Effect of induced heat stress on some of eggs quality criteria in commercial laying hens

Production of high quality eggs is an important subject in the egg industry and egg shell characters have roles on the egg quality. There are many factors that affect the egg shell quality such as: layers breed, age and diet, producing period, molting, infectious diseases and stresses, specially heat stress. In this study the effect of induced heat stress on some of eggs quality indices in white leghorn layers (Hyline W-36) were studied. Atotal 80 white leghorn hens were divided in two groups including control and heat stress groups in the same condition of egg and diet. Heat stress condition induced via increasing in bird's environment. Produced eggs from two groups were collected and 20 eggs were then chosen randomly for each group weekly. Then samples examined for eggs quality parameters. Results of this study showed a significance decrease (P 0.05) in the egg's weight, egg's size, egg's shell weight, egg's shell thickness in heat stress group compared to the control group. Also eggs shell's ash percent and eggs shell's calcium percent in heat stress group decreased significantly compared to the control group. In addition, comparison of eggs quality indices showed that negative effect of heat stress increased due to heat stress continuation. This study shows the effect of heat stress on eggs quality as a routine stress condition in commercial layer flocks.