine zero maze, and individual startle test, the pen score may be a prudent test for evaluating the panic/seeking response. The chute score, however, did not cluster with any of the other variables. Instead of trying to look at singular relationships between chute score and pen score, we decided to take all of the variables and put them together kind of in a cluster, and so what we were able to figure out, there's a lot of relationships between growth and exit velocity, and there's also a lot of relationships between growth, exit velocity, and the behavior in the startle test when they're evaluated as a group.

We noticed that the data associated with chute score, which we think is associated with rage, that didn't cluster with anything else, so it just really kind of stood on by itself, and it really didn't have any strong relationships with any of the other parameters that we measured in any of the other tests. One of the comments I wanna make, in looking at literature on this, on exit speed, how fast they come out, and you measure that electronically, how much they struggle in the squeeze chute, those things started to diverge about 10 years ago. You see now, we'd already been 15 years into selecting for low fear cattle.

Oh, interesting, yeah, so you can definitely make some breeding selection choices that will influence how they behave in these different tests. If you're actually gonna use these tests, you need to get some practice cattle that will not be in your study, because you've got to get a lot of people coordinated to do these tests, and practice with just some practice cattle to learn how to do the tests before you actually get your experimental cattle and test them, because you can't practice with them, because then they would learn. Yeah, and the animals, they do things you never imagine.

So stuff like one steer put its head to the side of the maze and walked off with the maze. So you have to kind of troubleshoot some of these things so that when you're actually ready to do the data collection itself, you've hopefully addressed some of this stuff, with those that you're not gonna get data from.

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Journal (Behavior)

Journal (Behavior)

The Use of Traditional Fear Tests to Evaluate Different Emotional Circuits in Cattle

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