Figure 1. Effect of Temperature and Humidity 20 25 30 35 40 45 50 75 100 Relative Humidity, % Danger high mortality High stress Moderate Comfort Cool Temperature, ° C Figure 1. Effect of Temperature and Humidity on Poultry Heat Stress 1

Convection and radiant heat Figure 2. Energy and Heat Flow in Poultry Convection and radiant heat Evaporation heat loss from respiration Radiant heat Energy in feed Water intake (temperature important) Growth Activity Metabolic heat Conduction heat loss to litter and concrete Excreta heat and energy (loss of bicarbonate and potassium 2

Respiration Rate (breaths/min) Figure 3. Effect of Respiration Rate and Time on Stress 6 5 NORMAL 4 High Stress Hours 3 Stress High Mortality 2 1 20 100 120 140 160 180 200 220 Respiration Rate (breaths/min) 3

Figure 4. Effect of Heat Stress on FCR in Broilers Time Temp RH days °C % FCR Exp 1 21-42 24 30 1.97 21-42 23-38 30-20 2.16 Exp 2 32-46 22 40 1.96 32-46 27-32 70-50 2.57 4

Figure 5. Economics of Heat Stress in Broilers Savings, heat stress vs normal temperature at various feed costs Average $53 $70.70 $88.38 $106 $124 50 100 150 200 250 300 350 Exp 1 $66 Exp 2 $182 $56 $47 $38 $28 $78 $104 $130 $156 Savings per 1,000 birds, $ Average Feed cost $/MT 5

Figure 6. Open Broiler House with Concrete Floor bird mesh White or reflective roof E N S 3 m min 35 °min W insulation 2.75 m grass bird mesh and roll down plastic curtains 1.75 m concrete floor 12 m max drain 6

Figure 7. Open Broiler House with Slat Floors bird mesh white or reflective roof E 3 m min N S 35 °min W insulation bamboo or wood slat floor with 2.5 cm solid and 1 cm open 2.75 m gap to prevent rat entry bird mesh and roll down plastic curtains 1.75 m 1.75 m 12 m max metal rat guards sloping earth drain cement footings treated timber supports stairs or ramp 7