M.B.  Chang, C.H.  Kim, I.K.  Paik, D.Y.  Kil, 
    Effects of Dietary Magnesium Concentrations on Performance and Eggshell Quality of Laying Hens,
    Journal of Animal and Veterinary Advances,
    Volume 12,Issue 1,
    2013,
    Pages 104-107,
    ISSN 1680-5593,
    javaa.2013.104.107,
    (https://makhillpublications.co/view-article.php?doi=javaa.2013.104.107)
    Abstract: The objective of this experiment was to investigate the effect 
  of dietary Magnesium (Mg) concentrations on productive performance and eggshell 
  quality of laying hens. A total of 800 Hy-Line Brown laying hens (46 weeks old) 
  were randomly allotted to 1 of 5 dietary treatments with 4 replicates per treatment. 
  A commercial-type basal diet (1.7 g kg<SUP>-1</SUP> Mg) was prepared and 4 additional 
  diets were formulated to contain 2.3, 3.0, 3.5 or 4.2 g kg<SUP>-1</SUP> Mg in 
  diets by adding 1.0, 2.0, 3.0 or 4.0 g of MgO (600 g kg<SUP>-1</SUP> Mg) to 
  the basal diet. The diets were fed to hens as <I>ad libitum</I> basis for 6 
  weeks. Results indicated that increasing concentrations of Mg in diets increased 
  Mg concentrations in eggshells (linear and quadratic, p&lt;0.05). Increasing 
  concentrations of Mg in diets increased eggshell strength (quadratic, p&lt;0.05) 
  and eggshell thickness (linear, p&lt;0.05) but decreased Hunter a* values for 
  eggshell (linear, p&lt;0.01). Hen-day egg production, feed intake, feed conversion 
  ratio, egg weight and Haugh unit were not affected by Mg concentrations in diets. 
  In conclusion, feeding diets containing increasing concentrations of Mg up to 
  4.2 g kg<SUP>-1</SUP> to laying hens improves eggshell strength and eggshell 
  thickness but has no effects on productive performance of laying hens.
    Keywords: Eggshell quality;laying hens;magnesium;productive performance;effect of dietary