Correlation between egg quality parameters, housing thermal conditions and age of laying hens

High environmental temperatures cause a decrease in feed consumption by laying hens and, as a consequence, a reduction of productive performance and egg weight. The hens age is a factor influencing the albumen quality that tends to be more liquefied in older hens. Such variable is analysed by the determination of the Haugh Unit. The correlations between the egg quality variables (egg weight and Haugh Unit), the thermo-hygrometric conditions in the facility and the age of laying hens were determined in the study and evaluated based on the Pearson correlation coefficient (r) and their significance at the 5% level. The microclimatic data and the eggs were collected in 20 points of poultry facility with birds of 43, 56, 69, 79 and 86 weeks of age, totalling 100 samples. The results show significant correlations between egg weight and temperature (r = -0.238), egg weight and hens age (r = 0.310), Haugh Unit index and hens age (r = -0.256); a non-significant correlation between the quality parameters with the relative humidity of the air inside the barn. The egg weight had a weak negative correlation with the ambient temperature and a weak positive correlation with the hens age. Concerning the Haugh Unit, a weak negative correlation with the age of the animals was found. The weak or non-existent correlation of temperature with egg quality parameters can be due to the environmental conditions that remained in the range of thermal comfort for the animals during the trials.