Environmental Physiology SS2 Agricultural Science Lesson Note

Environmental physiology refers to the effects of the environment on the growth and performance of farm animals. It is the study of the environment about 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.

i. Rainfall

Effects of rainfall are:

i. High rainfall increases pests like tsetse flies and diseases                                                                                                   ii. ii.  High rainfall causes chilling of young ones

iii. High rainfall does favour the rearing of dairy animals

iv. Extremes of rainfall do not favour the growth of grasses for foods

Control Of Rainfall

i. Shelter

ii. Rain break

iii. Drainage channels

iv. Building orientation

2. Wind

the instrument used to measure wind 

Effects of wind include:

i. Wind aids the spread of air-borne diseases e.g. tuberculosis; and death eventually.

ii. Moderate wind velocity promotes good ventilation.

iii. Scares animals producing undesirable levels of growth hormones.

Control Of Wind

i. Shelter

ii. Windbreak

iii. Openings

iv. Building orientation

3. Temperature: Effects are temperature are:

i. High temperature causes a reduction in food intake; low temperature encourages more feed intake.

ii. High temperature reduces spermatogenesis and libido in males

iii. High temperature causes heat stress and reduced activity.

iv. It may result in the death of animals; in adult animals e.g birds, young animals e.g chicks and in production animals e.g layers

v. It increases water intake in hot weather and reduces water intake in cold weather.

vi. It is necessary for incubation of eggs

vii. It lowers yield e.g. lower egg production

viii. It affects product storage  period under high climatic conditions

ix. High temperature affects the young ones e.g. hatching of eggs is reduced.

 an instrument for measuring temperature 

Control Of Heat And Temperature

i. Introduce fans or air conditioners to animal houses.

ii. Provide enough windows or openings for ventilation

iii. Cover windows with cloth materials to conserve heat

iv. Provide vents at the rooftops;

v. Use poor conductors of heat for roofing/sun-reflecting sheets or paint the roof with a reflecting colour e.g. white. Pens should also have ceiling boards under the roof

vi. Use room heaters or lanterns to warm the building when it is cold

4. Relative Humidity

instrument for measuring humidity (hygrometer)

i. It is very important in physiological processes e.g. incubation.

ii. High humidity compounds stress.

iii. Low humidity induces rapid water loss from animal bodies and thus  increases their water intake

iv. High humidity encourages the spread of diseases

v. High humidity causes feeds to go mouldy

vi. Causes chilling of young ones

Control Of Humidity

i. Fixing humidifiers or open trays filled with water to increase humidity

ii. Allowing free ventilation when the humidity is high

iii. Avoidance spilling of water to reduce humidity or dampness e.g. in the poultry house

5. Light 

i. Controls egg laying in hens

ii. Duration of lightning controls time spent at feeding which regulates growth and the rate of feathering, and furring.

iii. Direct light of high intensity causes stress to the eyes

iv. Bright light makes the animals active e.g. birds

v. Light makes objects visible to animals’ eyes

Control Of Light

i. In short daylight, provide extra illumination

ii. There should be openings to promote lighting e.g. use of wire meshing and glass as reasonable parts of building construction.

iii. Cover up windows with 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 more and still not grow well. Other instances include:

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

A favourable climate should give room for farmers to make optimum gains 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 farmhouses in an east-west direction
6. Use mesh in place of brick walls at some heights
7. Install humidifiers or open trays filled with water to increase or reduce humidity.
8. 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, and milk will spoil at a temperature higher than 37°C. All these cause a reduction in milk yield

EFFECT OF CHANGES IN CLIMATE ON EGG PRODUCTION

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

ASSIGNMENT

1. The instrument used to measure the relative humidity is A.thermometer B.anemometer C.hygrometer D.hydrometer
2. Which of the climate factors is likely to have the greatest effect on animal production in Nigeria? temperature air movement C. rainfall pressure
3. The factors that can predispose animals to diseases include the following except poor housing B. malnutrition C. immunity D. physical injuries

4. The effects of high environmental temperature on dairy cows include the following except fever high feed intake high water intake low milk production

5. The equatorial rainforest belt is not usually used for cattle production because of the low relative humidity absence of  natural grasslands C.incidence of Tsetse flies  D.dense vegetation