Abstract
In this paper was investigated influence of seasons on chemical composition of egg albumen, yolk and eggshell in eggs from laying hens. The reasons for this research were the higher summer temperatures in Republic of Macedonia which causing severe damages in production of eggs. Isa-Brown hybrid hens were tested in a poultry farm located in southern part of state where penetrate the Mediterranean climate and the summer temperatures reach a maximum of 35-41°C. The research was lasted 3 seasons (summer, autumn and winter) during which time were processed about 900 eggs and in 176 eggs was determined the impact of fixed factor on the chemical composition of albumen, yolk and shell (moisture and dry matter, crude ash, crude protein, crude fat and calcium carbonate). The obtained results were statistically processed by applying different models of Least Squares Means by Harvey, 1990. Factor season has shown no statistically significant impact on chemical composition of albumen and yolk in any studied parameters. Although, there was a slightly lower percentage of crude protein in albumen and a higher percentage in yolk during the summer. In contrast, season had statistically significant (p<0.01) influence on the percentage of calcium carbonate in eggshell. The analyzed eggs collected during the summer months had a significantly lower (90.74) percentage of CaCO3 in shell compared to eggs collected in autumn (92.01) and winter (93.86). That is a one of the reasons for poor quality of eggs in the summer seasons.
Key words: season, chemical composition, albumen, yolk, eggshell
