Özet:

The experiment was conducted during the summer production cycle. Broiler chickens kept on litter – group I and on litter with access to pasture – group II. Throughout the experiment, mortality were recorded. During the second rearing period, when outdoor temperatures were high, radiation and rectal temperature was measured in birds, and blood was collected to determine the levels of thyroid hormones, glucose, corticosterone, and hematocrit. Broiler chickens from group I were characterized by higher mortality compared to group II. In group I, rectal temperature was found to increase during the 6th week of rearing. In broilers from group II, T3 decreased and T4 increased with an increase in air temperature. The lower body temperature of broiler chickens and the smaller proportion of dead chickens in the group with outdoor access may suggest that this housing system helped to increase the thermal comfort of birds during the summer heat. It can therefore be concluded that housing with outdoor access improves the welfare of broiler chickens exposed to heat stress.

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