Research Note: Improvement of eggshell strength and intensity of brown eggshell color by dietary magnesium and δ-aminolevulinic acid supplementation in laying hens

The objective of the current experiment was to investigate the effect of dietary magnesium (Mg) and δ-aminolevulinic acid (ALA) supplementation on productive performance and egg quality in laying hens. The present experiment was performed using a completely randomized design with 2 × 2 factorial arrangements including 2 levels of supplemental Mg (0 and 0.12%) and ALA (0 and 0.25%) in diets. A total of 192 43-wk-old Hy-Line Brown laying hens were allotted to 1 of 4 dietary treatments with 6 replicates. Each replicate consisted of 4 consecutive cages with 2 hens per cage. Treatment diets were fed to hens for 6 wk. Results indicated that dietary Mg supplementation improved (P < 0.01) eggshell strength but decreased (P < 0.05) eggshell color score, regardless of dietary ALA supplementation. However, the decreased eggshell color by dietary Mg supplementation was relieved by dietary ALA supplementation, which led to a significant interaction (P < 0.05). Likewise, an interaction (P < 0.05) was also observed for eggshell lightness (L*) because dietary ALA supplementation decreased eggshell L* values only when Mg was supplemented to diets. In conclusion, dietary Mg supplementation improves eggshell strength but decreases the intensity of brown eggshell color in laying hens. However, this negative effect of dietary Mg supplementation on eggshell color is likely ameliorated by dietary ALA supplementation.