Thermoregulation chapter 1

Why do we have housing?

Manipulation of:

* Reproduction
* Production
* Health/diseases

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Condition of:

* Climate
* Health/diseases

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Control of:

* Behaviour
* Feed
* Reproduction
* Longetivity

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But why?

* Increasing production
* Decreasing costs

With keeping consequences to 3rd parties in mind (animals, humans, environment).

Positive aspects of animal housing

Positive aspects are, among others, the supply of food and water and shelter against extreme climatic conditions.

Negative aspects of animal housing

Negative aspects appear particularly when the needs of animals are not (completely) met. In many cases, animal housing reduces the choices animals can make (e.g. can’t influence climate when in a barn via behaviour).

How to measure the influence of housing?

To measure this objectively, different characteristics can be determined, such as changes in:

* Hormone levels
* Fertility
* Disease resistance
* Behaviour
* Production/growth
* Heat production and heat loss

Homeostasis

the animal body’s attempt to maintain a constant and balanced internal environment.

Maintaining homeostasis

1) If the environment of the animal is changing, this is detected by a certain receptor (for example a temperature sensor in the skin or a CO2 sensor in the aorta).

2) The information of the receptor is compared with the set point of the central nervous system (especially the hypothalamus).

3) When those two deviate from each other, animals will react by adjusting their neural and/or endocrine system, whereby for example behaviour or metabolism will be changed.

Sometimes animals are not able to adjust properly. When the same stressor persists for a long period of time or reoccurs often, an animal will adapt to it and the specific stressor will no longer be perceived as such.

Acclimation

All reactions of an animal occurring after changing 1 specific environmental factor. For example, a chicken will acclimate to a change in day length.

Acclimatization

All reactions of an animal occurring after more complex changes in climate and/or housing conditions. The responses can be caused by several factors at the same time. For example, a dairy cow with outdoor access will acclimatize to weather changes, such as sun, wind, temperature, and day length.

Habituation

Adaptation to a repeated stimulus that is initially experienced as a stressor.

Energy reallocation

GEDEME

Maintenance

* Protein turnover
* Physical activity
* Circulation and respiration
* Thermoregulation
* Immunology
* Stress
* Digestibility

Performance

Meat, milk, eggs etc.

Energy reallocation

When a homeothermic animal is exposed to a cold stress for example, the animal will try to maintain its body temperature. It will increase its heat production and energy requirements towards maintenance. An increase in maintenance is required and occur at the expense of energy that is available for performance (e.g. production of milk). → Reallocation can also happen within maintenance!!!