Effect of Chronic Heat Stress on Broiler Performance in Jordan

Abstract

An experiment was conducted in the poultry farm of the faculty of agriculture in the campus of Jordan University to evaluate the effect of heat stress on the performance and some physiological parameters of 4-8 week old Isa Vedette broilers. Environmental temperatures in controlled environmental rooms were constant 25 (control), 30 and 35±2^oC, in addition to a variable-natural temperature, 24 - 28 ± 2°C in the open-sided poultry house. At the end of the experiment, a representative sample was randomly selected from each treatment and exposed to heat tolerance test at 40±2^oC in the environmental physiology lab. The results showed that, growth rate, body gain, feed consumption and feed efficiency were significantly (p< 0.05) reduced of 4-8 week old broilers reared in hot-closed environment (30 and 35±2^oC) and variable-natural temperature in open-sided environment. The heat tolerance test showed that, broilers reared at high environmental temperatures of 30 and 35±2^oC had lower mortality rate and RITr than those reared at constant 25±2^oC and variable-natural temperature (24 - 28^oC) in closed and open-sided environment, respectively. Finally, it could be concluded that, environmental temperature above 25^oC has a significant (p< 0.05) negatively effects on the performance of 4-8 week-old broilers reared in open-sided poultry house particularly, during summer season. Moreover, it will increase the market age and increase the productive cost. On the other hand, broilers reared in hot environment may improve their heat tolerance, which might acquire during the acclimation at high environmental-rearing temperature.