The aim of this study was to compare the blood plasma mineral profile (Ca, P, K, Mg, Zn, Cu and Se) and egg-shell quality (eggshell weight, eggshell breaking strength and thickness) of laying hens housed in three different housing systems (traditional cage system, enriched cage system and deep litter system). In each housing system, 12 ISA Brown laying hens were observed during the laying period from week 22 to 75 of age. The effect ( p < 0.05 and p < 0.01) of age and/or phase of the laying cycle on all mineral concentrations was determined. Eggshell breaking strength decreased ( p < 0.001) with the age of birds. The results of this study indicate that the housing systems compared had no significant effect on the blood plasma mineral profile of laying hens under study and the values were within the physiological range. However, a significant effect of housing system on eggshell breaking strength and eggshell weight was found. Improved eggshell quality was obtained in most periods of the laying cycle in the enriched cage systems.
Pavlík, A., Lichovníková, M., & Jelínek, P. (2009). Blood Plasma Mineral Profile and Qualitative Indicators of the Eggshell in Laying Hens in Different Housing Systems. Acta Veterinaria Brno, 78(3), 419–429. https://doi.org/10.2754/avb200978030419