Heat stress in poultry In poultry, 70% of heat is exchanged via convection, conduc- tion or radiation at temperatures between 10°C and 28°C. Once temperatures rise above 28°C, 80% of this heat ex- change in poultry is through panting. The physiological effects of heat stress reduce gut integrity and the birds’ antioxidant status. Combined with the excessive increase in body temperature, this results in reduced meat quality in broilers and reduced egg weight, production and eggshell quality in layers. Mortality rates also increase.
Tackling heat stress Mitigating heat stress is multifactorial and is a combination of environmental control, farm management and nutrition.
Solutions for dairy Managing heat stress in dairy cattle of all ages requires well- ventilated buildings and, for outdoor systems, areas of shade. Adequate supplies of clean water and plenty of trough space are essential. Efficient fans should be used to keep the air circulating in buildings – particularly in collecting and milking areas. And feed should be fresh and pushed up
Figure 1 - Consequence of heat stress on lactating sows. Effect on feed intake and milk production
100
Daily feed intake Daily milk yield Piglet weight at 21d
40 50 60 70 80 90
18°C Quiniou et Noblet, 1999 ▶ HEAT STRESS | MAY 2021 33 22°C 25°C Temperature in farrowing room (°C) 27°C 29°C
(% of values measured at 18°C)
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