anfs 340 exam 1
Ventilation
Critical for cow productivity Determined by amount of air changes needed for moisture removal Free-stall barns should be built with an open ridge, high sidewalls, adequate roof slope •Two or four row barns have better ventilation •East-west facing barns reduces radiant energy loads •Air moves up and out of ridge vent because of heat generated by cows, pulling fresh air in through open sidewalls -Only need 2-3 degree difference in temperature to make it work -Dependent on animal size, density, outside temperature
Maintaining Body Temperature
Vasoconstriction Vasodilation Panting and sweating Fluffing feathers and huddling Extending limbs/wings
Mechanical System
Ventilation Measuring/monitoring -Temperature -Relative humidity -Static pressure Controlling -Heaters/cooling pads/foggers/sprinklers -Fans ON/OFF -Inlet/vent box size
Ventilation Control
Ventilation system including fans and inlets Controlled by controller Fans -ON:OFF -Speed is normally not controlled Inlets -Opening area is controlled through static pressure Use negative pressure system Slight vacuum: ΔP from 0.05 to 0.1 inch water column (w.c)1"w.c = 248.8 paΔ P: static pressure Multiple fans -All fans operate against same ΔP -Airflow are additive from each fan as the operating ΔP -Propeller fans with 3 to 6 blade propeller
Ventilation of shelter and enclosure
manage thermal and air environment -Cooling, heating, air hygiene Natural by using openings Mechanical with fans Mixed ventilation with combination of natural and mechanical ventilations
Sensible heat loss
occurs when body temperature rises and sweating increases water vaporization Conductive, convective, and radiative exchanges require a temperature gradient (ΔT) Less effective as air temperature approaches skin temperature
Responses to thermal environment
Nutritional responses -Feed intake Physiological responses -Respiration rate, body temperature, heart rate Behavioral responses -Huddling -Fluffing feathers, extending wings -Panting, sweating
Laying hen housing
Pullet barn: day old to 16 wks of age -Environmentally controlled housing with heating Layer barn: 16 wks to 65 or 80 wks of age
Tunnel Ventilation
Purpose: -Flow high-velocity air onto animals -Need wind chill effect Equipment used: -Tunnel inlets -Tunnel fans used -May add evaporative cooling Sidewall inlets and fans fully closed and not used
Minimum Ventilation
Purpose: -Ventilate for good air quality -Remove moisture build-up -Conserve house heat Conditions: -Cold weather -Young animals -Outside air below inside optimum -Providing supplemental heat Fans and inlets used: -Sidewall fans -Sidewall inlets Tunnel inlets and fans fully closed and not used.
Transitional Ventilation
Purpose: -Ventilate to control inside temperature -Blend outside cool air with in-house air - prevent cool air directly contacting animals -Move more air, but no wind chill Fans and inlets used: -Sidewall inlets -Up to half tunnel fans used Tunnel inlets and sidewall fans fully closed and not used
Cross ventilated houses
Use ceiling or eave inlets Fans are on side-walls Commonly used -Locations with long cold season -Small operations -Younger animals High air speed is not required -Air speed at animal level varies ( 0 to 300 FPM) Fans distribution and installation are easier.
Naturally-ventilated buildings are most satisfactory for adult animals.
Usually, younger animals require higher temperatures in winter and more precise environmental control than can be supplied by a natural ventilation system.
Microenvironment
the physical environment immediately surrounding it—the primary enclosure with its own temperature, humidity, and gaseous and particulate composition of the air. Such as pen, cage.
thermoneutral zone (TNZ)
the range of ambient air temperatures where an endotherm can maintain a constant core body temperature with a minimal metabolic heat production. Dynamic and affected by Acclimation, Air movement, Relative humidity, Age, Weight, Exposure to direct sunlight
Dairy housing system around production cycle
'Dry' period (2m) Calving- birth of the calf Lactation- production of milk (2-4 m) Insemination- where a cow becomes pregnant Pregnancy (Gestation) (9m)
Different housing systems
-Companion, farm, laboratory animals -To meet the needs of the animals -Maintenance of body temperature, normal movement, reproduction -Social interaction -Remain clean -Adequate ventilation -Access to food and water -Safety and security -Naturalistic environment -Sheltered environment -Enclosures
Animal Environment, Housing, and Management
-Essential requirement -Animal well-being -Quality of research data and teaching or testing programs -Health and safety of personnel -A good management program -Provides the environment, housing, and care that permit animals to grow, mature, reproduce, and maintain good health -Provides for their well-being -Minimizes variations that can affect research results
Static Pressure Control
0.04 to 0.1 inch w.c(10 to 25 pa) -Inlet air: 4 to 6.5 m/s (800 to 1200 fpm) Provide desired and effective air mixing -Maximize the tempering of the incoming air -Keep the air away from animal Overcome wind effects on static pressure Maximize fan performance
Static Pressure Control
0.04 to 0.1 inch w.c(10 to 25 pa) -v: 4 to 6.5 m/s (800 to 1200 fpm) Provide desired and effective air mixing -Maximize the tempering of the incoming air -Keep the air away from animal Overcome wind effects on static pressure Maximize fan performance
Basic animal needs and requirements (5 freedoms)
1. Freedom from hunger and thirst -Readily accessible fresh water and nutritionally adequate food as required, 2.Freedom from pain, injury and disease 3.Freedom from fear and distress 4.Freedom of movement to express normal behavior -Social contact with herd mates 5.Freedom from discomfort -Providing an appropriate environment including shelter and a comfortable resting area -Sufficient light -Complexity and change in their environment to avoid boredom
Factors that Affect Relative Humidity
1.Amount of water: If you increase the amount of water in the air (by adding it due to evaporation), Relative humidity will go up. 2. temperature: Since warm air can hold more water than cold air, if you lower the temperature the Relative Humidity will go up, even if you don't add more water.
Maternity stalls
120 -200 sqft per stall One stall per 20 milk cows in herd
Humidity
A measure of the amount of water in the air. Water is added to the air by the process of EVAPORATION.
Cutaneous Evaporative Heat Loss
Active evaporation from the skin surface with sweat glands: sweating -sweating rate (SR): horse>cow and cattle > sheep -Poultry or pig does not have sweat glands -Affected by environmental factors --Relative humidity: sweating rate decreases with increasing RH --30%-90% of RH, 500-60 g water/m2h of SR --Air velocity: high velocity high sweating rate -Affected by changes in hair coats Passive (diffusion) evaporation from skin -Very effective for pigeons
Lighting environment
Affect physiology, morphology, and behavior -Species, stain, age Photo stressors -Photoperiod -Intensity -Quality of light
How can heat stress be managed? How to cool animals?
Air exchange Shade Water Air velocity
Wind-Chill
Air movement increases convection heat loss Wind-chill temperature is based on a combination of air temperature and wind speed. As air temperature decreases and wind speed increases, the air feels colder because the temperature difference between skin and air is maximized as any warmed air is quickly replaced by cold air. That larger temperature difference increases heat flow, and sense of coldness. Assume one animal is exposed to a still air environment at a temperature, Twind-chill, and another animal is exposed to a windy environment at a different temperature, Tair, and they lose same amount of heat. hstill(Tsurface, still - Twind-chill) = hwind-chill(Tsurface, wind-Tair) Wind-chill temperature drop (ΔT)increases with lower air temperature
Ventilation Fundamentals
Air moves due to pressure differences -From high to low pressure System designed to supply fresh air -Supplying oxygen -Removing undesirable gases -Control Moisture -Control Temperature
Wien's Displacement Law
All objects above absolute zero emit radiant energy and the rate of emission increases and the peak wavelength decreases as the temperature of object increases λpeak=bλ/T Wien constant: bλ=2.898×10^-3m.K
Dry bulb temperature (DB)
Ambient temperature = temperature on normal house thermometer
Vasodilation
As air temperature ↑, surface blood vessels dilate to ↑blood flow, ↑heat loss
Vasoconstriction
As air temperature ↓surface blood vessels contract to reduce blood flow & therefore heat loss
Lower critical temperature
At this ambient temperature the animal minimizes sensible heat loss by fluffing its fur (pilomotion) or feathers (ptilomotion), assumes a posture to minimize its surface area, and protects its poorly insulated extremities by vasoconstriction of its cutaneous blood vessels. When ambient temperature falls below the lower critical temperature, the animal recruits just enough metabolic heat production through shivering, non-shivering thermogenesis, or by muscular activity(e.g., exercise) to offset extra heat lost to the environment.
Ventilation (air movement) pattern
Avoid cold air draft for cold weather -Proper inlets placement -Stop infiltration (leakage and gap from unwanted places) Promote wind-chill for hot weather -High air speed •Fans •Tunnel ventilation
Factors of cold resistance
Bodyweight (BW) -The higher BW, the more resistant to cold -Lower surface area to body mass ratio -less heat loss -Lower BW, lower pelage population density, shorter hair fiber length, less stored energy Age -Cold resistance is improved with age
Cow production cycle
Born •Heifer calves retained for herd (1-3 d) Weaned •6-8 weeks Bred •15 months First Calf •24 months Breeding •60-120 days post-calving Milking •10-14 months Dries off •Dry for 60 days Calving •280 days after breeding
Housing for replacement heifers
Can be open shed Bedded to keep animals dry Protect from drafts, rain, snow, and winds Artificial shade might be needed in warm climates
Heaters - Radiant tube
Capacity: 100,000 to 150,000 BTU (29 to 43 kWhr) Need ventilation to bring fresh air and remove toxic gases Animals -Pullets -Broilers -Turkeys -Nursing pig
Heaters - forced air
Capacity: 40,000 to 250,000 BTU (12 to 73 kWhr) Environmentally controlled house Need ventilation to bring fresh air and remove toxic gases Animals -Poultry breeders -Pullets -Broilers -Turkeys -Swine
Shade lowers the solar heat load from direct and, sometimes, indirect radiation.
Cattle, cow, sheep Organic and small operations Seasonal Cost of materials
Fluid mechanics Basics of Air Inlets
Coanda effect: air jets attach to a solid boundary Air velocity decay and profiles of inlets
Natural Ventilation
Cold weather -Most openings are closed to minimize ventilation and maintain the temperature as high as possible. -Air quality and moisture are neglected. -Lack of control •Openings are manual control or adjusted. Hot weather -Most openings are opened to maximize ventilation and maintain the temperature as low as possible. -Ventilation is dominated by wind. -Lack of control •Especially for calm days! •Mechanical mixing fans are needed to generate high air speed. Moderate weather -Between cold and hot weather management -Openings are manually controlled depending on temperature. -Ventilation is dominated by wind. -Lack of control
Gas heater
Combustion/burning=heat Heat value -Propane: 2,500 BTU/ft3 -Natural gas: 1,000 BTU/ft3 CxHy+ O2=X CO2+ Y/2H2O + heat
Condensation
Condensation is the process by which a gas, such as water vapor, becomes a liquid. Condensation will occur when the air is SATURATED, or has a relative humidity of 100%.The air can't hold any more water vapor, so the water condensed out of the air. This commonly happens when moist air is cooled, or comes in contact with a cool surface.
Three modes of heat transfer processes
Conduction, convection, and radiation
Nursery barn
Contain several rooms with each room designed to accommodate the number of pigs from an individual farrowing room Small pens designed to handle 6 to 8 pigs are very common although some pens may be large enough to handle 16 to 25 pigs Supplemental heat is provided via heat lamps, radiant heaters or perhaps heat in the floor
How to control high humidity in animal houses?
Controller turns fans on for More ventilation! Under cool and cold weather outside air is usually cooler and dryer and carrying much less humidity. -When cool air is heated by heat from animal and heater, RH level drops. -Minimum ventilation is needed to keep RH low!!! Under warm and hot weather humidity control mainly relies on temperature control -Cool air is provided to lower temperature by higher ventilation -The adequate air ventilation will keep the RH low.
Common gas heater recommendation
Depends on housing structure and animal species Need enough ventilation to remove moisture and CO2 Recommendation: 30 to 60 BTU per ft2 -Radiant/infrared heaters = 5-6 in brooder section of 500 ft house -Pan brooders = 30,000-40,000 BTU; 20-30 per 500 ft house* -Forced hot air, hanging gas heaters = 150,000-170,000 BTU; 5 per 500 ft house, with 3 in brooder section
Animal housing
Designed to meet the animal needs -Thermal comfort -Adequate space -Social group -Manure/waste handling -Adequate ventilation -Adequate food and water access -Safety Primary enclosure (pen, stall, stable, cage, crate, etc.) Secondary enclosure (barn, shed, house, etc.)
Natural ventilation advantages
Energy: NV does not require energy to operate fans or a furnace, which means fuel conservation and cost savings. Animal safety: Because NV systems do not require fans, confinement animals would not be affected by electrical power failures.
Natural System
Environment can be monitored Large variations Controlling requires experiences and is more difficult Labor intensive -Young animals in winter -large animals in summer
Temperature
Expansion type thermometer Electronic sensors -Contact type sensors --Thermocouples --Thermistors -Non-contact type sensors: infer temperature by measuring the thermal radiations emitted by an object. --IR thermometer
Ventilation Fans
Fan flowrate deceases with increasing ΔP Vmax-Vmin Fan curve: flowrate vs. ΔP
Static Pressure
Fans and inlets create static pressure Directly correlated to inlet air velocity ↑ static pressure = ↑ air velocity ↓ static pressure = ↓ air velocity Inlets used to control static pressure & air velocity Controller monitors static pressure & uses vent controller to control static pressure by varying the size of vent opening
Positive pressure
Fans pushing air into house Pushing air out of house through vents
Negative pressure
Fans pushing air out of house Creates lower pressure in house Atmospheric outside pressure greater = pressure differential (∆ P) Greater outside pressure forces air into house thru side wall vents (inlets)
Feather fluffing and huddling
Fluffing -Increases feather insulation -Reduce heat loss Huddling -Reduce heat loss with smaller surface area
Forced flow
Fluid is forced to flow over a surface or in a pipe by external means such as a fan or a pump
Natural flow
Fluid motion is due to natural means such as the buoyancy effect, which manifests itself as the rise of warmer (and thus lighter) fluid and the fall of cooler (and thus denser) fluid.
Fourier's Law - Thermal Conductivity
For a plane wall having a temperature distribution T1to T2, and a cross section area A (perpendicular to the x- direction),the heat transfer rate (qx) by conduction through the wall in the x- direction is given by: qx=-kA(T1-T2)/L k is the thermal conductivity, W/(m oK). It is a transport property of a material. Heat flux, qx" isqx in the x-direction per unit area perpendicular to the direction of qx qx"=-k(T1-T2)/L
Factors to be considered
For adequate and appropriate physical and social environment, housing, space, and management -The species, strain, and breed of the animal and individual characteristics, such as sex, age, size, behavior. -The ability of the animals to form social groups, whether the animals are maintained singly or in groups. -The design and construction of housing. -The availability or suitability of enrichments. -The project goals and experimental design. -The intensity of animal manipulation and invasiveness. -The presence of hazardous or disease-causing materials. -The duration of the holding period.
Environmental condition: Temperature Relative humidity Ammonia Particulates Light
For temp-particulates: Micro: higher, macro: lower light: Micro: lower, Macro: higher
Temperature-Humidity Index (human)
Good for warm and hot seasons Limitation: no efforts on airspeed and radiation heat loads
Loosing housing
Group housing (Straw yard) system -Cows rest in common areas60 to 70 sqft per cow -Bedding should be deep and 1 to 1.5 kg/m2-day Free-stalls (Cubicle) system -Open individual stall, bedded
Effect of cold on production traits
Growth performance -Feed intake -Growth rate -Feed efficiency: feed conversion ratio= feed consumption/BW gain Milk and egg production Carcass composition and meat quality
Heat Production
HP = qr +qc +qd +qe + CvmbΔTb when Tb is constant, CvmbΔTb=0 HP = qr +qc +qd +qe = qsensible + qlatent The metabolism or metabolic heat production (HP) is influenced by muscular activity, eating, and other chemical activities of the animal. HP derived from lab and field experiments The surface area of the animal is a governing parameter for the sensible heat transfer of the animal.
1st law of thermodynamic, conservation of energy law
HP Δt =ΔQ+ ΔI ΔQ = net heat loss by animal to environment, J; ΔI = change in internal energy of the animal, JHP = metabolism or metabolic heat production of the animal, J/time period (J/s= W)Δt = time period, s.
Heat loss of evaporation
Heat transferred as water is vaporized from respiratory passages and skin surfaces. Increasing respiration rate accelerates heat loss. When sweat comes in contact with the skin, a cooling effect occurs as sweat evaporates. The cooled skin serves to cool the blood.
Electric heaters
Heating elements (metals) convert electrical current to heat .I to Heat More efficient Don't generate moisture Not primary heaters for large buildings Used as auxiliaries or for small building
tunnel ventilated houses
High air speed is required for wind-chill during summer- -Air speed at animal level varies ( up to 600 FPM) Use tunnel inlets and fans -Evaporative cooling usually installed at the inlet end for maximum cooling Fans distribution and installation are more difficult.
Fogging systems
High water pressure: 200 psi Moderate/high cost: high pressure stainless steel or PVC pipe, pump Require more maintenances Filtering water and cleaning nuzzles More efficient with adequate ventilation Less water usage and keep floor dry Need to watch relative humidity
Homeothermy
Homeothermy is the condition of a relative constant temperature in the core of an animal's body, where the vital organs reside. -Food mammals (cattle and swine): 38-39oC -Poultry: 41.5oC There exists a temperature gradient from core to shell and from core to extremities. -Organs in the core have higher metabolic rates than do skeletal muscles in the body shell, except during exercise, shivering, or exposure to extremely hot surroundings. The homeotherm's body temperature is relatively uniform and constant. -Various parts of the body do have different temperature. -Body temperature varies from time to time.
Saturation
If the air is SATURATED, it is holding ALL of the water that it can hold. WARM air expands and can hold more water vapor than COLD air, so it takes more water to saturate warm air. If the air is saturated, its Relative Humidity is 100%, and if the temperature drops PRECIPITATION will occur.
Responses to heat stress
Impaired function Drop in production Depressed immune system Decreased reproduction
Basic animal needs and requirements
In the 1960's, discussions about animal welfare led to the basic rights for animals wellbeing established (Brambell, 1965). Animal right to have sufficient freedom of movement to allow it to get up, lie down, groom normally, turn around, and stretch it limbs, without difficulty.
Heat lamps
Incandescent bulb -More efficient to cover electricity to heat -Radiant heat (direct) 100 to 250 W -Number of lamps may be limited due to electrical service; upgrading electrical service may be needed Height adjusted for different covering areas
Extending
Increase surface area Increase heat loss through convection
Companion animal housing
Indoor primary enclosure is generally good for most of animals when secondary enclosure is humane environment Outdoor primary enclosure -It is not recommended that primary enclosures be exclusively outdoors and especially not for very young, old, sick or injured animals. -Structurally sound -Weatherproof -Adequate shade -Ventilation -Clean absorbent bedding -Prefer washable floor (concrete, rubber mats, tile etc.)
Mechanical Ventilation
Inlet and fan location determine air movement pattern Different houses have different ventilation modes based on air movement pattern -Cross ventilated houses -Tunnel ventilated houses
Natural ventilation disadvantages
Lack of control: NV depends on the difference between inside and outside temperature but mostly on the wind, which can change in both speed and direction every few minutes. This mean sa building run the risk of underventilation on calm, hot days and over ventilation on cold days. Building location: Because natural ventilation depends largely on prevailing win currents, a location where wind would be deflected or blocked is unacceptable for a natural system, although it might be ideal from the standpoint of feed and animal handling. Difficult-to-correct problems: A NV building which does not function properly is often difficult and expensive to correct. Sometimes the only solution is to revert to mechanical ventilation.
Cold hardiness of cattle, cow, sheep
Large size and effective thermal insulation Depends on level of acclimatization Large heat increment from digestion and metabolic processes Feed More energy ~1.0 % more energy / 1°C drop below 20 °C. Protect cattle from wind (or ↑25%). Wet and cold climates supply shelter and dry bedding (or ↑ 25%).
Advantages of free-stall housing
Less space per cow needed Bedding cost reduced by up to 75% relative to bedded pack system Less labor required to bed cows Cows are cleaner
Thermoregulation capacity of neonate
Less thermal insulation layers -Hairless -Devoid of subcutaneous fat More heat loss -Large surface area per unit of body weight -Fetal fluid (lambs and calves) Maintain a normal body temperature is highly dependent on their capacity to produce heat. -Carbohydrate and lipids -Stored energy: 425, 600, 1,470 kJ/kg in piglet, lamb, and calf
Common heaters
Liquid propane/natural gas heaters -Forced air heater -Pan brooding -Radiant tube Electric heaters -Heating lamps -Heating mats -Space heater
Heat Balance and Heat Flow of Animals
Living animals use oxygen to burn carbohydrates, fats, and protein in a process called metabolism Metabolism generates heat energy (HP) Heat loss to environment
Horse stable
Low ceiling without ridge vent(air quality is impaired in cold season without adequate ventilation) High ceiling with ridge and eave vent
Sprinkler systems
Low water pressure Low cost On thermostat and timer Good for natural ventilated and tunnel ventilated houses/barns
Humidity Control
Maintain 50-60% RH Need RH sensors to measure accurately RH can be controlled -Normally RH is only partially controller for moisture removal, not for adding moisture -Low RH normally is not controlled unless prolonged dry period (humidifier is required) -High RH should be controlled since high RH could cause heat stress and respiratory track diseases
Control Gases and Dust
Maintain good air quality -<25 ppm NH3 -<5,000 ppm CO2 -<5 ppm H2S -<200 ug/m2 < PM2.5
control moisture
Maintain proper relative humidity50-60% -Too dry = dusty -Too wet --Caked floor --Heat stress in summer --Condensation on structure in winter --Promote molds and bacteria grows --Respiratory disease
Temperature Control
Maintain temperature thermalneutral (thermalcomfort) zone -Need temperature sensors to measure accurately -Feed the measured temperature back to controller (thermostat) -Controller (thermostat) controls heating or cooling devices --Need relays if controller and the devices use different electrical systems, usually controller use low voltage for safety reason -Heating when T > LCT : heaters -Cooling when T > UCT: more fans, sprinklers, foggers, mists, cooling pads
Control Temperature
Maintain thermoneutralZ one that is affected by: Animal species, size, age, sex, Animal numbers
Negative pressure Pressure differential = static pressure
Measured in inches of water column Acceptable range 0.04 to 0.10 inch water Created by fans exhausting air out of house Creates negative internal house pressure Pulling air into the house thru inlets or vents creating air velocity
Cold Environmental Management
Minimize cold stress when environmental temperature is below lower critical limit -Heat generated from animal could not meet the heat required by the cold environment Heating -Enclosures -Environmentally controlled houses No-heating -Outdoors, pasture -Shed and shelter -Naturally ventilated houses
Survival of Neonate
Most critical period2-3 days following birth -Swine, 0-48 h postnatal mortality > 50% of total preweaning loss (5 to 10%) -Lamb, 75% of mortality within the first postnatal day, 50% of the mortality due to cold and cold-induced-starvation. -Calf, 8% vs50% of mortality within the first postnatal day for indoor vs. outdoor born Sudden and dramatic cold stress between dam's uterus temperature and and external temperature -15-20 oC for piglet -25-35 oC for lamb and calf
Type of shade
Natural: trees Permanent: barns and sheds Portable -Wood or metal frame -Roof -Shade cloth -Black -Reduces 80% light
Negative vs. Positive
Negative Advantages: -Air flow pattern control -Lower cost Disadvantages: -Higher energy consumption -Requires extensive caulking and sealing -Backdraft of non-filtered air is a major problem when air filtration is neededEntrance, exit Positive Advantages: -Lower energy consumption -Easier air filtrationBetter biosecurity and disease prevention Disadvantages: -Higher cost -More complex design on air distribution and flow pattern
Cold weather comfort
No cold air drafts (wind-chill) A dry place to lie Plenty of clean dry bedding Plenty of fresh air Minimum frost or condensation during very cold weather
Radiation Heat Transfer
No needs for direct contact or medias between two objects Direct heat transfer between two objects with different surface temperatures Low temperature with longwave radiant heat
No-heating
Outdoors, pasture Shed and shelter• Naturally ventilated houses
Respiratory Evaporative Heat Loss
PantingHorses and cows: sweating > panting -Sheep: panting > sweating -Poultry and pig: panting Negative impact of panting -Respiratory alkalosis (high alkalinity of blood and body tissues) -Hypocapnia: low CO2levels
Mechanical (Power) Ventilation
Positive pressure&Negative pressure
How is Humidity measured?
Relative Humidity is measured using a PSYCHROMETER. A psychrometer is made of two thermometers. One is covered with a wet sock. When air moves over the wet cloth, evaporation occurs and lowers the temperature on that thermometer. If you compare the temperature on the two thermometers you can get the relative humidity from psychrometric chart
Is it possible to predict animal response to heat stress?
Remove or provide extra care for "sensitive" animals -Change environment -Change animal -Reduce heat production -Increase heat loss Identify heat extremes in advance -Change environment -Change animal -Reduce heat production -Increase heat loss Acclimation Program
Good air exchange or ventilation of confinement housing is essential to animal comfort.
Removes •Hot and moist air Increases •Convective heat loss Recommended •> 60 air change per hour
Animal cooling ability is improved by increasing the air velocity over the animal's skin.
Removes •Hot, moist air in contact with the animal Increases •Convective heat loss (wind-chill) •Disruption of the boundary layer Recommended •200 to 600 fpm (1 to 3 mph)
Natural Ventilation
Ridge vent (smoke stack) Sidewall open curtains Narrow shed type
Animal shelter
Space Minimize environmental contamination Heating, cooling and air conditioning (HAVC) Minimize stress and maximize welfare Different requirement for different holding terms for cats -Short term (2-3 wks): Hiding place, Soft sleeping surface, Novel toys < 1 yrold, Free from dog view and noise -Medium term (3 wksto 3 months): interact with human, opportunity to jump, clime and run, scratching post -Long term (> 3 months): exposure to no-threatening stimuli, social interact with other cats, outdoor access
Other housing -calf
Strict ventilation requirement Isolation to prevent pathogen transfer From birth to 1 week post-weaning should be housed individually
Heat mats
Strong plastic 30 to 35 oF ( 16 to 20 oC) above air temperature 20 to 30 W/ft2 Need thermostat and controller to control temperature
Milking facilities
System of milking dictated by housing system -Free stall use parlors Holding area -Confining cows in preparation for milking -Paved, easy cleaned, funneled to parlor -16-17 sqft per cow for larger breeds -Usually combination of forced-air movement and natural ventilation
How to measure thermal environment
Temperature Humidity Air speed Radiation
Cold Environment Conditions
Temperature < lower critical temperatureStressor Energy expenditure Feed intake Production performance
Thermal environment
Temperature and humidity Thermoneutralzone -Species, age, sex Thermal environment management -Cold stress: Heating -Heat stress: Cooling
Relative Humidity
The amount of water in the air compared to the amount of water the air could possibly hold. Humidity values are usually given as Relative Humidity. Examples: If the air is holding half the water it could hold, it's Relative Humidity is 50%. If the air is holding ALL the water it can hold it is saturated and the relative humidity is 100% If the air is holding no water, relative humidity is 0% If it holding a quarter of the water it could hold, 25%
macroenvironment
The physical environment of the secondary enclosure—such as a room, a barn, or an outdoor habitat
Thermal Indices for Animals
The requirement of environmental management. Driving force for heat exchange between the environment and animals Dry-bulb temperature: sensible heat Humidity (relative humidity): latent heat Thermal radiation: sensible heat Air flow: sensible and latent heat Temperature only is not enough!!! Two or more thermal measures are combined and used to represent the influence of sensible and latent heat exchanges
heat stress Physiological changes
Thermal status General effects Immune condition Nutritional status Behavior Endocrine Reproductive status
Wet bulb temperature (WB)
Thermometer with wet sock WB temperature is always less than DB temperature because = dry bulb temperature minus the amount of evaporative cooling except at saturation (100% relative humidity) when = DB temperature
Dairy sprinklers
Thermostat: Air temperature> 75°F 15-min cycle: 3 min ON: 12 min OFFPressure: 40 PSI Cover range: 6 ft2/ftlineWetting rate: 0.03 gal/ft2/cycle Pipe size: based on flow rate Nozzle size: 0.5 gal/min Nozzle pattern: 180 and 360 degree Nozzle distance: 80 to 95 % of spray diameter Operating: 8 to 12 hrper day over 100 to 150 days per yr Cost: material < $5/ft; daily water $1.5 / 100 ftLife: 5 yr
Housing for cows
Tied housing systems for small herds -Restricts the cows freedom of movement and activities (standing, lying, feeding, milking, etc.) -Less comfort -For small herds with limited labor (likely only owner) Loose housing systems -For middle to very large sized herds -Comfort for animals and stockperson -Lying area -Feeding passage or area -Standing and walking passage/area -Milking area
Swine housing system
Vertical Integration of the Swine Industry -One company controls, through ownership or contract relationships, from the farm to the fork -Improved herd performance -Production efficiency -Fewer & bigger hog farms -Contracting -Globalization
Water improves animal cooling through evaporation.
Water consumption •Increase in hot weather Sprinkling systems •Wet skins •Increase direct evaporation Fogging and evaporative cooling pads •Cools air directly •Animal cooled by cool air
Evaporative cooling process
Wet-bulb depression: the difference between the dry-bulb and wet-bulb temperatures(Twb-T1). Evaporative efficiency: η=(T1-T2)/(T1-Twb)x 100% Evaporative cooling pad / fogging efficiency: 50 to 75% Evaporative cooling is far more effective under hot and dry condition than under humid condition.
Humidity
Wet-bulb psychrometer -Low cost and reliable Hair hygrometer -Low cost and need calibration -Low accuracy Electronic humidity -Semiconductors -Acoustic wave sensor -Chill mirror hygrometer
Evaporative exchange
When (Tambient-Tcorebody temperature) >= 0, heat loss is from evaporation only. Cutaneous evaporative heat loss -Sweating and passive (diffusion)evaporation from skin Respiratory evaporative heat loss -Panting
Wind protection
Wind breaks/Wind fences Shelters, shed, hutches Openings should not face to prevailing wind Natural ventilated houses Close curtains and keep minimum ventilation to maintain good air quality
Heaters - Pan brooder
capacity: 25,000 to 40,000 BTU (5.8 to 12 kWhr) Environmentally controlled house Need ventilation to bring fresh air and remove toxic gases Animals -Pullets -Broilers -Turkeys -Nursing pig
Evaporation
he loss of heat from a liquid's surface that is losing some molecules as gas can only occur if surrounding air is not saturated with water molecules For each liter of water vaporized, 580 kcal transferred to the environment. Need 305 W heat if one lb water evaporate in one hour.
convection
heat transfer that occurs between a surface and a fluid (at rest or in motion) when they are at different temperatures •Conduction and convection both require the presence of a material medium but convection requires fluid motion. •Convection involves fluid motion as well as heat conduction. •Heat transfer through a solid is always by conduction. •Heat transfer through a fluid is by convection in the presence of bulk fluid motion and by conduction in the absence of it.
Thermal radiation
heat transfer that occurs between two surfaces at different temperatures. It results from the energy emitted by any surface in the form of electromagnetic waves. All materials radiate thermal energy in amounts determined by their temperature, where the energy is carried by photons of light in the infrared and visible portions of the electromagnetic spectrum.
Thermal conductivity, kproperty of the material
k diamond-very high: perfect heat sink, e.g. for high power laser diodes k animal-low: core temp relatively constant k air-very low: good insulator* home insulation* woolen clothing* windows double glazing
Behavioral responses
recruited first because they occur quickly and usually do not require much energy ↓ Grazing Time ↑ Lethargy ↑ Shadow or shade seeking ↑ Body alignment with solar radiation ↑ Standing time ↑ Crowding water trough and splashing ↑ Agitation and restlessness
Electric space heaters
size: < 1,500 W Safety is primary concern!!! Animal safety -High temperature on electric coils and heating surface -High voltage and electric leak under moist environment Fire hazard: short circuit under dust and moist environment
Convection heat transfer
strongly depends on the fluid properties dynamic viscosity, thermal conductivity, density, and specific heat, as well as the fluid velocity. It also depends on the geometry and the roughness of the solid surface, in addition to the type of fluid flow (such as being streamlined or turbulent). Newton's law q"convection=h(Ts-T∞) q" = heat flux in W/m², h= convection heat transfer coefficient, W/m²·C,Ts=surface temperature, C T∞= temperature of the fluid sufficiently far from the surface, C
Upper critical temperature
the ambient temperature above which the rate of evaporative heat loss of a resting thermoregulating animal must be increased in order to maintain thermal balance (or where an increase in metabolic heat production is observed in some endotherms from the muscular expenditure of panting).
Dew Point
the temperature at which condensation will occur. The Dew point is the temperature the air must be in order to be saturated. Remember, cooling the air makes it unable to hold as much water vapor, so water will condense out at a certain temperature. Always equal (saturated air) or lower than WB temperature (not saturated air)
Conduction
the transport of energy in a medium due to a temperature gradient Diffusion of thermal energy through a continuous, frequently stationary medium, and depends on properties of that medium. Heat transfer between non-moving matter Within a matter or between two touching matters solid to solid, solid to unmoving fluid, unmoving fluid to unmoving fluid Fluid is liquid (like water) or gas (like air)
Heat transfer
thermal energy in transit due to a temperature difference. Whenever there exists temperature difference (ΔT≠0) in a medium or between media, heat transfer must occur.
Change in internal energy
ΔI/ Δt = CvmbΔTb Cv = specific heat of body mass at constant volume, J/(kg °C); mb = body mass, kg; ΔTb = change in body temperature, °C or K. ΔI=0 for homoeothermic animals
Heat loss from the animal
ΔQ/ Δt = qr +qc +qd +qe qr = radiant heat transfer; qc=convective heat transfer; qd =conductive heat transfer; qe = evaporative or latent heat loss
Thermal Status
↑ Core body temperature (total Body Heat Content) ↑ Respiration rate and respiratory evaporative heat loss ↑Skin temperature, blood flow, and sweat Rate ↓Blood flow to internal organs ↑Salivation, drooling, and panting rates ↑Dehydration ↓Heat loss via radiant, conductive, and convective
General effects
↑ Heart and pulse rates ↑ Hyperventilation ↓Blood carbon dioxide (CO2) ↓Blood bicarbonate ↓Blood buffering capacity ↑Respiratory alkalosis (pH > 7.5) ↑ Urinary sodium and bicarbonate excretion ↓ Hepatic portal blood flow ↑ General Vitamin E deficiency
Endocrine
↑ Hormones Linked to Metabolism -Thyroxine, Somatotropin, Cortisol ↑ Hormones linked to water and electrolyte metabolism -antidiuretic hormone, aldosterone ↑ Catecholamines- epinephrine and norepinephrine ↑ Prolactin and ↓ prolactin receptor numbers ↑ Leptin ↓ Insulin ↓ Blood Glucose
Reproductive Status
↓ Breeding efficiency and conception rate ↑ Fetal and postnatal mortalities + ↓ Calf Birth Weight ↓Semen Quality •↓ Sperm Motility •↑ Percent Abnormal and Aged Sperm ↓ Estrous Activity •↓ Estrous Duration •↓ Heat Detection ↓ Uterine Blood Flow •↓ Placental weight and growth + ↑ retained placenta •↓ Gestation period •↑ Labor and delivery difficulties
Nutritional Status
↓ Dry matter intake (DMI), weight gain or growth, condition score, and blood glucose level ↑ Energy requirement for maintenance ↑ Salivation ↓ Saliva to rumen ↓ Salivary bicarbonate pool for rumenal buffering ↓ Rumen pH ↑ Acidosis ↑ Potassium loss from skin ↑ Dietary requirements for potassium and sodium ↑ Urinary nitrogen loss ↑ Water intake
Immune status
↓ Immune function ↑ Susceptibility to parasitic and nonparasitic diseases ↑ Mastitis ↑ Somatic cell count ↑ Plasma antibody -Immunoglobulin concentration ↑ Death
Milk production
↓ Milk production ↓ Mammary blood flow ↓ Mammogenesis ↓ Lactation peaks ↓ Milk component levels
