Livestock Diseases, Prevention and Disease Management for SS 1

Disease Management in Livestock

Performance Objectives

By the end of the lesson, students should be able to:

1. state the meaning of disease and health;
2. explain the importance of disease management in livestock production;
3. classify diseases based on their causative agents;
4. describe disease preventive measures.

Meaning of Health

Health is the state of physical, mental, and physiological well-being of an animal, in which all its body organs and systems function normally and efficiently.

A healthy animal is productive, active, and shows no signs of physical or physiological distress. Maintaining animal health is the foundation of successful livestock farming.

The physical indicators of a healthy animal include:

1. Bright, clear, and alert eyes.
2. A smooth, clean, and shiny skin, coat, or feathers.
3. An active and alert posture with steady movement.
4. A normal appetite and regular rumination in ruminants.
5. Normal body temperature, pulse rate, and respiration rate.
6. Consistent and high levels of production, such as milk, meat, or egg yield.
7. Normal, well-formed faeces and urine.

Meaning of Disease

Disease is any deviation or departure from the normal structural or functional state of an animal’s body, which impairs its normal functions and is usually accompanied by specific signs or symptoms.

Diseases disrupt the physiological balance of the animal, leading to reduced productivity, poor growth, and in severe cases, death.

The physical indicators of a diseased animal include:

1. Dull, sunken, or watery eyes.
2. A rough, dry, or patchy coat, or ruffled feathers in poultry.
3. Loss of appetite (anorexia) and cessation of rumination.
4. Drooping head, arched back, or general weakness and lethargy.
5. Abnormal discharges from the eyes, nostrils, mouth, or vulva.
6. Sudden drop in milk, meat, or egg production.
7. Abnormal faeces (watery, bloody, or hard) and discoloured urine.
8. Rapid or laboured breathing and coughing.

Observe the image below to compare the physical characteristics of healthy and diseased livestock.

Importance of Disease Management in Livestock Production

Disease management refers to the combination of practices designed to prevent, control, and cure diseases in livestock. Effective disease management is critical for several reasons:

1. Maximises Productivity and Yield: Healthy animals grow faster, produce more milk, lay more eggs, and produce high-quality meat compared to diseased animals.
2. Reduces Mortality and Morbidity Rates: Proper management prevents the outbreak of deadly diseases, thereby reducing the death rate (mortality) and the sickness rate (morbidity) in the herd or flock.
3. Minimises Production Costs: Preventing diseases reduces the money spent on veterinary drugs, treatment, and professional services, making the farm enterprise more profitable.
4. Prevents Zoonotic Diseases: Some livestock diseases can be transmitted to humans. Managing these diseases in animals protects the health of farm workers and consumers.
5. Ensures Food Safety and Quality: Disease-free livestock produce wholesome milk, meat, and eggs that are safe for human consumption, free from harmful pathogens and drug residues.
6. Improves Animal Welfare: Preventing and treating diseases reduces pain, suffering, and discomfort in farm animals, ensuring ethical farming practices.

Classification of Diseases Based on Their Causative Agents

Livestock diseases are broadly classified into two main categories based on whether they are caused by living pathogens that can spread, or by non-living factors.

The diagram below shows the systematic classification of livestock diseases.

1. Infectious Diseases

Infectious diseases are caused by pathogenic microorganisms that invade the body of the animal. These diseases can be transmitted directly or indirectly from an infected animal to a healthy one.

Infectious diseases are further sub-classified based on the specific type of pathogen involved:

1. Viral Diseases: Caused by viruses. They are highly contagious and often have no cure once contracted, making prevention critical. Examples include Newcastle disease in poultry, Foot and Mouth disease in cattle, sheep, and goats, Gumboro (Infectious Bursal) disease in poultry, and African Swine Fever in pigs.
2. Bacterial Diseases: Caused by bacteria. These can often be treated with antibiotics if detected early. Examples include Brucellosis (contagious abortion) in cattle, Tuberculosis in cattle, Anthrax in ruminants, and Fowl Cholera in poultry.
3. Fungal Diseases: Caused by fungi. They often affect the skin, hair, or respiratory system. Examples include Ringworm (affecting the skin of cattle, goats, and pigs) and Aspergillosis (brooder pneumonia in young chicks).
4. Protozoan Diseases: Caused by single-celled microscopic organisms called protozoa. Examples include Coccidiosis in poultry and rabbits, and Trypanosomiasis (sleeping sickness) in cattle, which is transmitted by the tsetse fly.

2. Non-Infectious Diseases

Non-infectious diseases are not caused by living pathogens and cannot be transmitted from one animal to another. They are caused by environmental, nutritional, physical, or genetic factors.

The main types of non-infectious diseases include:

1. Metabolic and Nutritional Diseases: Caused by a deficiency, excess, or imbalance of specific nutrients in the animal’s diet, or by metabolic disorders. Examples include Bloat (accumulation of gas in the rumen due to feeding on lush, wet legumes), Milk Fever (hypocalcemia, caused by a sudden drop in blood calcium levels in lactating cows), Ketosis (caused by impaired carbohydrate metabolism in high-producing dairy cows), and Rickets (caused by a deficiency of calcium, phosphorus, or Vitamin D).
2. Physical Injuries and Trauma: Caused by accidents, poor housing design, fighting among animals, or rough handling. Examples include wounds, bone fractures, bruises, and lameness.
3. Toxic and Poisonous Diseases: Caused by the ingestion of toxic plants, chemical poisons (such as pesticides or herbicides), or spoiled feed containing fungal toxins (aflatoxins).

Disease Prevention Methods

Prevention is the most effective and economical way to manage livestock diseases. The primary methods used to prevent diseases on a livestock farm include:

1. Vaccination: This is the administration of a vaccine (containing weakened or killed pathogens) to stimulate the animal’s immune system to produce antibodies. This provides active immunity against specific diseases, such as Newcastle disease or Anthrax.
2. Biosecurity: These are practical measures designed to prevent the introduction of pathogens onto the farm and stop the spread of diseases within the farm. Biosecurity measures include fencing the farm, restricting visitors, installing footbaths at entrance points, and quarantining new animals for 2 to 4 weeks before introducing them to the main herd.
3. Hygiene and Sanitation: This involves regular cleaning and disinfection of animal pens, feeders, drinkers, and farm equipment. It also includes the proper disposal of manure, waste, and animal carcasses (through deep burial or burning) to eliminate breeding grounds for pathogens and pests.
4. Proper Nutrition: Feeding livestock with balanced rations containing all essential nutrients (proteins, carbohydrates, fats, minerals, vitamins, and clean water) in the correct proportions. Good nutrition strengthens the animal’s immune system, making it more resistant to infections.
5. Regular Deworming and Pest Control: Administering anthelmintics (dewormers) to control internal parasites (such as roundworms and tapeworms), and applying acaricides or insecticides to control external parasites (such as ticks, lice, and mites) which often act as disease vectors.

Observe the image below to see a practical biosecurity setup at a farm entrance.

How to Prepare and Use a Footbath (Biosecurity Demonstration)

A footbath is a simple and highly effective biosecurity tool placed at the entrance of livestock pens to disinfect the footwear of workers and visitors, preventing the transfer of pathogens into the animal housing area.

The required materials are:

1. A shallow plastic or concrete trough (about 10 to 15 cm deep).
2. Broad-spectrum chemical disinfectant.
3. Clean water.
4. A measuring cylinder or cup.
5. Stiff-bristled hand brush.
6. Rubber boots (wellington boots).

The procedure involves the following steps:

1. Place the shallow trough directly across the entrance doorway of the livestock pen so that anyone entering must step into it.
2. Measure the correct volume of clean water and pour it into the trough, filling it to a depth of about 5 to 8 cm.
3. Measure the recommended quantity of the chemical disinfectant according to the manufacturer’s instructions.
4. Pour the disinfectant into the water and stir gently using a clean stick to ensure a uniform solution.
5. Before stepping into the footbath, use the stiff-bristled brush to scrape off any organic matter, mud, or manure from the soles and sides of the rubber boots.
6. Step into the footbath with both feet, ensuring that the disinfectant solution completely covers the soles and lower parts of the boots.
7. Allow the boots to remain submerged in the solution for at least 30 seconds to allow the disinfectant to kill any pathogens.
8. Step out of the footbath directly onto the clean concrete floor of the livestock pen.
9. Empty, clean, and refill the footbath with fresh disinfectant solution daily, or whenever it becomes heavily contaminated with mud or organic debris.

How to Clean and Disinfect a Poultry Pen (Hygiene and Sanitation Demonstration)

Regular cleaning and disinfection of livestock pens break the life cycle of pathogens and parasites, ensuring a safe environment for the animals.

The required materials are:

1. Brooms and scrapers.
2. Shovels and wheelbarrow.
3. Water hose or buckets of clean water.
4. Liquid detergent or soap.
5. Disinfectant solution.
6. Knapsack sprayer or watering can.
7. Personal protective equipment (nose mask, hand gloves, and rubber boots).

The procedure involves the following steps:

1. Remove all livestock from the pen and transfer them to a temporary holding area.
2. Remove all portable equipment, such as feeders, drinkers, and nests, from the pen.
3. Use shovels to scrape and remove all old litter, manure, and dust from the floor and walls. Load the waste into a wheelbarrow and transport it far away from the pen.
4. Use a broom to sweep down cobwebs, dust, and loose dirt from the ceiling, roof trusses, and walls.
5. Wet the floor and walls with clean water, apply the detergent, and scrub thoroughly using stiff brushes to remove stubborn organic stains and grease.
6. Rinse the entire pen thoroughly with clean water to remove all soap suds and loosened dirt. Allow the pen to drain and dry.
7. Prepare the disinfectant solution in a knapsack sprayer or watering can according to the manufacturer’s instructions.
8. Spray or apply the disinfectant solution systematically, starting from the ceiling and roof trusses, moving down the walls, and finishing with the floor. Ensure all cracks and crevices are thoroughly soaked.
9. Wash, scrub, and disinfect the feeders and drinkers separately before returning them to the pen.
10. Allow the pen to dry completely and air out for at least 24 to 48 hours before introducing fresh litter material and returning the animals.

Summary of Common Livestock Diseases

The table below provides a summary of common livestock diseases, their causative agents, and key prevention methods.