The effect of season on internal quality of backyard turkey eggs using discriminant canonical analysis

This study is aimed to define the effect of season on internal turkey eggs produced in backyard systems. To this goal, a total of 197 turkey eggs from Andalusian hens were continuously collected throughout 15 months to study internal quality attributes. A discriminant canonical analysis was performed considering season as the dependent variable and these quality attributes as independent variables. Yolk weight was discarded from analysis due to multicollinearity problems (VIF > 5), and then, statistically explanatory variables were obtained (p < .05). All colour yolk traits, including yolk colorimetric (lightness, redness and yellowness axes) and DSM® fan performed as discriminating variables. Moreover, the yield of egg components (yolk diameter and albumen weight) and almost every shell trait (shell strength, thickness and resistance area) were powerful explanatory variables as well. Albumen height and pH were reported explanatory variables, but possibly due to the effect of the environment from laying to egg collection. Results obtained show a great adaptation of this genotype to its traditional environment and rearing conditions. This study provides the first description of the effect of season on internal food quality attributes of turkey eggs and would provide a better understanding of egg production in organic-like systems. Moreover, the results of this study represent a step forward in the procedures for the institutional recognition of the breed.Highlights Internal egg quality attributes in turkey species vary throughout seasons and serve as explanatory variables in the discriminant canonical analysis. Eggs laid in different seasons can be successfully classified attending to the variance of their internal egg characteristics. Yolk colour attributes, particularly yolk yellowness (b*), showed great explanatory properties, which evidences different trends in pasture availability and consumption during the year. General internal quality did not decline during the summer, which evidences the great adaptation of the Andalusian turkey breed to its environment. Effects of climate change are visible in egg quality in organic-like rearing systems.