環(huán)境因子對(duì)動(dòng)物生產(chǎn)之影響課件

1、環(huán)境因子對(duì)動(dòng)物生產(chǎn)之影響課件環(huán)境因子對(duì)動(dòng)物生產(chǎn)之影響課件Engineering Fundamentals：part II Impact of Environmental factors to the animalImpact of TemperatureImpact of HumidityQT, Qs, QLTHI and MPDImpact of Air VelocityImpact of RadiationBGT and WBGTEngineering Fundamentals：part TemperatureLCT, Neutral zone, UCTAdapted from ASHRA

2、E Fundamentals, 2019TemperatureLCT, Neutral zone, Air temperature, oCImpact of TemperatureAdapted from ASHRAE Fundamentals, 2019Growth rateEnergy EfficiencyAir temperature, oCImpact of TAdapted from ASHRAE Fundamentals, 2019From -14 to 24 oC No impact in MPAdapted from ASHRAE FundamentaMilk Producti

3、on Decline at T25 oCAt 30 oC, MP reduced by 25%At 35 oC, MP reduced by 50%Milk Production Decline at T2Known factsOptimum Temperature zonefor mature Holstein cows: 10 20 oCfor new born: 10 15 oCMilk Production Decline at T25 oCTemperature of Tainan, Taiwan (based on 1981-1994 hourly weather data)Pro

4、bability of T= 15 oC is 9.3% Probability of T 25 oC is 39.63%Probability of Twb =25 oC is 32.1%Probability of Twb =26 oC is 20.27%Probability of Twb =27 oC is 9.02%Probability of Twb =28 oC is 2.15%Known factsOptimum TemperatureImpact of HumidityTdb ()RH (%)HolsteinCowJerseyCow2438100100247696993446

5、636834804156Relative MPAt high T, impact of RH is severe.Impact of HumidityTdb ()RH (%Total heat loss per unit body mass, in W/kgAdapted from ASHRAE Fundamentals, 2019Total heat loss per unit body 400 450 kg breeding age (20 months)Holstein Dairy Calf 600 kg MatureAdapted from ASHRAE Fundamentals, 2

6、019400 450 kg breeding age (20500 kg Cow = 1 kW heater, producing1.2 kg water/min 24 oCAdapted from ASHRAE Fundamentals, 2019500 kg Cow = 1 kW heater, prQTQSQSAt high temperature, latent heat is dominatedHeat Output: Qs+QL=QTAdapted from ASHRAE Fundamentals, 2019QTQSQSAt high temperature, latAt high

7、 temperature, heat dissipation is dominated by latent heatQTQTQLQLAdapted from ASHRAE Fundamentals, 2019At high temperature, heat diss% of QL in QTAir temperature, oCQL QTAdapted from ASHRAE Fundamentals, 2019% of QL in QTAir temperature, At least 1.2 - 2 kg of water evaporated from skin for 500 kg

8、Calf per hour 30 oCAdapted from ASHRAE Fundamentals, 2019At least 1.2 - 2 kg of water eAt least 0.3 0.5 kg of water evaporated through respiration for 500 kg Calf per hour 30 oCAdapted from ASHRAE Fundamentals, 2019At least 0.3 0.5 kg of waterShort SummaryQT= 1 kW for 500 kg cattleQL/QT = 70% - 100%

9、 when Tdb 30oCWithin QL, through respiration: 20-25%, others through skin.Evaporative cooling method should not increase the humidity of the environment around cattle (0 to 1.5 meters above ground). Short SummaryQT= 1 kW for 500Index combining Temperature and HumidityTHI = T (in oF) 0.55 * (100-RH%)

10、/100 * (T 58) (English unit)THI = Tdb (in oC) + 0.36 * Tdp (in oC)+ 41.2 (Metric unit)Temperature Humidity Index (THI) T, TdbRH%TwbTdpTHI78.8 oF=26 oC 45%17.7 oC13 oCTHI=72.50 (Ingrahams eq.)THI=71.88 (Armstrongs eq.)104 oF=40 oC 100%40 oC40 oCTHI=104 (Ingrahams eq.)THI=95.6 (Armstrongs eq.)Index co

11、mbining Temperature anTHI = f(Tdb, RH)THITHI = f(Tdb, RH)THITHI = f(Tdb, Twb)THITHI = f(Tdb, Twb)THIImpact of HumidityTdb ()RH (%)HolsteinCowJerseyCow2438100%100%247696993446636834804156Relative MP68.33THI72.1782.6286.01THI = 70, MPD occurred， THI 80, severe MPDMPD is not linear depend with THI.Impa

12、ct of HumidityTdb ()RH (%THI90, no recoveryAdapted from ASHRAE Fundamentals, 201975.7379.9663.765.0572.3268.4763.3976.6890.0987.0988.0664.3164.6582.4986.0182.0982.3684.21THI90, no recoveryAdapted froMPD = 1.08 - 1.736 NL + 0.02474 (NL) (THI) THI increased, MPD increased. Especially severe for high N

13、L cattle. Adapted from ASHRAE Fundamentals, 2019MPD = 1.08 - 1.736 NL + 0.0247Milk Production=f(HD74, HA80S)MP = 21.48 0.051 * HD74 0.0099 * HA80Swhere，MP: Milk production (in kg/day/cow)21.48: daily production (in kg) per cow in normal weather conditionHD74: total hrs of THI 74 for previous 4 daysH

14、A80S: square of total hrs of THI 80 for previous dayLinvill and Pardue (1992)Milk Production=f(HD74, HA80S)Impact of Wind VelocityWind Velocity10 oC26.7 oC35 oC0.18 m/srMP =100%(Teq,wc=10) rMP =85% (Teq,wc=26.7)rMP =63%(Teq,wc=35)2.44 m/s100% (8.3)95% (26.2)79% 4.02 m/s100% (5.3)95% (25.4)79% Wind C

15、hill Index = (10.45+10*V0.5 V) * (33 Ta) Teq,wc= - 0.04544*WCI+ 33 for 19.4 m/s V 1.8 m/sTeq,wc = Ta for V = 1.8 m/sImpact of Wind VelocityWind VeEquilibrium Wind Chilled TemperatureEquilibrium Wind Chilled Tempe環(huán)境因子對(duì)動(dòng)物生產(chǎn)之影響課件環(huán)境因子對(duì)動(dòng)物生產(chǎn)之影響課件Warm water insideWarm water insideThe Equilibrium Wind Chill

16、ed Temperature equationdoes not imply cooling to below ambient temperature, but recognizes that, because of wind, the cooling rate is increased as though it were occurring at the lower equilibrium wind chilled temperature under calm wind situation.The Equilibrium Wind Chilled TImpact of Radiation Ra

17、diationRelative MPCal/cm2/minW/m27.2 oC21.1 oC26.7 oC0.2140100%100%92%0.4229410093770.642010090690.845881008857Impact of Radiation RadiationRBlack globe temperature (BGT) Index combining Temperature, Radiation and Wind but no Humidity.Used in studying the effects of shading and/or ventilation.Effect

18、s of forced ventilation on dairy cattle by Berman (1985).BGT 36, the increase of RT is in direct proportion to the increase of BGT. With forced ventilation, the rate of rectal temperature increment can be reduced by half. Black globe temperature (BGT) Index combining Temperature, Radiation, Wind and Humidity.Wet bulb globe temperature (WBGT) WBGT_indoor = 0.7 * Tnv,wb + 0.3 * BGTWBGT_outdoor = 0.7 * Tnv,wb + 0.2 * BGT + 0.1 * Tdb Determined by