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.

中文翻译：

---

不同水平日粮镁对蛋壳质量和蛋鸡生产性能的影响。

本研究旨在研究不同水平的日粮镁 (Mg) 对蛋壳质量和蛋鸡生产性能的影响。使用四种日粮处理，包括含有 3.19 g/kg Mg 的商业型基础日粮和补充 2、4 或 6 g/kg 氧化镁 (MgO) 以提供 4.03、4.87 或 5.71 g/kg Mg 的三种额外日粮在完全随机的设计中。总共 120 只 35 周龄的 Bovans White 蛋鸡接受了 8 周的日粮处理。结果表明，日粮中镁浓度的增加显着增加了母鸡日产蛋量和采食量（P < 0.05）。日粮镁补充剂对蛋重、饲料转化率和平均日增重没有影响。蛋壳重量、厚度、日粮中添加镁可显着提高体重和强度（P < 0.05）。日粮处理显着增加了蛋黄重量（P < 0.05），但降低了蛋黄颜色（P < 0.05）。不同饮食处理的蛋白重量、哈夫单位、蛋黄形状和蛋形指数相似。通过在日粮中加入镁，蛋壳镁含量（g/kg 干物质）显着增加。总之，本研究的结果表明，在日粮中添加高达 5.71 g/kg 的镁可改善蛋壳质量和蛋鸡的生产性能。通过在日粮中加入镁，蛋壳镁含量（g/kg 干物质）显着增加。总之，本研究的结果表明，在日粮中添加高达 5.71 g/kg 的镁可改善蛋壳质量和蛋鸡的生产性能。通过在日粮中加入镁，蛋壳镁含量（g/kg 干物质）显着增加。总之，本研究的结果表明，在日粮中添加高达 5.71 g/kg 的镁可改善蛋壳质量和蛋鸡的生产性能。