The influence of origin and age of ducks on egg morphological composition and level and activity of lysozyme

The purpose of the study was to evaluate the effect of origin and age of ducks on physical and morphological composition of eggs, as well as determine the level and activity of lysozyme. Eggs taken from three (3) breeding flocks of Pekin-type ducks were studied: P-9 (Pekin of French origin), K-2 Mini-duck, and LsA (Pekin of English origin - synthetic line). Eggs were collected from birds that were in the 13th week of reproduction of the first and second year of laying. In a given research period, 90 eggs were randomly selected for evaluation from each analysed duck flock, always up to 24 h after laying. A total of 540 duck eggs (first and second laying seasons) were analysed. The results showed significant differences (p < 0.05 and p < 0.01) in the evaluated egg parameters between the three experimental groups of ducks. The effect of the genetic origin of the ducks was significant (p < 0.001) on all studied egg traits, except for the percentage of albumen. Older ducks laid eggs with more (p < 0.05) elongated shape and favourable albumen quality parameters (height and Haugh units). The effect significant (p < 0.001) of duck age on albumen height, Haugh units, yolk pH, shell colour and porosity was observed, as well as the effect of origin × age interaction on egg weight, surface area and shape index, albumen and yolk pH, and shell parameters (colour, weight, porosity, elastic deformation). Eggs from ducks in the second period of laying were characterized by the significantly highest (P ≤ 0.01) content and activity of lysozyme. There was an effect (p < 0.001) of origin, season of use and interaction between these factors on the content and activity of lysozyme.