This study aimed to investigate the effects of different levels of dietary magnesium (Mg) on eggshell quality and laying hen's performance. Four dietary treatments including a commercial-type basal diet containing 3.19 g/kg Mg and three additional diets supplemented with 2, 4, or 6 g/kg magnesium oxide (MgO) to provide 4.03, 4.87, or 5.71 g/kg Mg were used in a completely randomized design. A total of 120 Bovans White layers at the age of 35 weeks were fed with dietary treatments for 8 weeks. Results indicated that increasing concentrations of Mg in the diets significantly increased hen-day egg production and feed intake (P < 0.05). Dietary Mg supplementation had no effect on egg weight, feed conversion ratio, and average daily weight gain. Eggshell weight, thickness, and strength were significantly increased by adding Mg to the diets (P < 0.05). Dietary treatments significantly increased yolk weight (P < 0.05) but decreased yolk color (P < 0.05). Albumen weight, Haugh unit, yolk shape, and egg shape index were similar among the dietary treatments. Eggshell Mg content (g/kg of dry matter) was significantly increased by the inclusion of Mg in the diets. In conclusion, the results of this study indicated that supplementation of Mg up to 5.71 g/kg diet improved eggshell quality and laying hen's performance.
Keywords: Egg internal quality; Eggshell quality; Laying hens; Magnesium; Performance.