SUMMARY: The aim of this study was to evaluate the effect of increasing incubation temperature of Araucana hen eggs on embryo mortality, hatchability,chick, yolk sac and internal organs weight. Eggs (n= 426) were randomly distributed into: a) Control group (n= 215), which were incubated at 37.5 °C for 21 days or b) Experimental group (n= 211), which were incubated at 39.5 °C, for 18 days and then at 37.5 °C for the remaining 3 days. In both groups eggs were incubated with a relative humidity of 55 %. The embryo mortality rate was greater (P ≤0.05) for the experimental than the control group (44.1 vs. 14.9 % respectively). On the contrary, hatching rate was greater (P ≤0.05) for the control than the experimental group (97.8 vs. 80.5 % respectively). The average weight of chicks, at 36 h of age, was lower (P ≤0.05) for the experimental than control group (36.3 vs. 37.01 g respectively). Also, increasing incubation temperature reduced (P ≤0.05) internal organs weight of chicks in the Experimental compared to Control group. On the other hand, yolk sac weight was reduced (P <0.05; 2.5 vs. 6.2 g for Control and Experimental group respectively). We conclude that increasing the incubation temperature of Araucana hen eggs up to 39.5 °C for 18 days has a negative effect on embryo survival, hatchability, chick and internal organs weight and absorption of yolk.

KEY WORDS: Araucana hen; Incubation; Embryo mortality; Hatchability; Chick weight.