Environmental Physiology

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Welcome to class! 

In today’s class, we will be talking about environmental physiology. Enjoy the class!

Environmental Physiology

CONTENT:    

• Definition
• Effect of changes in climate on growth, milk production and egg production

What is environmental physiology?

Environmental physiology refers to the effects of the environment on the growth and performance of farm animals. It is the study of the environment to the response of farm animals. The effects could be high or low. Moderation is the target for optimum growth and performance.

Climate

Climate refers to the atmospheric condition of a place over some time. It is marked by rainfall, wind, temperature, humidity, sunlight etc.

• Rainfall:

1. High rainfall increases pests like tsetse flies, and diseases
2. High rainfall causes chilling of young ones
3. High rainfall does favour rearing of dairy animals
4. Extremes of rainfall do not favour the growth of grasses for foods

Control of rainfall

1. Shelter
2. Rain break
3. Drainage channels
4. Building orientation

• Wind:

1. Wind aids the spread of air-borne diseases e.g. tuberculosis, and death eventually
2. Moderate wind velocity promotes good ventilation.
3. Scare animals producing an undesirable level of growth hormones.

Control of wind

1. Shelter
2. Windbreak
3. Openings
4. Building orientation

• Temperature:

1. High temperature causes a reduction in food intake; low temperature encourages more feed intake
2. High  temperature reduce spermatogenesis and libido in males
3. High temperature causes heat stress and reduced activity.
4. It may result in the death of animals; in adult animals e.g. birds, young animal e.g. chicks and production animals e.g. layers
5. It increases water intake in hot weather and reduces water intake in cold weather.
6. It is necessary for incubation of eggs
7. It lowers  yield e.g. lower egg production
8. It affects  product storage  period under high climatic condition
9. High temperature affects the young ones e.g. hatching of the egg is reduced.

Control of heat and temperature

1. Introduce fans or air conditioners to animal house.
2. Provide enough windows or opening for ventilation
3. Cover windows with cloth materials to conserve heat
4. Provide vents at the rooftops;
5. Use poor conductors of heat for roofing/ sun reflecting sheets or paint roof with reflecting colour e.g. white. Pens should also have ceiling boards under the roof
6. Use room heaters or lanterns to warm building when it is cold

• Relative humidity:

1. It is very important in physiological processes e.g. incubation.
2. High humidity compounds the stress.
3. Low humidity induces rapid water loss from animal body and thus increases their water intake
4. High humidity encourages the spread of diseases
5. High humidity causes the feed to grow moulds
6. Causes the chilling of young ones

Control of humidity

1. Fixing humidifiers or open trays filled with water to increase humidity
2. Allowing free ventilation when the humidity is high
3. Avoidance of spilling of water to reduce humidity or dampness e.g. in the poultry pen

• Light:

1. Controls egg-laying in hens
2. Duration of lighting controls the time spent at feeding which regulates growth and the rate of feathering, furring.
3. Direct light of high intensity causes stress to the eyes
4. Bright light makes the animals active e.g. birds
5. Light makes objects visible to animals’ eyes

Control of light

1. In short, daylight provides extra illumination
2. There should be openings to promote lighting e.g. use of wire meshing and glass as reasonable parts of building construction.
3. Cover up windows with a dark cloth to reduce light intensity.

Effect of changes in climate on growth

The effect of climate on growth could be economically positive or negative to the farmer in that if they are extreme (excessively hot or cold) animals will not eat well and thus not grow well or each more and still not grow well. Other instances include

1. Wind aids spread of disease
2. High rainfall causes more incidence and multiplication of Tsetse fly and other pests
3. High humidity favours mould growth in pens and also in the feed which could cause diseases

A favourable climate ceteris-paribus should give room for farmers to make optimum gain from their enterprise. To this end, farmers ought to keep things in check such as

1. Installing fans and air conditioners
2. Plan for good ventilation when constructing an animal house
3. Used building materials that are poor conductors of heat
4. Painting walls of animal house white to reflect sun rays
5. Construct farm houses east-west direction
6. Use mesh in place of a brick wall at some heights
7. Install humidifiers or open trays filled with water to increase or reduce humidity.

And try to control all they can to ensure their investment does not go to waste.

Effect of changes in climate on milk production

Excess sunlight brings about heat stress, high humidity favours the growth of pathogens, milk will spoil at a temperature higher than 37°C. All these causes reductions in milk yield

Effect of changes in climate on egg production

High temperature reduces shelf life for eggs, hatchability, feed intake, and decrease in the quantity of egg produced. Light length increases feeding time for birds which may not translate into extra yield.

Evaluation

1. What is environmental physiology?
2. Write short notes on the effect of changes in rainfall and wind on growth in farm animals.
3. State two air-borne diseases that affect farm animals.

General evaluation

1. Write short notes on the effect of changes in the following on physiological processes in farm animals a) Temperature b) Relative Humidity c) Light
2. State the ways to control rainfall and wind.

Reading assignment

• Environmental Physiology from Essential Agriculture by O.A. Iwena pages 292-294
• Answer the following questions from WAEC PAQ 2007 theory question 8 and 2000 theory question 7

Theory

1. Discuss briefly A. rainfall B. light C. temperature in relation to poultry production.
2. Write a short note on the effect of temperature on the brooding of chicks.

 

In our next class, we will be talking about Livestock Management (pig).  We hope you enjoyed the class.

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