Context In Australia and many other countries, free-range eggs can be sold at significantly higher prices than cage eggs. Mislabelling cage eggs as free-range eggs and vice versa has been documented, and has a significant impact on consumer trust and egg consumption. The development of methods to identify eggs produced from different production systems is necessary to satisfy consumer demand. Aims The objective of this study was to determine whether eggshell mineral composition could be used as a way to differentiate eggs originating from each production system. Our hypothesis was that birds with access to soil would have higher levels of trace minerals in shells. Methods Eggs were randomly collected from six commercial caged and six commercial free-range flocks in Australia. Twelve eggshell samples from each flock were analysed for mineral composition (Ca, P, Mg, Na, Al, B, Cu, Mn, Fe, K, S and Zn) by using inductively coupled plasma-optical emission spectrometry. Key results The results showed that free-range eggshells contained significantly higher contents of macro-minerals (P, Mg and Na) but lower contents of micro-minerals (Cu, Fe, K, S and Mn) than the cage eggshells (P < 0.05). For all minerals measured, a high variability was noted within and between production systems. Conclusions Analysis of eggshell mineral composition may not be effective for determining the origin of eggs. Implications Systematic studies of the bird’s environment, including analysis of mineral composition in diets, pastures, soil and drinking water are required for comprehensive evaluation of the influences of production systems of laying hens on mineral composition of eggs and eggshells.

中文翻译：

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电感耦合等离子发射光谱法比较笼养鸡蛋与散养鸡蛋蛋壳矿物成分

背景 在澳大利亚和许多其他国家，散养鸡蛋的售价远高于笼养鸡蛋。已经记录了将笼养鸡蛋错误标记为自由放养鸡蛋，反之亦然，这对消费者信任和鸡蛋消费产生了重大影响。为了满足消费者的需求，有必要开发识别来自不同生产系统的鸡蛋的方法。目的 本研究的目的是确定蛋壳矿物质成分是否可以用作区分来自每个生产系统的鸡蛋的方法。我们的假设是，能够接触土壤的鸟类的贝壳中的微量矿物质含量会更高。方法 从澳大利亚的 6 个商业笼养和 6 个商业散养鸡群中随机收集鸡蛋。通过使用电感耦合等离子体-光学发射光谱法分析了来自每个鸡群的 12 个蛋壳样品的矿物质成分（Ca、P、Mg、Na、Al、B、Cu、Mn、Fe、K、S 和 Zn）。主要结果 结果表明，与笼养蛋壳相比，散养蛋壳的宏观矿物质（P、Mg 和 Na）含量显着更高，但微量矿物质（Cu、Fe、K、S 和 Mn）含量较低（P < 0.05）。对于所有测量的矿物，在生产系统内和生产系统之间注意到高度可变性。结论 蛋壳矿物质成分分析可能无法有效确定鸡蛋的来源。影响 对鸟类环境的系统研究，包括分析饮食、牧场、