Although behavior responses are usually easier to observe and more accessible to us, we mustn't ignore the fact that there are a variety of other measurements that could be used to provide us with information about how the animal is functioning. >> Both behavioral tests give us much more direct access to how an animal is experiencing its life. We can also use physiological measures of welfare because they provide an indirect measure of an animal's experience. >> There is a sequence that makes up an animal's overall experience. Firstly, the animal gets sensory input from the environment. Then the brain evaluates this information in relation to a number of factors, including the animals previous experiences. This process may lead to activation of the parts of the brain that control emotions causing a response that might be positive, or negative, or even neutral. The body responds to the emotion with behavioral and physiological responses. These reactions enable the animal to adapt to its environment, enabling it to return to normal, something that's called homeostasis. When faced with something that is quite a complicated internal response, welfare researchers have broken this down into the various components that relate to the animal's physiological response to a stressful situation. This is made up of an immediate response system sometimes called the flight or fight response to ensure that the animal is capable of escaping or attacking if need be to protect itself. As well as one that caters for the longer term requirements to maintain the response, and then to ensure the animal's body function returns to normal. Being on constant alert is an energetic business, and the sooner the animal can rectify the situation through it's behavior responses, the sooner the things can return to normal. >> Activation of the stress response occurs when an animal perceives something, we call that a stimulus as being of significance. Usually that's something that is frightened of or that's painful and is threat to it's well being. Immediately the body goes into protective mode and a coping mechanism is stimulated. The amygdala is an area of the brain where the animal's emotional centers are and a threat will cause a chain of brain chemical responses as a result of activation of the Sympathetic-Adrenal-Medullary Axis, sometimes called the SAM axis. Immediately, there will be a rise in the blood hormone called adrenaline, which will provide that energy burst needed to respond effectively. At the same time, there is a slower but more longer acting response being initiated in the part of the brain next to the amygdala, the hippocampus. The Hypothalmic Pituitary Adrenal axis, or HPA axis, controls reactions to stresses, and regulates many body processes, including digestion in the in function, and even mood. Activation of the HPA axis is associated with increases in hormones such as cortisol, which can be measured in an animal's blood, saliva and even feces. Measurements that can be made to see if the SAM axis has been activated include heart rate and heart rate variation. And this is often used in animal welfare studies as a way to very simply record immediate responses to changing situations within an animal's housing environment and in relation to handling by humans. Another measure of SAM activity is adrenaline. And although it requires multiple quick succession sampling, it can be useful for looking at the immediate consequences of painful situations such as the impact of branding on sheep. As can be seen from the graph, hot branding shown by the red bar leads to a much higher rise in adrenaline 30 seconds after the branding iron has been applied, as compared with the freeze branding that is no different from having no brand applied at all. Whilst useful, the use of measures of some axis activity for assessing animal welfare are limited because of the short term nature of the response, which is why the HPA axis measurements are useful. The HPA axis responds more slowly. For example it can take an average of around two to ten minutes, for a rise in the levels of cortisol in blood to be measurable. But this does mean that it's easier to measure, and to work out recovery over time. >> There are a number of events in an animal's life that can cause a stress response, but these are not all necessarily of welfare concern. Some may be positive emotional experiences and important for enabling the animal to learn. Humans often seek out experiences that cause a fear or stress response, such as the adrenaline surge associated with driving a fast car or even bungee jumping. Stress has only become a concern for animal welfare when the animal is being continually challenged and stressed beyond it's capacity to emotionally and physically cope. In turn this can cause changes within the immune system leading to increase disease susceptibility, poor growth, and reduced production. All of this results in animal suffering. >> When the HPA access is activated the result is a cascade of chemical responses in different parts of the animals brain and body that leads the pituitary gland to release a hormone called Adrenal Corticotropic hormone, which is ACTH. This in turn stimulates the adrenal glands to release circulating hormones, Glucocorticoids. The one that's most commonly measured in mammals is cortisol, and in birds, corticosterone. Measurements of cortisol can be made to identify the situations that cause a negative stress response by looking at levels in blood and also saliva, urine, feces, and even milk. Although sampling blood may not always be possible, sampling urine, milk, and saliva is relatively easy, and in general, noninvasive, providing a practical option that can be better for welfare. In this example, you can see the way cortisol differs in two environments where pigs are housed for giving birth. Sows in open pens with straw where they can build a nest had far lower cortisone levels, than those kept in farrowing pens on hard floors, with no possibility of building a nest. In order to use this method, samples need to be analyzed for cortisol concentration by a trained person. There are too main methods, and the one being used here is called the Eliza method. >> I'm Susan Richmond. I'm a PhD student here with SOEC and University of Edinborough and I'm in my third year and we're looking at new ways to assess the welfare of hill sheep. And Eliza is an enzyme linked to which we're using to look at the presence of in sheep feces. Then Eliza can be used for looking at the concentration of other substances and in other bodily fluids such as saliva, blood, urine and as well as the feces that we're using. We have a few methods that we're using, a few indicators that we're using to assess the sheep's welfare. And we have a variety of behavioral and physiological measures. And I'm using the for the physiological measure, for the assessment. We followed our protocol for the initial stages and now we're left with this plate, which has our sample, our antibodies attached to the wells, and also other chemicals in there, and we can put the plate into the plate reader to look at the concentration in the wells. The plate reader reads the plate and in a matter of seconds and this is one of the outputs that we get. You can see the graph and the values in the cells below. And we can see here that this graph here shows our standard curve and we do that to make sure that we can trust the results that we're getting from the plate. And because we have the same individuals on the one plate, and I can look at how that individual's changing over time. So across the seasons and gestation and also look if we have any other data on the animal, any other health problems, any leaveness and other behavioral measures to look at how these are changing as a whole throughout the whole picture of the animal. We can't just rely on this one measure to tell us everything we need to know about the animal. And as we been collecting a variety of behavioral measures along with and some other physiological measures. We have to look at cross validating these two things. So whether physiology is cross validated with the behaviour and vice versa. To build a more true picture of what the animal is really experiencing. >> There are a variety of different hormones and challenge tests, as well as immunological measures, that have now been developed. But none of them are without their limitations. These are mainly down to the problems with getting a sample without stressing the animal and influencing the situation. The need for laboratory facilities for analyzing the samples, and the challenge of interpreting what the results really mean for that animal. Measuring the animal's physiological stress response cannot tell us everything that we want to know about an animals experience, we also need behavioral measures, and in order to interpret the results we need to look at how the physiological measures relate to what the animal is doing. This is why animal welfare scientists use a battery of measures together to make sure that they have the best evidence for assessing the situation from the animal's point of view.
