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.