Environmental Physiology

Transcription

1 Environmental Physiology Dr. Ken Koelkebeck

2 Introduction to Environmental Physiology Slide 1 I m Ken Koelkebeck, in the Department of Animals Sciences. In this module we re going to examine environmental physiology and how it affects farm animals. Slide 2 Our learning objectives for this particular module are: we re going to discover how we use farm animals in our society; we re going to define and learn the definition of what environment means; and we re going to discover and learn about environmental factors that affect various physiological system in most farm animals. Page 1 of 5

3 Introduction to Environmental Physiology Slide 3 We use farm animals in several different ways. We use them for meat, for the production of milk and production of eggs. At the University we also use farm animals for research purposes. We also use farm animals as pleasure for example, horses. And we also use animals for companionship, like dogs and cats. Slide 4 What is physiology? Basically, if we defined physiology we would define it as such: any and all interactions going on in each body cell of the animal and complex body organs. There are several factors that interrelate to the physiological mechanism of farm animals. That is nutrition, genetics and environment. They all interact with each other of affect the physiology of farm animals. Page 2 of 5

4 Introduction to Environmental Physiology Slide 5 Now we ll discuss what is the environment and what are its affects on physiology. If we can define what environment it is the physical, it is the chemical and biological factors that surround an animal s body. So anything that surrounds the animals body, whether it be the feed in front of that animal, whether it be the temperature that the animal is in, or be the neighbors in the same pen. This is what we define as environment. Here are some examples that I have listed for environment: temperature differences; humidity, the amount of moisture in the air; light, whether it is on or off or very dim; sound, air speed, which is the same outside as wind speed; air pollutants, for example in a confined animals building you might have levels of carbon dioxide, carbon monoxide, those would be classified as air pollutants; ground pollutants such as water; confinement, how animals are confined in a cage or a pen; social density, basically the area of space that is allowed per animal; and lastly animals numbers, basically how many animals are in a pen or in a cage that interact with one another. Slide 6 The effects of the environment on physiology, I have listed several here and we ll go over each one. Behavior reactions the environment can affect different behavior reactions of animals. Changes in the Page 3 of 5

5 Introduction to Environmental Physiology environment can also affect disease problems for some animals. And changes in the environment can also affect reproductive problems. Finally, the environmental change can also affect very greatly the physiological reactions of each animal. Slide 7 Here are the physiological systems of farm animals. I have listed several here. They are not limited to this list, but I wanted to provide you a list of different physiological systems of farm animals and how they change in relationship to the environment. The digestive system, all animals have to eat. Reproductive system, propagation of the species. This is very important in relation to animal physiology. Respiratory systems, all animals breathe, so what they take in and what they expel. Oxygen coming in and CO2 going out, this is a physiological system. Metabolism, and it s related to the digestive system. In relationship to the feed that they produce they have to produce energy to keep themselves warm and that is related to metabolism. And growth, growth is also a physiological system, how an animal grows from day 1 up to adulthood. And finally the circulatory system. The pumping of the blood in the arteries and the veins for proper physiological manipulation of that animal being. This is just a short list of various physiological systems of farm animals. Page 4 of 5

6 Introduction to Environmental Physiology Slide 8 In summary, in this short module what we have talked about and discovered basically how we use farm animals in our society. We have actually learned the definition of environment. The environment contains a lot of individual components: temperature, humidity, light, social interactions. But we have learned the definition and have learned what factors the environment can effect in physiological systems in farm animals. That concludes this module. Page 5 of 5

7 Adaptation Slide 1 I m Ken Koelkebeck in the Department of Animal Sciences. In this particular module we re going to discuss adaptation, how animals adapt to different environments and what is involved. Slide 2 Our learning objectives for this module we re going to discuss different types of adaptation. We re also going to know the difference between acclimation, acclimatization, and habituation. And discuss those differences. Page 1 of 9

8 Adaptation Slide 3 Types of adaptation, I have listed several types her and we re going to discuss them in this order. Number one is environmental adaptation. Number two is genetic adaptation. Number three is what we call induced adaptation. Number four is natural adaptation. And finally domestic adaptation and physiological adaptations. We re going to discuss each and every one of these in relation to adaptation to farm animals. Slide 4 What is environmental adaptation? What are the things involved in that? Basically it is any functional it s some sort of function that the animal is doing structural characteristic of the animal, or behavioral trait that favors the animals survival or reproduction in any environment. Basically it is structure, function and behavior, all these three things are involved when discussing an animals survival in any particular environment. Page 2 of 9

9 Adaptation An example I listed here is body temperature. Body temperature is a fluctuating temperature regime of the animal on a daily and monthly basis. We re going to discuss this in relation to environmental temperature. A cold blooded animal for example like a snake. A snake is what we called a cold blooded animal and in order for that animal to thermoregulate its body temperature it has to get exposed to the sun or exposed to shade. So out in the desert when a snake come out on a cold winter day it gets a little bit warmer because of the sun beating down on itself. So it regulates the body temperature and it takes it in from the environment so it doesn t have any internal mechanism of regulating its own body temperature. That is a cold blooded animal. A warm blood animal which are most farm animals can regulate their body temperature when it is cold or when it s hot out. Except for those animals at the very beginning of life such as poultry and pigs. They can t regulate their body temperature, but in most cases farm animals are warm blooded, they can regulate their body temperature irrespective of what the environmental temperature is surrounding them. Slide 5 We re going to discuss genetic adaptation. An animal s heredity or its genetic makeup that determines their capacity to adapt. For example, you can t expect a Hereford cow to survive very well near the equator where it is very hot because it is a Northern climate animal. So an animals heredity will determine its capacity to adapt in the Northern Hemisphere where we have wide ranges in temperature for the most part. Over time we re talking thousands of years the genotype may change due to environmental stress. That is what we call survival of the fittest. Page 3 of 9

10 Adaptation Slide 6 What is induced adaptation? Basically, stress induces animals to adapt to a given situation. If you have animals that are under stress whether it be confinement stress, whether it be social stress, whether it be environmental stress we re trying to induce that animal to adapt. In other words we re giving it an outside influence, that is stress for that animal to adapt to a given situation. Now, animals must be genetically capable of adapting. In other words those animals must have the correct heredity and the correct genetic make up to adapt when we impose a particular stress on that animal to adapt to a given situation. Slide 7 Let s compare that with natural adaptation. What is natural adaptation? It is the result of adaptation favoring survival in particular environments, whether it be cold, whether it be hot, whether it be the season of the year. As an example, we look at seasonal breeding in calves. Basically producers want to have their calves born in the spring of the year, when the temperatures are getting warmer. It makes Page 4 of 9

11 Adaptation no sense to have those calves born in late fall or winter because of the cold weather; it s not good for their survival. So seasonal breeding. What we try to do is to have those calves born in the spring for natural survival. This is what we call natural adaptation. Slide 8 Now we ll talk about domestic adaptation. Domestic adaptation is inherent characteristics that allow for survival with human care. The producer or animal care taker is influencing characteristics of that animal where that animal will survive with human care. Selection traits based on human desired trait. An example I like to use here is selection for milk yield. A dairy producer will select cows from year to year based on their milk yield. It s senseless for a producer to pick a cow and use it for breeding purposes if that cow doesn t produce a lot of milk. The producer will pick a cow that will yield a lot of milk in a given year. So that is an example of what we call domestic adaptation, in other words we re selecting that trait based on our human desire trait, which is selection for milk yield. Slide 9 Physiological adaptation is an inherent capacity of animals to adjust its Page 5 of 9

12 Adaptation biological functions, in other words its physiological functions, and survive different environments. This is a pretty neat little example that I like to use. It is the kangaroo rat. The kangaroo rat lives out in the desert and has a physiological system where it can concentrate water from its urine through its kidneys to survive hot environments. Basically, out in the desert where rainfall is very minimal the kangaroo rat doesn t need to drink a lot of water during the day or even during the week. That rat, if it finds a water source, can physiologically extract the water from its urine for its body cells and survive. That s what we call physiological adaptation to the very hot environment. What is a stressful environment? A stressful environment is animals are forced or induced to go into physiological adaptation. That would be in our previous example like the hot desert environment for the kangaroo rat, that would be a stressful environment. And the animal, the kangaroo rat, would be forced to go through physiological adaptation in order to survive. Slide 10 Stress is an environmental situation that provokes the adaptive response. So for example, let s just talk about heat stress. The stressor in a heat stress situation is actually the temperature, the high temperature of the environment. The general word for that particular phase is heat stress. It can be chronic, in other words long term. You can have a very long, extended period of hot temperatures which effect farm animals. Or it can be acute a very short term, days or even hours, of heat stress or cold stress that effect farm animals. So stress is the whole situation. The stressor is the factor that provokes it. It can be chronic or acute. Page 6 of 9

13 Adaptation Slide 11 What is acclimation? Acclimation is change or adjustment in the rate of function in response to periods one period or several periods of a change in a single environmental factor. Our example is an animal will pant and or sweat slower or more efficiently the longer it is exposed to heat stress temperatures. An example I like to use here is poultry. Poultry do not have sweat glands. So poultry cannot sweat in order to cool themselves in hot temperatures, they must pant. They do this by taking in air and expelling air at a very raid rate, that is what panting is called. As the heat stress temperatures are applied for longer or effected those animals the more efficiently or slower those animals will pant. It can then survive hot temperature over a longer period of time. Slide 12 Let s compare acclimation to acclimatization. What is acclimatization? It is a change or adjustments in function in response to complex environmental changes. Here we re talking about seasons of the year, not just heat stress temperatures over a day or a week, but we re talking about season of the year. Page 7 of 9

14 Adaptation The example I like to use here is ewes, which is female sheep, will breed during the fall of the year. So they breed in short day length. From about June 22 until the third week of December the day length is actually getting shorter. And ewes will breed during the fall of the year which is a little bit backwards from other farm animals such as birds and other animals which mainly like to breed during the Spring time of the year when the day length is long or getting longer. So this is a result of acclimatization of ewes breeding during the Fall of the year or during short day length in relation to other animals. Slide 13 Let s compare those two with habituation. Basically, habituation is when an animal become habituated to a certain stimulus when it occurs over and over again. An example I like to use here is basically a herd of cattle that are out on the pasture and a plane flies over head at a very low altitude producing a lot of noise. When those cattle first hear that plane fly over they probably get very nervous, start to run and hide, will go into the forest and will get very excited. Now if that plane comes back over again the second day and the third day and the forth day, after the forth or fifth day those animals realize that noise that they hear is not going to hurt them. So they become habituated, in other words they become more comfortable with that sound. They don t get very excited if it happens over and over again so it becomes habituated to that stimulus, which is the noise, when it occurs over and over again. Page 8 of 9

15 Adaptation Slide 14 In summary, we have discussed the various different types of adaptation. We also have discussed the difference between acclimation, acclimatization and habituation. This concludes this particular module. Page 9 of 9

16 Animal Thermal Regulation Slide 1 I m Ken Koelkebeck in the Department of Animal Sciences. This particular module we re going to discuss animal thermal regulation. Page 1 of 8

17 Animal Thermal Regulation Slide 2 Our learning objectives for this module is we re going to discover how farm animals maintain a steady state of existence. What we mean by steady state and how that relates to animal thermal regulation. We re also going to discuss how several environmental factors effect thermal regulation for farm animals. Page 2 of 8

18 Animal Thermal Regulation Slide 3 What is homeostasis? Basically all animals are constantly trying functionally, structurally, and behaviorally to maintain homeostasis or a steady state. Homeostasis or steady state mean the same thing. All animals are trying to do this either functionally, structurally, or behaviorally. Animal physiological systems maintain a steady state. The example I like to use here is again body temperature, blood ph, water balance and heart rate for example. Body temperature over a days period of time it fluctuates. It goes down, it goes up. Blood ph probably maintains about the same level in most animals. Water balance if they are very healthy maintain the same percent water in their system. Heart rate is pretty consistent except when the animals get excited. These are examples of physiological systems that maintain a steady state. Page 3 of 8

19 Animal Thermal Regulation Slide 4 What is homeothermy? thermy relates to temperature. All warm blooded animals try to maintain constant internal body temperature. This is what we call homeothermy. So all warm blooded animals are trying to maintain a body temperature. For humans it is 98.6 throughout the day unless the individual is sick. For beef cattle it is about 98 to 100. For poultry it is about 107 to 108 degrees Fahrenheit. They have a higher body temperature. But those animals, along with other farm animals, are trying to maintain a constant internal body temperature. This basically is what keeps them alive. It goes up and down on a daily basis and the animal does things physiologically and behaviorally to maintain that internal body temperature. We call this homeothermy. Slide 5 What are some environmental factors effecting animal thermal regulation? What we mean by animal thermal regulation is how the animal maintains its constant body temperature throughout the day or throughout the week or the month, depending upon the environmental factor. Page 4 of 8

20 Animal Thermal Regulation Air temperature is probably one of the most important environmental factors that affects animal thermal regulation. When it s cold, when it s hot, animals have to sometimes do drastic things to maintain their internal body temperature. So air temperature is a very, very important factor. Air speed or wind speed, whether the animals are inside a building or outside on the pasture. That in combination with air temperature can make the animal feel like it is either warmer than it really is or colder than it really is, wind chill or heat effect. Air vapor pressure is relative humidity. Relative humidity is the amount of moisture that is in the air compared to what it could hold at 100% saturation. In other words when the air is 100% saturation it is usually raining. Air vapor pressure and relative humidity is pretty important and it is related to air temperature above because when it is hot and humid outside animals are probably under heat stress versus hot and very low relative humidity. So that has an important inner relationship between air temperature and air vapor pressure or relative humidity. Radiant temperature is affected or produced by the radiant waves of the sun. When an animal is standing out in the pasture and receives radiant waves from the sun it probably gets warm. That is what we call radiant temperature. Lastly, contact medium temperature. The animal might be standing in a pond and is cooling itself by the temperature of the water. Or animals are standing and touching one another. Or if an animal is lying on concrete surface or a surface with litter or bedding, that contact medium temperature will effect its internal thermal regulation, internal body temperature depending upon what it is. Slide 6 This picture shows piglets in a system where they are thermoregulating. This pipe actually has hot water that can flow through it where the animals can get close to the hot water pipe or farther away. So the animal can theromregulate its own body temperature by getting close to it or away from it if it has room to move away. So it is like a microenvironment for the pig itself. Page 5 of 8

21 Animal Thermal Regulation Slide 7 This picture shows young poultry, in particular these are turkey poults that are in a breeding situation. As I said, poultry basically cannot maintain their body temperature early on. They must be what we call brooded. In other words that pancake brooder there is providing a heat source for those birds and we re keeping them amongst that heat source so they can be very comfortable for their first weeks of life. This is what we call brooding of poultry. Slide 8 This particular picture shows cage layers in a system where they are exposed to probably a thermal neutral temperature. We try to keep it about 70 to 80 degrees inside that house. As you see there those birds in cages are pretty close together so they can gain heat from their neighbors in the pen. This actually shows a system where the air flow through there can maintain the environment for the laying hens. This is a particular system that we use in a commercial industry. Page 6 of 8

22 Animal Thermal Regulation Slide 9 This is a picture of shelter for cattle. This could be either in the winter time or in the summer time. If we have that shelter space for them they can get underneath there and take advantage of shade, if it is very, very warm outside. Of course if it is cold outside they can take advantage of that as well, go underneath there and be sheltered from rain, wind, snow and be more comfortable in that environment, whether it is cold or it is hot. Slide 10 Animal responses to heat stress. We re going to talk a little bit about control of thermal regulation. There are several issues discussing this. Number one, internal: tissue insulation can slow the blood flow to the skin. In other words if an animal is very fat, if there is fat tissue around the blood vessels this can slow the blood too and from the skin and actually keep the heat source within that animal for its internal body temperature. This is a particularly important in very, very cold climates. Page 7 of 8

23 Animal Thermal Regulation External thermal regulation. Most animals have some form of cover. Poultry have feathers, cattle have hair, other animals have fur. Basically, hair and feathers have little muscles on the ends of them, this can increase the cover depth. In other words it can trap air. So when a chicken is cold in its environment it will fluff up its feathers and this will trap air next to its skin. When it does this this is a system where the animal can be insulated from the cold temperature because of the air trapped underneath the feathers. Slide 11 In summary, we have discovered and learned how farm animals maintain a steady state of existence, in particular homeothermy how most animals regulate their body temperature to keep it constant. We have also discussed several environmental factors that affect thermal regulation for farm animals. This concludes this particular module. Page 8 of 8

24 Thermal Exchange Slide 1 I m Ken Koelkebeck in the Department of Animal Sciences. We re going to be discussing, in this particular module, thermal exchange in farm animals. Slide 2 Our learning objectives for this particular module: we are going to describe four forms of thermal exchange between an animal and its environment; we are also then going to define what is sensible and what is latent heat flow, and compare the two; and then we are going to describe two physiological cooling mechanisms used by farm animals. Page 1 of 6

25 Thermal Exchange Slide 3 The first thermal exchange is radiation. What radiation is the heat flow without the aid of a material medium. For example a cow standing in the sun, there is no wind, in other words the wind is 0 miles per hour. And the cow is not touching anything, the cow is not lying down on the ground, it s just standing in the sun, no wind and not touching anything. The radiant waves of the sun will impact its internal body temperature. This is what we call radiation. An animal will radiate to all its surfaces surrounding it and to its environment and vice versa. For example, chickens in cages. Basically, they will radiate to each other animal in that same cage. So it will put out radiant waves to its neighbor and will actually receive radiant waves from its neighbor as well. So it goes both ways. Slide 4 The second type of thermal exchange is what we call conduction. What is conduction? Basically conduction is heat flow based on contact. We re talking heat flow between the animal and actually what the animal is touching. In other words the temperature difference between the animal s skin and what Page 2 of 6

26 Thermal Exchange the animal is touching. It depends on several things. Number one, temperature of the objects. So first of all you have the temperature of the skin of the animal and if that animal is laying on a concrete surface that animal is probably exposed to a little bit cooler temperature than the air temperature. Or if that animal is leaning against another animal then it is probably a warmer temperature. So it depends on the temperature of the objects that are actually touching the animal, surface contact basically if the animal is either standing or if the animal is laying down there is more surface contact between the animals skin and a concrete floor than if an animal is standing up. Then thirdly is conductivity of the material. Material such as copper, such as metals conduct temperature a lot easier than say wood. If the animal is laying on a concrete floor there is a bedding material that will help insulate that animal. So it depends on the temperature of the objects, surface contact and conductivity of material. So I have listed several here animal uses of conduction. Number one, a cow standing in a pond. Typically on a warm summer day, even if the sun is shinning and the sun is very hot, cows will get into the pond and they get cool because the temperature of the water is usually cooler than the temperature of the air. So it actually helps cool itself if it stands neck deep in a pond. Pigs also use mud. They will wallow in the mud because they are trying to again cool themselves if they are in an outdoor situation. Birds will also get in a water bath. Of course they use it for drinking purposes, but they will also get in the water bath to kind of help cool themselves on a warm summer day. So just a couple of examples of animals using conduction. Slide 5 The third type of thermal exchange is what we call convection. What is convection? Basically convection is heat flow as the result of wind or air. If an animal is standing outside and the wind is blowing 20 miles an hour the animal is getting cool or warm by the air flowing over it. If the animal is inside a building we have air going in and out of the Page 3 of 6

27 Thermal Exchange building, the animals get cooled or warmed by that air. What we mean by convection is that the warm molecules of air which are next to the skin get more excited and they require more space. So those warm molecules dissipate from the surface of the skin, when they do that the animal gets cool, basically the skin temperature gets cooler. Air molecules will rise and leave the skin and are replaced by cooler air molecules as a result of the air blowing across the skin surface of that animal. So in effect that animal feels cooler because those warm air molecules leave and are replaced by cooler air molecules. An example of convection is wind, of course. And wind is what we call forced convection. Slide 6 The last type of thermal exchange is what we call evaporation. This is important for a lot of animals, in particular poultry, but as well as other farm animals. What is this? Evaporation is heat flow due to liquid molecules having enough energy to change from a liquid to a gas. When an animal is sweating in most farm animals compared to poultry which do not sweat those liquid molecules of sweat on the surface of the animal actually have enough energy, they get warm enough, that they change from a liquid to a gas. When they change from a liquid to a gas this makes the animal feel a little bit cooler. Page 4 of 6

28 Thermal Exchange Slide 7 Now we can lump these avenues of thermal exchange into several different categories. Number one is sensible heat flow. What do we mean by sensible heat flow between an animal and its environment? We can actually measure, take a thermometer and measure, the temperature of the skin surface of that animal. We can then measure the temperature of the concrete floor that it is laying on. Those temperature difference basically allow the animal to thermal regulate. So if the animal is laying on a cool concrete surface basically this well help take heat away from the animals skin and we can actually measure those two temperature extremes with a thermometer. So we would lump the categories of thermal exchange of conduction, convection and radiation together as far as a sensible heat flow transfer between the animal and its environment. We ll compare that with latent heat flow. Latent heat flow is evaporation and or sweating for animals that sweat. Basically the heat is lost or hidden, when those warm water molecules leave the surface of the skin. That is lost, it is hard to measure with a thermometer, but the effect of sweating for an animal in a very hot environment tends to help cool itself. You can t measure with a thermometer, but that is what we call latent heat flow. Slide 8 This is a slide showing the sweating and panting of various animals. At the top I ve listed humans. At the bottom we ve listed chickens. We have a camel, a horse, a cow, sheep, cat, dogs and pigs. The way I tried to illustrate here is that most animals including humans use a majority of their evaporation methods to cool themselves by sweating. Humans use basically 100% sweating mechanism to cool itself in a very warm environment. Camels use quite a bit, horses use quite a bit. A cow for example will use about 50% panting, in other words they will pant 50% of the time and also sweat 50% of the time in order to cool themselves in a very, very warm environment. Page 5 of 6

29 Thermal Exchange If we go down the list to chickens, poultry and chickens basically do not have sweat glands. So they are incapable of sweating to cool themselves in very, very hot temperatures. When chickens are exposed to very warm temperatures they pant. In other words they move air in and out of their lungs at a very raid rate. They take advantage of what we call evaporative cooling. The air goes by the trachea which is the moist lining of the windpipe and basically that helps the animal keep cool in a very warm environment if it is panting. So that is the list in order from humans down to chickens that use a combination of sweating and/or panting to cool themselves. Slide 9 So in summary, what we have talked about is: described four forms of thermal exchange between an animal and its environment radiation, conduction, convection, and evaporation. And we have defined what sensible thermal regulation is, and what latent heat flow is, and compared the two. And then finally, we have described two physiological cooling mechanisms used by most farm animals. That concludes this particular module. Page 6 of 6

30 Curve of Thermogenesis Slide 1 I m Ken Koelkebeck in the Department of Animal Sciences, University of Illinois at Urbana Champaign. This particular module we re going to discuss the curve of thermogenesis, what that means to animals in farm animal building and look at various aspects of what that actually entails. Slide 2 The learning objectives for this module are, we re going to learn about temperature ranges that most farm animals are commonly exposed to, that cold and hot temperature ranges. We re going to learn what these temperature ranges are called. Thirdly, we re going to discover how metabolic rate and we ll actually define that metabolic rate and heat production changes in response to extreme hot or cold temperatures. Page 1 of 17

31 Curve of Thermogenesis Slide 3 This is what we call the curve of thermogenesis. Let me describe the x and y axis on this particular graph. On the x axis, on the bottom axis, we have what we call effective environmental temperature. The left hand side is very, very cold temperatures. The right hand side is very, very hot. You see that I didn t actually put a temperature range on cold and hot. On the y axis is heat production. The animal basically produces more body heat to keep itself warm in a cold environment and so that goes from essentially zero on up. This is what we call metabolic rate. Metabolic rate is simply taking the feedstuff that the animal takes in and produces body heat within each individual body cell to keep its temperature at a homeothermy level. We ll go ahead and discuss each and every section of this curve of thermogenesis and what that means and how the animals feel in very cold and hot temperatures. Slide 4 In the temperature range that we call the thermal comfort zone, which is number one. This is also known as TCZ for short, which is thermal comfort zone. This is a very small temperature range where the animal s thermoregulatory effort Page 2 of 17

32 Curve of Thermogenesis is very minimal. Where the animals don t have to do very much work in order to maintain this normal body temperature, in this very, very short environmental temperature range. Slide 5 You see there that s listed on the x axis there as number one in red. That temperature range could be 5 degrees, could be 10, could be 15. It depends on the type of animal that we re talking about. Slide 6 Number two is what we call the thermoneutral zone. Thermoneutral zone is also called, TNZ. Essentially this is an environmental temperature range where metabolism is minimal. In other words, the body heat or metabolic rate in each individual body cell of the animal is basically at a minimal or basal level. This is a temperature range we call the thermoneutral zone. Page 3 of 17

33 Curve of Thermogenesis Slide 7 As you see there listed in red is the thermoneutral zone. If you look at the curved line starting on the left hand cold environmental temperature range on the top, it comes down and then it has a basal level or minimal level between 15 and 7 on that graph. This is the temperature range what we call thermoneutral zone, which is the minimal metabolic rate of a particular animal. Slide 8 Number three is what we call the cool zone. Essentially we define this as an environmental temperature range of behavior and physical thermal regulation. Animals will behaviorally try to make themselves warm. They will seek shelter in cool temperatures. They will get closer to one another to seek radiant heat energy from their neighbors in the pen or the cage. It is also a physical thermoregulation effort of the animal in the cool zone. Page 4 of 17

34 Curve of Thermogenesis Slide 9 This is indicated by the red number three. Again it is to the left of the thermal comfort zone, TCZ. Again it is a short temperature range where the animal regulates its body temperature in the cool zone. Slide 10 Number four on the thermogenesis graph is called the warm zone. Of course it is the opposite of cool. It is the environmental temperature range, again of behavior and physical thermal regulation. For examples, animals, poultry, pigs, horses, beef cattle, essentially will behaviorally try to keep themselves cool. They will get away from their neighbors in the pen. They might seek shade. Cattle out on the pasture might stand in a pond neck deep. In other words, keep themselves cool in this warm zone. So they do this behaviorally and physical. Page 5 of 17

35 Curve of Thermogenesis Slide 11 On the graph of thermogenesis we see that the warm zone is to the right of the thermal comfort zone. Here again it is a temperature range where the animal is at a warm temperature, we don t really care what it is, but for different species of farm animals it will be different. The animal does things physically, does things behaviorally to keep its normal body temperature within an acceptable range in the warm zone. Slide 12 Number five is what we call hypothermy, remember thermy represents body temperature or temperature, hypomeans below. So essentially what is happening here is that the animals body temperature is decreasing or going down. This occurs when the animal is exposed to an extremely cold temperature and we ll see that on the graph here in just a minute. Page 6 of 17

36 Curve of Thermogenesis Slide 13 Number five is on the very left hand side of the graph up at the top. You can see there that that dotted line going all the way across is the animal s body temperature. At number five this is a very cold temperature where the animal just can t maintain its normal body temperature whether it be a human being of 98.6 degrees Fahrenheit, a cow which is about 99 degrees Fahrenheit, or a chicken which is about 107 to 108 degrees body temperature. It gets just extremely cold so that animal can t physically and behaviorally keep itself warm. Essentially what happens at number five the animal dies of cold stress. Slide 14 Number six on that graph is what we call summit metabolism. Summit of course is the peak of something, peak of the mountain. Essentially it is the peak of metabolic rate. This is the highest metabolic rate that the animal can produce. In other words the animal, when it is consuming feed and converting that heat energy in each individual body cell to keep its normal body temperature, is at its metabolic rate highest capacity. We ll see this on the graph. Page 7 of 17

37 Curve of Thermogenesis Slide 15 Number six, you see that the metabolic rate is the solid curved line going across the graph. It is at its highest level. We notice that it is at a very cold temperature range or cold temperature point. It could be say 25 degrees Fahrenheit for a beef cow out in pasture. Essentially it is trying to keep itself warm. Its metabolism is churning at its highest level to maintain its normal body temperature. Slide 16 Number seven is what we call upper critical temperature. What does this mean? Upper critical temperature is a temperature prior to increasing metabolic rate. It is on the right hand side of the warm zone and we ll see this in just a minute. Page 8 of 17

38 Curve of Thermogenesis Slide 17 As you see, number seven is actually indicated by a certain temperature. This is prior to increasing metabolic rate, and we ll discuss why that happens. This is a temperature where there d be 85 degrees Fahrenheit whether it be 90, but metabolic rate is going to increase after that, so it is a point on the temperature scale where this happens. Slide 18 Number eight is what we call basal metabolic rate. What this means is it is the metabolic rate at which it is at its lowest levels. It s going to be constant and the metabolic rate is at its lowest level. Page 9 of 17

39 Curve of Thermogenesis Slide 19 Here we see that whatever that level is for that animal to maintain normal body temperature is at its lowest level. It continues there at number 15, which we ll discuss in a minute, all the way up to upper critical temperature. This is what we call basal metabolic rate. It is metabolism at its lowest level. Slide 20 Number nine is what we call intolerable cold zone. This is a temperature range where it is very, very cold for animals. It is the environmental temperature range below which metabolic rate can no longer increase. We ll see this here in just a minute. Page 10 of 17

40 Curve of Thermogenesis Slide 21 You see number nine, basically is the temperature range of very cold temperatures that could be zero to ten degrees Fahrenheit; it depends upon the animal that we re talking about. It is basically where metabolism will go down, but it is a temperature range of whatever temperature causes the animal to die of cold stress, up to summit metabolism. So this is what we call intolerable, the animal just can t tolerate it anymore and succumbs to cold stress. Slide 22 Number ten is what we call the cold zone. Essentially this is an environmental temperature range of chemical thermal regulation. This is really where metabolism increases from its basal level up to summit metabolism. This is also what we call the area of cold stress. Page 11 of 17

41 Curve of Thermogenesis Slide 23 There we see number ten, which is a very large and wide environmental temperature range from the end of the cool zone to the beginning of the intolerable cold zone that is what we call the cold zone. Essentially what is happening here is that the animal is increasing metabolic rate from a basal level up to summit metabolism. So it is internally trying to produce enough body heat during this cold temperature range, it might be 30 or 40 degrees, but its body temperature can be stable because its chemically producing heat in its body to survive in what we call cold stress. Slide 24 Number eleven is what we call the hot zone. Basically this is the opposite of cold. This is the area of heat that we call heat stress. It is very, very important for a lot of our farm animals. This is where evaporative heat loss is the greatest. Animals pant or sweat in order to maintain themselves comfortable in the hot zone. This is a very dangerous temperature for animals and it is actually what we call the area of heat stress. Page 12 of 17

42 Curve of Thermogenesis Slide 25 We see this number eleven on the graph. Metabolic rate is increasing here. It is a shorter temperature range than cold stress, but here is where animals use evaporative cooling to maintain themselves cool. In other words to keep the body temperature from going up during the area of heat stress in the hot zone. Slide 26 What s number twelve? Number twelve, of course, is going to be the opposite of intolerable cold zone, it is the intolerable hot zone. This is the environmental temperature range where the animal just can t cool itself any longer. It s panted at a maximum rate, it has sweat at a maximum rate and essentially it just is too hot that the animal can t maintain its body temperature in a normal range and this is a very dangerous temperature range for most farm animals. Page 13 of 17

43 Curve of Thermogenesis Slide 27 Here we see it on the curve of thermogenesis number twelve to the right of eleven. This is where the animal is just trying to hopefully survive, but essentially what happens is it just succumbs to heat stress and will eventually die. Slide 28 This is what we call hyperthermy. The opposite of hypothermy. Where the animal is body temperature starts to increase in the intolerable heat zone. Page 14 of 17

44 Curve of Thermogenesis Slide 29 Number thirteen on the right of the graph at the very top. We see that the animals body temperature spirals up and just a tick of about three or four degrees rise in animals body temperature, would result in basically heat stress, death because the animal simply can t cool itself any longer. Slide 30 Number fourteen is basically line regarding animals body temperature. That is the dashed line all the way across. So on the left hand side as we talked about before is hypothermy and on the right hand side we talked about it just recent is hyperthermy, where body temperature goes up. So the animals constantly trying to maintain that normal body temperature throughout the temperature ranges, environmental temperature ranges, as we just discussed. Page 15 of 17

45 Curve of Thermogenesis Slide 31 Number fifteen, finally, is what we call the lower critical temperature. This is the lowest temperature prior to increasing metabolic rate. Prior to increasing metabolic rate the animal is trying to maintain its normal body temperature, but if it gets any colder than that the animal starts to chemically produce higher metabolism, which produces more body heat for itself. Slide 32 On the graph we see there number fifteen, lower critical temperature. Again that could be 50 degrees Fahrenheit, it could be 40, it could be 60. It kind of depends upon the animal species that we're talking about. Page 16 of 17

46 Curve of Thermogenesis Slide 33 To sum it all up for the curve of thermogenesis what we have learned about is temperature ranges of farm animals and what they are commonly exposed to. We have also learned what they are called. And also we have discovered how metabolic rate, in other words heat production, for each individual animal changes in response to extreme cold or extreme hot temperatures. This concludes this particular module. Page 17 of 17

47 Animal Response to Temperature Slide 1 I m Ken Koelkebeck in the Department of Animal Sciences, University of Illinois at Urbana Champaign. In this particular module we re going to discuss farm animal responses to temperature. Slide 2 Our learning objectives for this module is number one, to learn how farm animals thermal regulate in cold, cool, warm, and very hot temperatures. Number two, we re going to discuss the changes that occur in animals exposed to the cold and thermoneutral zones. And we re also going to discuss and learn about how sheep and swine, two species of farm animals, react to heat stress temperatures. Page 1 of 10

48 Animal Response to Temperature Slide 3 As we discussed in the curve of thermogenesis module, this is what we call the curve of thermogenesis. It is essentially the animals responses to the effective environmental temperatures ranging from cold to hot. And its increase in metabolic rate and or heat production. And how the animal maintains normal body temperature throughout most of the ranges of cold and hot environmental temperatures. Slide 4 The areas on the curve of thermogenesis are number one, the cold zone. We want to discuss several differences between the cold zone and the hot zone. As was seen on the graph, the cold zone is wider, in other words it is a larger or wider temperature range than the hot zone. Why is this? This is because heat stress, for most farm animals, is more difficult for them to manage. In other words they have to pant and or sweat to maintain themselves cool during hot environmental temperatures, which we d call the hot zone or the area of heat stress. Page 2 of 10

49 Animal Response to Temperature In the cold zone the animals can do a lot of things, and can withstand a lot wider range of cold temperatures. They can actually seek shelter. They can produce a lot of metabolism or metabolic rate can go up producing body temperature. Increasing body temperatures so they can withstand cold temperatures better than they can hot temperatures. What happens then in the thermal neutral zone on a curve of thermogenesis is three things. Basically it can shift with acclimation, when the animal acclimated to an environmental temperature, whether it be hot or cold, this thermoneutral zone can go up, towards the hot end, or down towards the cold end. In other words, they become more acclimated to a hot temperature if they re exposed to that for any length of period of time. So this thermoneutral zone can actually shift. Number two, the thermoneutral zone can vary with species of animals. Take for example cows, take a Hereford for example, which is comfortable in Northern part of the climate or a Brahman cow, which is comfortable in Southern or hot climate. They re both cattle, but it actually varies with the species and their thermoneutral zone is actually different for those two species of cattle. Thirdly, it can also it can also vary with the age of the animal. In poultry and pigs they need to be brooded at a very young age for the first several weeks of life. So their thermoneutral zone is way on the hot end of the curve of thermogenesis. As they get older, as they get larger, as poultry actually get feathers on them that thermoneutral zone will shift and go down towards the cold end of the curve of thermogenesis. It will vary with the age of that animal. Slide 5 How do we keep animals comfortable in some of our building and environments depending upon the cold and hot temperatures. This is just a picture showing ventilation controls and temperature ranges in a particular building. They re very, very complex now than what they used to be, twenty or thirty years ago. Page 3 of 10

50 Animal Response to Temperature We use static pressure. We use the difference between the outside and inside temperatures. We use how many animals are in the building to maintain ventilation rates to keep animals comfortable in very cold and very hot environments. Slide 6 This particular picture is in the swine building, where what we do is try to distribute the air evenly for each individual pig in that building. This is what we call an air tube. It s a positive pressure system, air is coming out of those holes and actually mixes with room air in there and will distribute the air evenly so that each individual sow is very comfortable in that environment. Slide 7 This is a picture of a dairy free stall system, where we use natural ventilation. Whether it is cold or hot outside the louvers or spaces on the right hand side of that building that are open partially, which allows air currents to convectively mix with one another inside that building to keep those cows comfortable. Page 4 of 10

51 Animal Response to Temperature Slide 8 We re going to talk about thermal regulation in the cool zone. What happening here is the animal physically and behaviorally, but behavioral is most of the effort involved in thermal regulation in the cool zone. The animal seeks warm places, tries to get next to its buddy in the cage or pen, to behaviorally get warm in that particular situation. What also happens is we have an increase in insulation. For cattle, for example the hair cover of cows and cattle, basically in the Fall and the Winter time of the year gets heavier and thicker so that those animals can withstand very cold temperatures. What poultry do is they often fluff their feathers. In other words, when they re in the cool zone they feel that they re cool and what they ll do is fluff their feathers. They [the feathers] get away from the animals skin and this tends to trap air to keep themselves warm. Animals will most often seek warm places again in the cool zone. Slide 9 Now, we ll discuss what s going on as far as thermal regulation in the cold zone, the cold zone is to the left of the cool zone on the curve of thermogenesis. This is where animals increases Page 5 of 10

52 Animal Response to Temperature metabolic rate. When the animal increases metabolic rate from basal metabolism all the way up to summit metabolism, this produces body heat for the animal. This is what we also call the zone of chemical thermogenesis. It s chemical because there are more chemical reactions occurring in each individual body cell as the animal produces body heat through the metabolism of feedstuffs. Animals also increase shivering. This is a mechanism where the muscles move very rapidly and this helps to drive the chemical thermogenesis and helps to drive and increase metabolism itself. The animal is also more active in the cold zone, where they increase voluntary muscle movement. If they move around a lot more this will help to drive metabolism. Slide 10 Let s talk a little bit about thermal regulation in the warm zone. The warm zone is the right of the thermoneutral zone. Animals in the warm zone will basically voluntary decrease feed intake. The more feed that they consume, of course metabolism will rise. The animal does not want metabolism to rise, but it does start a little bit in the warm zone. The animal will actually decrease feed intake. This is an area or zone of behavioral thermal regulation. They will actually try to make themselves cool in a warm zone. They also increase passive heat loss, behaviorally. In other words, they will try to get way from their neighbors in the pen or the cage, they will try to seek a little bit cooler areas in their environment in the warm zone. The will also increase peripheral circulation, where the blood actually starts to flow a little bit stronger towards the limbs and the feet and the legs of their body. So they increase peripheral circulation to help them maintain normal body temperature in the warm zone. Page 6 of 10

53 Animal Response to Temperature Slide 11 Let s compare that to thermal regulation in the hot zone, to the right of the warm zone. This is where, again the animals use the greatest use of evaporative heat loss. Evaporative heat loss is animals that are sweating and/or panting. In other words, for poultry it is panting and for most other farm animals it is a combination of sweating and panting to make themselves cool, to keep themselves cool, in the hot zone. Also what happens is animals voluntarily reduce body movement. In other words if you go into a poultry house in the hot zone in a very, very warm temperature, the bird inside the house will be moving around very, very little because when they move around a lot of course remember this means it increases metabolic rate, which they don t want to do. So they reduce their body movement to save energy and not to voluntarily drive metabolic rate up, which is counter productive in the hot zone. Also on the curve of thermogenesis we notice that there was an increase in the basal metabolic rate. Why does this actually occur? Well this occurs because the animal uses increased energy used to pant and or sweat and to get cool forces the metabolism to increase. So metabolic rate has to go up when the animal tries to pant and tries to cool itself in the hot zone. We don t want this to happen, but it happens and this is why the hot zone is very, very stressful temperature for most farm animals. Page 7 of 10

54 Animal Response to Temperature Slide 12 What about cold stress, what happens in the area of cold stress? We have two responses. Number one, of course is the non shivering response. Again this is where an increase in metabolic rate occurs in the body tissues. Metabolism is getting greater in each individual body cell, in other words the animal is producing more heat through metabolism. This is what we call the non shivering response. Secondly, this is the shivering response. This is when metabolism increases and the muscles contract and they move around quite a bit. Which helps to drive metabolism. So number two the shivering response helps to drive an increase in metabolic rate to keep animals normal body temperature during the area of cold stress. Slide 13 Let s talk about a couple of example of the effect of environmental temperatures and we re going to talk about heat stress on sheep reproduction. What occurs in sheep is something that is called fetal dwarfing. What fetal dwarfing is are lambs that are born in hot weather. In other words, if it is very, very hot, for example, when Page 8 of 10

55 Animal Response to Temperature the lambs are born basically they are small. Why are they small? Basically, it is the quality of the nutrition for the ewe, or its mother, has decreased. Basically, the quality of pasture out there that the ewe is on, heat stress grasses and when they graze on that this causes an imbalance and physiological stress on the ewe. If lambs are born during hot weather, they will be smaller than normal for this particular species. Slide 14 How about heat stress in sows. What happens in heat stress temperatures for sows? Heat stress, before and at the time of mating, reduces estrus behavior. This is the willingness of the sow and the boar to breed naturally. It reduces their want to breed during heat stress if it occurs before or at the time of mating. What also happens is that heat stress does not reduce the ovulation rate. In other words, the number of piglets that one sow can farrow. The ovulation rate is not reduced, but estrus behavior is. Heat stress during two weeks following actual farrowing of piglets will reduce embryonic survival. So the piglets that are born in a very, very hot temperature even though they have to be brooded, this will tend to reduce embryonic survival for this particular species. Page 9 of 10