ISSUE FOCUS 42 FEED & ADDITIVE MAGAZINE June 2022 “To help birds survive heatwaves, they should not only be kept under the best possible living conditions, but their water-electrolyte metabolism should also be supported. Environmental changes would streamline the thermoregulation processes, and adequately selected feed additives would prevent water and electrolyte loss.” Poultry house temperature, together with other microclimatic factors such as humidity, air velocity, concentration of harmful gases like NH3, CO2, H2S, light intensity and dust significantly affect the poultry's health and productivity. Keeping an adequate air temperature in the poultry house to prevent the overheating of birds is particularly important in the summer season. A too high ambient temperature increases their sensitivity to pathogens present in the environment, such as bacteria and fungi, and risks their bodies overheating (hyperthermia). For broiler chickens, commercial laying hens, and parent flocks of broiler chickens and turkeys, the optimal temperature range is between 15-25ºC. The ambient temperature exceeding 27-30ºC can cause heat stress in the birds. The consequences of this heat stress in laying hens include reduced egg yield and thinner eggshells due to impaired calcium ion transport and elevated blood pH values. In broiler flocks, a reduced live weight gain of up to 20g was observed and attributed to reduced feed consumption. The mortality rate increases too, and it most frequently concerns the heaviest birds. In the birds’ environment, unfavorable changes also occur, with litter humidity increasing because of dilution of droppings due to higher water consumption. That, in turn, can cause an increase in relative air humidity, which in a poultry house should not exceed 6570%. All the factors mentioned exert a significant influence on the productivity in poultry farms during periods of high ambient temperatures. THERMOREGULATION IN BIRDS Birds have developed several thermoregulation mechanisms that protect them against both excessive heat loss and overheating. The dissipation of the excess heat produced due to metabolic processes and movement occurs through the skin and respiratory tract. The difference in temperatures between the bird’s skin and environment, e.g., a building’s walls, floor or ceiling, makes it possible to radiate the heat accumulated in the body. By raising their wings, birds increase radiation from less feathered body surfaces. Too high stocking density hinders heat exchange between birds and the environment, which reduces the effectiveness of radiation. PREPARING POULTRY FOR HEATWAVES Paulina Abramowicz-Pindor, PhD Department of Research and Development AdiFeed Co Ltd.
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