By: C. E. Heat Stress in Poultry

Staying cool Optimum temperature is 21-24 degrees C No sweat glands Evaporation of water from surfaces of the lungs and air sacs Water evaporates Rate of evaporation increases as temperature increases

Hot and Humid Conditions Drink more water Respiratory rate increases (20 to 240 breaths per minute) Seen as panting Extra waste produces Drinking water removes extra waste

Humidity When above 50%, there is no marked reduction in heat loss from the lungs Only a few grams evaporate before the air is saturated

Wet Droppings Normal: firm, brown and white Abnormal: wet, frothy, foamy, yellow Caused by heat stress from hot and humid environmental conditions Decreased appetite Increased water consumption Treatment: Add vitamins and electrolytes to plenty of cool water Stand in cool water Fan blowing Shade Mash feed with cool water

Responses Panting Evaporative cooling Loss of water from lungs 20-250 breaths/min Respiratory (metabolic) alkalosis- loss of CO2 and HCO3 (bicarbonate) Plasma pH up to 8.0 Intracellular pH to acid and potassium is lost Weaker egg shells (calcium+CO2)

How it works

Responses Spread Wings Radiate heat from body to ground Lets circulating air reach the hotter parts of their body

Responses Stop Eating/Drink More Shunts Blood Away from Gut Lower metabolic heat Cool body through the gut Shunts Blood Away from Gut Reduce metabolic heat

Signs of Heat Stress: What to Look For Labored breathing and panting Pale combs/wattles Lifting wings away from body Lethargy Diarrhea Seizures/convulsions

Prevention Access to water Supplement electrolytes Protection from sun Don’t crowd Feed during cooler times Keep birds calm

Resources https://www.heatstress.info/HeatStressExplained/BodyHeatregul ationinPoultry.aspx http://www.poultryhub.org/physiology/body-systems/respiratory- system-thermoregulation/ https://www.vetpoultry.com/blogs/barn-talk-livestock-health-and- nutrition/how-to-spot-signs-and-prevent-heat-stress-in-chickens https://www.heatstress.info/heatstressinfo/Heatstressincattlepoul tryandswine/BiochemistryofdietaryelectrolytebalanceinPou/tabid/ 2214/Default.aspx