Hens of the laying hybrid Shaver Starcross 288 were used in two consequential experiments. The first experiment (for 10 months) was conducted on hens at the age from 18 to 60 weeks (1^st cycle; <i>n</i> = 50) and moulted hens after 10 months laying from 70 to 110 weeks of age (2^nd cycle; <i>n</i> = 50). For the second experiment (for 8 months) in the 1^st cycle 18 weeks old hens were bought (<i>n</i> = 60) and hens from the first experiment after moulting were used in the 2^nd and 3^rd cycle (<i>n</i> = 32 and <i>n</i> = 28). During the experiments eggshell qualitative parameters and calcium utilisation (%) were determined. The results indicate that the percentage of eggshell decreased with the increasing number of cycles. The significant correlation of the eggshell proportion and the age of hens was higher in long, advanced cycles (<i>P</i> < 0.05). The shell strength in both experiments decreased slightly in relation to the age of hens and repeated laying cycles. The shell deformation had an opposite trend to the shell strength, i.e. it increased with the increasing laying. The average shell thickness showed a decrease in the repeated laying cycles, more significant in shorter cycles (<i>P</i> < 0.01). The specific shell gravity maintained balanced values both in cycles and by the age of hens. The shell density in all cycles in both experiments showed a decreasing tendency in relation to the age of hens. In dietary calcium utilization for the shell formation a significant decrease was recorded in the second cycles after moulting (<i>P</i> < 0.05).

Extracellular polysaccharides (EPSs) produced by algae can be applied in numerous branches of industry, depending on their origin and properties. In this work, the EPS produced with green microalgae Dictyosphaerium chlorelloides was studied by Fourier transformed infrared spectroscopy (FTIR) and atomic force microscopy (AFM), which enabled the characterization of its nanostructure. It was observed that the nanostructure of this exopolysaccharide self‐assembly depends on its concentration. At a concentration of 1 mg/mL the EPS formed a regular and porous matrix on mica, where fibers were cumulated in bundles of 50–70 nm wide. In a more diluted concentration of 10 μg/mL single molecules created a regular network with numerous branches. An average height of molecules was in the range of 400–800 pm with occasional local increase of the skeleton height which can be a result of an interconnection of the fibers. Analysis of the FT‐IR spectrum showed that the EPS has a structure of α‐glucan with the dominance of the galactose and rhamnose residues.

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