Supplementary Readings - 1 | Animal Husbandry & Veterinary Science Optional for UPSC PDF Download

Importance of Water for Livestock

• Essential for Animals: Water is crucial for domestic livestock, serving as a necessity for drinking and maintaining cleanliness in their living spaces.
• Key for Dairy and Meat Production: Large quantities of good-quality water are needed in dairies, creameries, and abattoirs for the production of dairy products and meat.

Quality of Water

• Natural Impurities: Water from natural sources contains impurities like dissolved gases, minerals, and substances from animals, along with suspended organic or inorganic particles.
• Source Dependency: The quality of water depends on its source, exposure to pollution, and the methods used for storage and purification.

Understanding "Pure Water"

• Literal Sense: Pure water, in its truest form, is not found in nature. The term "pure water" for livestock means water that is free from turbidity, color, taste, and smell.
• Wholesome Water: Wholesome water is free from harmful elements like pathogenic organisms and poisonous materials such as lead or zinc.

Categories of Natural Water

• Atmospheric Water: Includes rain and snowwater.
• Surface Water: Water that has touched the ground, like rivers and streams.
• Stored Water: Water stored in reservoirs or tanks.
• Groundwater: Water obtained from underground sources.

Key Points for Layman's Understanding

• Animals need water not only for drinking but also for maintaining a clean environment.
• Dairies and meat processing require a significant amount of good-quality water.
• Natural water has impurities that depend on the source and how it's stored.
• "Pure water" for livestock means water without color, smell, taste, and turbidity.
• Wholesome water is safe for animals and lacks harmful elements.
• Different types of natural water include rainwater, surface water, stored water, and groundwater.

Water Impurities

• Types of Impurities:
  • Inorganic impurities include calcium, magnesium, sodium salts, iron, and fluorine.
  • Organic impurities can be chemical or biological, arising from soil breakdown or decomposed plant and animal life.
• Biological Inclusions:
  • Biological impurities encompass various plant and animal life, such as algae, fungi, bacteria, protozoa, insects, and fishes.

Water Hardness

• Definition of Hardness:
  • "Hard" water feels harsh when soap is used, forming less lather.
  • "Soft" water easily forms a soapy lather and feels smooth.
• Causes of Hardness:
  • Calcium and magnesium salts in water react with soap, forming insoluble curd or scum.
  • Bicarbonates, sulphates, and chlorides of calcium and magnesium contribute to water hardness.
• Temporary and Permanent Hardness:
  • Temporary hardness, due to bicarbonates, can be removed by boiling.
  • Permanent hardness, from sulphates and chlorides, requires chemical treatment.
• Water Hardness Grading:
  • Ranked from softest to hardest: rainwater, upland surface water, water from cultivated land, river water, spring water, deep-well water, and shallow-well water (may still contain soft water).
• Measuring Hardness:
  • Hardness is measured by determining the amount of soap solution needed for lather.
  • Expressed as parts of calcium carbonate per 100,000 ml of water or occasionally in grains per gallon.
• Boiling and Chemical Treatment:
  • Boiling removes temporary hardness, while chemical treatment is needed for permanent hardness.
  • Relative hardness helps in understanding the water's quality.
• Convenience in Measurement:
  • Expressing hardness in parts per million is a more practical and modern approach.

Importance of Hard and Soft Waters

• Effects on Health:
  • Hard waters have been linked to health issues like goitre, kidney stones, indigestion in humans, and dry coat and gastric problems in horses.
  • Soft waters are said to slow down teeth calcification in children, potentially leading to dental problems later in life.
• Soap Wastage and Cleaning:
  • Hard water leads to excessive soap wastage compared to moderately soft water when used for washing.
  • Waste pipes in kitchens and lavatories can get coated with insoluble salts, causing foul smells, but synthetic detergents are unaffected by water hardness.
• Household Appliances:
  • The build-up of calcium and magnesium carbonates in kettles and boilers causes "fur" deposits.
  • "Boiler scale," due to sulphate deposition, can affect appliances. Soft water is preferred for making solutions of disinfectants and other purposes.
• Practical Considerations:
  • Synthetic detergents work well in hard water, preventing the need for excess soap and minimizing pipe blockages.
  • Soft water is recommended for specific applications like disinfectant solutions and sheep-dip.

Treating Hard Water

• Why Treat Hard Water:
  • Hard water is not suitable for household and industrial use.
  • Measures are taken to remove hardness, especially when dealing with large quantities.
• Removing Temporary Hardness:
  • Boiling is effective for small amounts of water.
  • For larger quantities, chemical methods are used.
• Lime-Soda Softening:
  • Chemical processes aim to precipitate calcium and magnesium salts.
  • Slaked lime reacts with calcium bicarbonates and magnesium salts to form insoluble calcium carbonate and magnesium hydroxide.
  • This process removes temporary hardness due to calcium and any hardness due to magnesium.
• Handling Permanent Hardness:
  • Some calcium salts cause permanent hardness and do not react with lime.
  • Sodium carbonate, commercially known as "soda-ash," is added in the Lime-Soda Process to precipitate these salts as insoluble calcium carbonate.
  • This process eliminates both temporary and permanent hardness, leaving a small amount of sodium sulfate in the water.
• Result of Lime-Soda Process:
  • Water treated using Lime-Soda Process becomes free of hardness.
  • Ferruginous waters with iron content can also be treated using this process.
• Base-Exchange Process:
  • Not suitable for waters containing iron.
  • The combined Lime-Soda Process effectively softens water, making it suitable for various uses.

Water Softening by Base-Exchange

• Natural Process:
  • Calcium and magnesium salts in water can naturally be converted to sodium salts through a base-exchange reaction.
  • This process is utilized for large-scale softening of water for industrial and domestic use.
• Ion Exchange Property:
  • Certain minerals, like clay and aluminosilicate minerals, and synthetic materials known as "Zeolites," possess ion exchange properties.
  • "Permutit" is a commonly used Zeolite for water softening.
• Chemical Reactions:
  • During water softening, calcium bicarbonate in hard water reacts with Zeolite, replacing calcium with sodium.
  • This process effectively removes both temporary and permanent hardness.
• Regeneration Process:
  • Over time, all the sodium in the Zeolite gets replaced by calcium, leading to the need for regeneration.
  • Regeneration involves treating the exhausted Zeolite with a strong solution of brine (sodium chloride), converting it back to sodium Zeolite.
• Continuous Operation:
  • The process can be repeated intermittently for an extended period without significant loss of efficiency (about 1% loss after 200 cycles).
  • Zeolites like "permutit" can replace all calcium and magnesium in hard water with sodium in a single operation.
• Alkalinity Concerns:
  • Water softened by the base-exchange process may have increased alkalinity due to the replacement of calcium and magnesium salts with sodium.
  • However, these softened waters are confirmed to be wholesome and may even be better than the original hard waters.
• Alternative Materials:
  • Acid-treated coal and bakelite are now used for water treatment.
  • Besides base-exchange, these materials can undergo acid-exchange, enhancing water purification capabilities.
• Applications in Laboratories:
  • Small-scale plants use these materials to produce purified water from tap water for laboratory use.
  • The process involves replacing dissolved bases with hydrogen, resulting in purified water.

Water Treatment and Purification

• Acid-Exchange Process:
  • Acid water undergoes acid-exchange in the second unit, replacing all acids with carbonic acid.
  • Treated water contains only carbonic acid, which can be removed if necessary through aeration.
• Regeneration Process:
  • Zeolites in the units are regenerated using sulphuric acid in the first unit and sodium carbonate in the second.
• Corrosive Action on Metals:
  • Pure water has little corrosive action on metals.
  • Natural waters, due to dissolved substances, can corrode metals, particularly lead and zinc.
• Plumbo-Solvent Action:
  • Some waters, especially those passing through lead pipes, can exert a corrosive action known as plumbo-solvent action.
  • Animals drinking such water may ingest minute quantities of lead, posing a risk of toxicity.
• Water Purification Methods:
  • Methods depend on the scale of water treatment: large-scale for public supply or smaller quantities for domestic and farm use.
• Large-Scale Purification Processes:
  • Storage serves as a water purifier by allowing sedimentation of suspended matter and exposure to sunlight.
  • Filtration, with or without coagulants, involves percolating water through slow or rapid sand filters.
  • Chemical sterilization, commonly done through chlorination, aims to destroy non-sporulating pathogenic organisms.
• Examination of Water Supplies:
  • For domestic or livestock use, a thorough examination is crucial.
  • Topographical examination considers the source of supply and potential contamination.
  • Physical and chemical examinations, bacteriological examination, and microscopic examination are performed.
• Concerns for Animal Water Supplies:
  • Topographical survey is vital for animal water supplies.
  • Farms and pastures relying on surface waters need examination for possible pollution sources like animal waste.
  • Attention to well construction is essential to prevent surface and drainage water entry.
• Toxic Impurities:
  • Chemical and bacteriological examinations are essential, especially when toxic impurities are suspected.
  • Specialist laboratories conduct these examinations, but veterinarians should know how to collect water samples.

Understanding Bacteriological Examination Results for Water Quality

• Interpreting Results:
  • Interpreting bacteriological examination results, especially for coliform bacilli, requires careful consideration of various factors and experience in the field.
  • Conclusions drawn from laboratory data are influenced by individual experience and may vary.
• Key Factors in Interpretation:
  • Bacteriological condition of water should be considered in relation to factors like season, source nature, topography, and frequency of examination.
• Hygienic Classification Based on:
  • Bact. coli: Indicates recent excretal pollution. Its presence in water in significant numbers is a serious concern and should not be ignored.
  • LA.C. Group: Presence without faecal coli may be due to soil contamination, distant excretal material, contaminated water from a person with LA.C., or inadequate chlorine treatment.
• Proportions of Faecal Coli:
  • High proportions suggest heavy or recent excretal pollution.
  • Majority of coliform organisms belonging to LA.C. or irregular types indicate slight, infrequent, or remote pollution, or simple soil contamination.
• Significance of I.A.C. Group:
  • Presence of I.A.C. group should not be neglected, even if no faecal coli is found. It may indicate minor pollution that could escalate.
  • Appearance in water, especially where normally absent, warns of potential pollution and enables preventive measures.
• General Guidelines:
  • Faecal Coli: Denotes recent and possibly dangerous contamination, requiring urgent attention.
  • LA.C.: Suggests less recent contamination, not immediately dangerous but calls for steps to ensure greater purity.
  • I.A.C.: In treated water, indicates inadequate treatment or the entry of undesirable material post-treatment.

Water Supplies for Animals

• Hygienic Requirements:
  • Standards for animal water supply differ from those for humans, but on dairy farms, where water serves both animals and cleaning, high hygienic standards are essential.
  • Clean drinking water for animals is crucial, free from pathogenic microorganisms, parasites, mineral poisons, and objectionable taste or smell.
• Contamination Warning Signs:
  • Water with turbidity and suspended particles signals potential danger, indicating exposure to pollution, animal waste, or organic matter.
• Water Requirements for Dairy Cows:
  • Dairy cows and buffaloes need about 27 to 28 liters of water per day for maintenance, plus 1 liter for every 0.45 kg of milk produced.
  • Additional 45 to 70 liters are required for cleaning cowsheds, utensils, etc.
  • A minimum of 110 liters per day is necessary, but providing 130 to 180 liters is advisable.
  • Water should be given at least three times a day in summer and twice a day in winter.
• Water Requirements for Horses:
  • Horses, under average stable conditions and moderate work, consume around 36 liters of water daily.
  • If fed on green grass, the consumption is lower.
  • An additional 36 liters are needed for washing and cleaning the stable.
  • Hot weather and hard work may double the drinking water quantity.

Water Needs for Various Animals

• Camels:
  • Daily water requirement: 18 to 36 liters.
  • After a long period without water, they may drink up to 90 liters.
  • Should be given water twice a day in summer, once a day in winter.
• Sheep and Goats:
  • Prefer green grasses, requiring less drinking water.
  • Milking sheep and goats need more water.
  • Recommended to have water available twice a day, or preferably always accessible.
  • Average daily allowance: 18 liters per animal.
• Pigs:
  • Daily water requirement: 22 to 25 liters, varies with age, weight, feed, and season.
  • Additional water (25-28 liters) needed for washing, cleaning, etc.
  • Average total requirement: about 40 liters.
• Poultry:
  • Continuous water supply essential.
  • Birds have limited water retention capacity.
  • Under intensive poultry rearing, 20 to 30 liters per day needed for 100 hens.
  • Automatic waterers used to ensure a constant supply without unnecessary spilling.
• Dogs and Cats:
  • Daily requirement: 14 liters for drinking and washing.
  • Water should be provided throughout the day.
  • It is advisable to warm water in cold weather.
  • Large drinks before fast or strenuous work should be avoided.

Concerns and Diseases Related to Water Supply

• Johne's Disease in Cattle:
  • Believed to spread through contaminated water and ingesta with infected feces.
  • Johne's bacillus can survive outside the animal body.
  • Prevent cattle from entering and polluting water sources.
• Other Water-Borne Infections:
  • Diseases like tuberculosis, bovine contagious abortion, anthrax, blackquarter, swine erysipelas, and parasitic infestations can be water-borne.
  • Proper prevention measures needed to avoid contamination.

Air Quality Basics

Understanding Air Composition

• Essential to grasp:
  • Types of impurities in the air.
  • How these impurities accumulate.
  • Tolerance levels for humans and animals.
  • Methods to purify polluted air.
• Impact of Crowded Spaces:
  • Crowded areas alter air composition.
  • Overcrowded spaces can reduce vitality and productivity.
  • Ventilation is crucial to remove polluted air and maintain a healthy atmosphere.

Composition of Atmospheric Air

• Air is a mixture of gases:
  • Oxygen: 20.94%.
  • Carbon dioxide: 0.028 to 0.04%.
  • Nitrogen: 71.04%.
  • Traces of argon, helium, krypton, neon, etc.
  • Also contains traces of ammonia, ozone, nitric acid, free hydrogen, and methane.
• Approximately 1.4% moisture is present as gas, not droplets.

Atmospheric Humidity

• Humidity refers to the amount of water vapor in the air.
• Vapor pressure measures the amount, increasing with temperature.
• Absolute Humidity: Actual weight of water in a given volume.
• Relative Humidity: Ratio of actual water vapor to saturated vapor at a given temperature.

Pollution of Atmospheric Air

• Air near humans and animals changes due to their activities.
• Normal processes alter oxygen and increase carbon dioxide and methane.
• Combustion, decomposition, industrial processes contribute to air pollution.
• Factories discharge gases and substances, regulated by laws to control harmful emissions.

Air Quality Standards and Animal Housing

• Hydrochloric Acid Gas Emissions:
  • Limit: Not more than one-fifth of a grain per cubic foot of air.
  • Restriction on the discharge of smoke or chimney gases into the atmosphere.
• Sulphur and Nitrogen Acid Gas Limits:
  • Sulphuric anhydride discharge limit: Equivalent of four grains per cubic foot of air.
  • Control on acid gases from sulphur and nitrogen.
• Free Ammonia Control:
  • Presence of free ammonia from urea decomposition in poorly ventilated animal houses.
  • Good hygiene practices should prevent appreciable amounts of free ammonia.
• Organic and Particulate Matter:
  • Common presence in animal habitations.
  • Form: Droplets from pulmonary exhalations, dust, pollen, and particulate matter.
  • Includes suspended impurities from cuticular debris, desiccated feces, and feeding materials.
  • Presence of molds and bacteria, with potential hygiene significance.
• Respiratory Changes:
  • Respiration involves gaseous exchange, leading to chemical and physical alterations in expired air.
  • Changes include reduced oxygen (O₂) and increased carbon dioxide (CO₂) compared to inspired air.
  • Average composition of expired air in humans: O₂ 16%, CO₂ 4.24%, N₂ remains similar.
  • Herbivorous animals' expired air contains methane from carbohydrate fermentation in the digestive system.
  • Chemical composition variations result from differences in food types and respiration patterns.
• Carbon Dioxide (CO₂) Excretion:
  • Average CO₂ excretion during rest for a human is 0.6 cubic foot per hour.
  • Increases during active work and food digestion.
  • CO₂ excretion rates vary in different animals based on weight, surface area, and activity.
  • Larger animals produce proportionately less CO₂ compared to smaller ones.
• Hourly CO₂ Excretion Estimates:
  • Cows in Milk: 5.8 cubic feet
  • Horses: 3.9 cubic feet
  • Swine: 1.3 cubic feet
  • Sheep: 0.55 cubic feet

Understanding Air Changes and Ventilation in Animal Environments

Animal CO₂ Excretion Rates

• Dog (60 lbs.): Approx. 0.3 cubic feet of CO2 per hour.
• Cows in Milk and Fattening Cattle: 6 cubic feet per hour.
• Heavy Draught Horses (approximately 1600 lbs.): 6 cubic feet per hour.

Physical Changes in Expired Air

• Warming to body temperature.
• Saturated with water vapor in the lungs, visible in cold weather as a condensation cloud.
• Expanded volume, making it less dense than normal atmospheric air.

Effects of Poor Ventilation

• Immediate ill-effects include depression, headache, drowsiness, and reduced efficiency in physical and mental work.
• Prolonged exposure to poorly ventilated spaces lowers natural resistance to diseases in both humans and animals.
• Some evidence suggests improved yields of milk or eggs when animals experience better air conditions.

Importance of Air Composition Changes

• Understanding the impact of air composition changes is crucial for ventilation in animal buildings.
• Previously, discomfort was attributed to decreased O₂ and increased CO₂, but this idea was refuted by research.
• Sir Lenard Hill's experiments showed that discomfort results from heat stagnation, excessive moisture, and lack of air movement.

Understanding Oxygen and Carbon Dioxide Levels in Indoor Air

Oxygen Decrease

• Research by Hill showed that humans can tolerate O₂ levels as low as 15%, where regular combustion doesn't occur.
• In crowded rooms, O₂ rarely drops below 20%, and harmful effects are usually felt below 12%.
• Consciousness is not lost until O₂ falls below 7%.

Carbon Dioxide Increase

• Indoor air always contains more CO₂ than outside air, but it seldom reaches levels causing toxicity.
• In places like theaters, CO₂ rarely exceeds 0.5%, and commercial cowsheds typically have 0.2-0.3%.
• Experimental evidence suggests that CO₂ can reach 2-3% without noticeable effects, even up to 3.5% in submarines.
• Past beliefs that CO₂ is harmful in slightly elevated concentrations are now challenged by scientific evidence.

Air Pollution Indicators

• Increase in CO₂ is considered an indirect indicator of air pollution resulting from animal metabolism.
• However, relying solely on CO₂ levels for assessing air quality is considered incomplete and unscientific.
• Other factors like temperature, humidity, and organic matter in the air should also be considered.

Effects of Temperature and Humidity on Animals in Confined Spaces

Increased Temperature and Moisture

• Animals in poorly ventilated buildings experience higher air temperature and humidity.
• These changes result from the heat and water released by animals into the air.
• Elevated temperature and humidity create an environment where heat loss from the body is challenging.

Impact on Heat Loss

• High environmental temperature reduces heat loss by radiation.
• Increased air humidity limits evaporation, a crucial process for cooling.
• Inadequate ventilation compounds the issue by preventing air movement necessary for effective heat dissipation.

Heat Stagnation

• The combined effect of high temperature, humidity, and poor ventilation leads to heat stagnation in the animals' bodies.
• Heat stagnation is identified as the primary cause of discomfort and related symptoms in animals, as observed in humans in poorly ventilated spaces.

Importance of Air Movement

• Adequate air movement is crucial to prevent the accumulation of warm, moist air around animals.
• Without proper ventilation, the enveloping air limits the body's ability to cool through natural processes like radiation and evaporation.

Sources of Air Vitation

• Besides animal-related factors, air quality is affected by decomposing excreta and bedding.
• Water on floors from cleaning operations and moisture on walls contribute to increased internal humidity.