SUBJECT: AGRICULTURAL SCIENCE
CLASS: SS1
DATE:
TERM: 3RD TERM
REFERENCES
- Essential Agricultural Science for Senior Secondary Schools by O. A. Iwena
- Agricultural Science WAEC PQ
- Practical approach to animal production and health by Akinlade J. A. et al.
- General outlook to livestock production by Akinlade J. A. et al.
- Essential biology for Senior Secondary Schools by M. C. Michael
- Wikipedia
WEEK EIGHT
ENVIRONMENTAL PHYSIOLOGY
CONTENT
- Definition
- Effect of changes in climate on growth, milk production and egg production
Environmental physiology refers to the effects of the environment on the growth and performance of farm animals. It is the study of the environment in relation to the response of farm animals. The effects could be high or low in nature. Moderation is the target for optimum growth and performance.
CLIMATE
Climate refers to the atmospheric condition of a place over a period of time. It is marked by rainfall, wind, temperature, humidity, sunlight etc.
RAINFALL
- High rainfall increases pests like tsetse flies, and diseases
- High rainfall causes chilling of young ones
- High rainfall does favor rearing of dairy animals
- Extremes of rainfall do not favor growth of grasses for foods
CONTROL OF RAINFALL
- Shelter
- Rain break
- Drainage channels
- Building orientation
WIND
- Wind aids the spread of air-borne diseases e.g. tuberculosis; and death eventually
- Moderate wind velocity promotes good ventilation.
- Scare animals producing undesirable level of growth hormones.
CONTROL OF WIND
- Shelter
- Wind break
- Openings
- Building orientation
TEMPERATURE
- High temperature causes a reduction in food intake; low temperature encourages more feed intake
- High temperature reduce spermatogenesis and libido in males
- High temperature causes heat stress and reduced activity.
- It may result in death of animals; in adult animals e.g birds, young animal e.g chicks and production animals e.g layers
- It increase water intake in hot weather and reduces water intake in cold weather.
- It is necessary for incubation of eggs
- It lowers yield e.g. lower egg production
- It affects product storage period under high climatic condition
- High temperature affects the young ones e.g. hatching of egg is reduced.
CONTROL OF HEAT AND TEMPERATURE
- Introduce fans or air conditioners to animal house.
- Provide enough windows or opening for ventilation
- Cover windows with cloth materials to conserve heat
- Provide vents at the roof tops;
- Use poor conductors of heat for roofing/ sun reflecting sheets or paint roof with reflecting color e.g. white. Pens should also have ceiling boards under the roof
- Use room heaters or lanterns to warm building when it is cold
RELATIVE HUMIDITY
- It is very important in physiological processes e.g. incubation.
- High humidity compounds stress.
- Low humidity induces rapid water loss from animal body and thus increases their water intake
- High humidity encourages the spread of diseases
- High humidity causes feeds to go moldy
- Causes chilling of young ones
CONTROL OF HUMIDITY
- Fixing humidifiers or open trays filled with water to increase humidity
- Allowing free ventilation when the humidity is high
- Avoidance of spilling of water to reduce humidity or dampness e.g. in poultry house
LIGHT
- Controls egg laying in hens
- Duration of lightning controls time spent at feeding which regulates growth and the rate of feathering, furring.
- Direct light of high intensity causes stress to the eyes
- Bright light makes the animals active e.g. birds
- Light makes objects visible to animals’ eyes
CONTROL OF LIGHT
- In short daylight, provide extra illumination
- There should be openings to promote lighting e.g. use of wire meshing and glass as reasonable parts of building construction.
- 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 each more and still not grow well. Other instances includes
- Wind aids spread of disease
- High rainfall causes more incidence and multiplication of Tsetse fly and other pest
- High humidity favors mould growth in pens and also in feed which could cause diseases
A favorable climate cteris 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
- Installing fans and air conditioners
- Plan for good ventilation when constructing animal house
- Used building materials that are poor conductors of heat
- Painting walls of animal house white to reflect sun rays
- Construct farm houses east west direction
- Use mesh in place of brick wall at some heights
- Install humidifiers or open trays filled with water to increase or reduce humidity.
And try to control all they can to ensure their investment do not go to waste.
EFFECT OF CHANGES IN CLIMATE ON MILK PRODUCTION
Excess sunlight brings about heat stress, high humidity favors growth of pathogens, milk will spoil at a temperature higher than 37°C. All these causes reduction in milk yield
EFFECT OF CHANGES IN CLIMATE ON EGG PRODUCTION
High temperature reduces shelf life for eggs, hatchability, feed intake, and decrease in quantity of egg produced. Light length increases feeding time for birds which may not translate into extra yield.
EVALUATION
- What is environmental physiology?
- Write short notes on the effect of changes in rainfall and wind on growth in farm animals.
- State two air-borne diseases that affect farm animals.
GENERAL EVALUATION
- Write short notes on the effect of changes in the following on physiological processes in farm animals a) Temperature b)Relative Humidity c) Light
- 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
WEEKEND ASSIGNMENT
- The instrument used to measure the relative humidity is A.thermometer B.anemometer C.hygrometer D.hydrometer
- Which of the climate factors is likely to have the greatest effect on animal production in Nigeria? A. temperature B.air movement C. rainfall D.pressure
- The factors that can predispose animals to diseases include the following except A. poor housing B. malnutrition C. immunity D. physical injuries
- The effects of high environmental temperature on dairy cows include the following except A. fever B.high feed intake C.high water intake D.low milk production
- The equatorial rain forest belt is not usually used for cattle production because of the A. low relative humidity B.absence of natural grasslands C.incidence of Tsetse flies D.dense vegetation
THEORY
- Discuss brieflyA.rainfall B.light C.temperature in relation to poultry production.
- Write short note on the effect of temperature on brooding of chicks.
