Trace Mineral Sources and Rosemary Oil in the Diet of Brown Laying Hens: Egg Quality and Lipid Stability

ABSTRACT Two experiments were carried out to evaluate the effects of rosemary oil (RO) and trace mineral sources (MS) on the internal quality and lipid stability of brown layer eggs. The treatments consisted of diets supplemented with two trace mineral sources (inorganic or organic) and three levels (0, 100, or 200 mg kg-1) of rosemary oil (RO), and three egg storage times. Eggs were stored at a controlled temperature (CT; 25.0ºC) in Experiment I and under refrigeration (RT; 5.0ºC) in Experiment II. The following parameters were analyzed on days 0 (fresh), 15 and 30 of storage: malonaldehyde level (MDA), egg weight (EW), Haugh unit (HU), yolk index (YI), albumen and yolk pH, raw yolk color (RYC), and egg weight loss. Data were analyzed according to completely randomized design in a 2x3x3 factorial arrangement (MS x RO x storage time). In Experiment I, there was an interaction between treatments for EW, HU and ALBp. Dietary OTM inclusion improved the results for all analyzed variables. The addition of 200 mg kg-1 RO reduced MDA and increased HU, YI and RYC. In experiment II, 200 mg kg-1 of RO in the diet improved HU. The internal quality of eggs stored both at CT and under RT is adversely affected by increasing storage periods, but this effect can be minimized by the dietary supplementation of OTM and 200 mg kg-1 rosemary oil. The lipid stability of eggs stored at CT improves with the supplementation of OTM and 200 mg kg-1 rosemary oil, but not of eggs stored under refrigeration.摘要 本研究开展两项试验，以评估迷迭香精油（rosemary oil, RO）与微量矿物质源（trace mineral sources, MS）对褐壳产蛋鸡鸡蛋内部品质及脂质稳定性的影响。试验处理设置为：日粮添加两种微量矿物质源（无机型或有机型），并设置3个迷迭香精油添加水平（0、100、200 mg·kg⁻¹），同时设置3个鸡蛋储藏时长梯度。试验I中鸡蛋于恒温环境（CT；25.0℃）储藏，试验II中鸡蛋于冷藏环境（RT；5.0℃）储藏。 在储藏第0天（鲜蛋）、第15天及第30天，对以下指标进行测定：丙二醛含量（malonaldehyde level, MDA）、蛋重（egg weight, EW）、哈氏单位（Haugh unit, HU）、蛋黄指数（yolk index, YI）、蛋白与蛋黄pH值、生蛋黄色泽（raw yolk color, RYC）以及蛋重损失。试验数据采用2×3×3因子设计的完全随机试验设计（MS×RO×储藏时长）进行统计分析。 试验I结果显示，蛋重、哈氏单位与蛋白pH值存在处理间交互效应。日粮添加有机微量矿物质（organic trace minerals, OTM）可提升所有测定指标的表现。日粮中添加200 mg·kg⁻¹的迷迭香精油可降低丙二醛含量，并提升哈氏单位、蛋黄指数与生蛋黄色泽。 试验II中，日粮添加200 mg·kg⁻¹的迷迭香精油可提升哈氏单位。无论于恒温环境还是冷藏环境储藏，鸡蛋的内部品质均会随储藏时长延长而出现劣变，但通过日粮添加有机微量矿物质与200 mg·kg⁻¹迷迭香精油，可有效缓解这一负面影响。恒温储藏条件下的鸡蛋脂质稳定性可通过日粮添加有机微量矿物质与200 mg·kg⁻¹迷迭香精油得到改善，但该改善效果在冷藏储藏的鸡蛋中并不显著。