Fatty acid profile and oxidative stability of egg yolks from hens under different production systems

Abstract

<jats:p>AbstractThis study was carried out to compare the egg quality, fatty acid (FA) profiles, and oxidative stability of yolks from hens maintained in cages and fed a conventional diet (CON), those fed a conventional diet with free access to outdoor grassy area (5 m2/hens) under free-range conditions (FR), and those fed an organic diet and free access to outdoor grassy area (10 m2/hens) under in organic system (ORG). Heavier eggs were produced by CON, while percentages of yolk and eggshell were greater in eggs of FR and ORG hens. The FR and ORG hens produced eggs that contained significantly more monounsaturated fatty acids (MUFAs) but less polyunsaturated fatty acids (PUFAs) than CON hens. Eggs from FR and ORG hens had a lower concentration of PUFA n-6 because of less C18:2 n-6 (linoleic acid) and a higher percentage of PUFA n-3 (eicosapentaenoic acid). Consequently, the ratio of PUFA n-6 to n-3 for eggs from FR and ORG hens was healthier for consumers compared with CON. However, eggs from the ORG hens had a similar FA profile to those from the FR hens. No significant differences were noted in hypocholesterolaemic (HI), atherogenic (AI) and thrombogenic indexes. Antioxidant concentration was greatest in eggs from ORG hens (retinol-14.32 μg/g and α-tocopherol-98.7 μg/g/yolk). Thus, the oxidative stability of eggs measured after storage at 4°Cfor 15 or 30 days was improved. The best eggs in terms of nutritional value were from the ORG system in which hens lived in their natural environment.&#x0D; Keywords: antioxidants, conventional production, egg quality, free range production, malonaldehyde, organic production</jats:p>

Laying Performance, Egg Quality Characteristics, and Egg Yolk Fatty Acids Profile in Layer Hens Housed with Free Access to Chicory- and/or White Clover-Vegetated or Non-Vegetated Areas

“…The Haugh unit, a measure of egg protein quality based on the albumin height, and egg yolk colour, an important commercial characteristic, are both important properties of egg quality, along with other parameters such as eggshell thickness and strength. In contrast to results reported previously [4,15,17,35], the HI of hens did not have a significant effect on the Haugh unit and egg yolk colour. This discrepancy among the studies might be due to differences in the housing type (deep or floor litter, cage, or enrich cage), vegetation type (grass, legume, other forbs, or their mixture), the range utilization percentage, the environmental conditions, and the age and strain of hens used [14,17,35,36].…”

“…These observations may explain why the PCA grouped the FAs of the yolk differently and the mutual correlations between FA profiles of the egg yolk modified by the FAs ingested via the HI. Mierlit , ă [15] noted that the FA profile of egg yolk was characterized by a relatively low SFA and high MUFA and PUFA proportions, as reported herein. Moreover, findings relating to the FA profiles of the yolk were similar to previous reports [15,22,39] in which the yolk FA contents were maximized when the relevant FA was higher in the diet, reflecting a higher concentration of FAs in fresh herbage.…”

“…The HI might have changed the mineral content [15] and the calcium to available phosphorus ratio of the diet [3,32] and reduced intestinal calcium uptake because feed ingredients from plant sources are inadequate in meeting the requirements for calcium and phosphorus [33]. Therefore, the decreased eggshell thickness in the vegetated area groups, a major concern of the egg industry, could be associated with the consumed forage.…”

“…As such, feeding forage or pasture intake in outdoor-based systems (conventional free-range systems or organic systems) for laying hens has gained tremendous attention in the poultry research field, as highlighted by certain reviews [2][3][4][5][6][7]. A considerable body of research has shown that in general, these systems delivered low egg production and a high feed conversion ratio (FCR), but they delivered high-quality and heavier eggs compared with conventional systems [1,[8][9][10][11][12][13][14][15][16]. These findings resulted from reduced feed intake and diluted diets due to forage or pasture intake versus increased energy requirements of laying hens [3,17].…”

Żywność w XXI wieku – jakość, składniki, zdrowie

“…[2018], Hidalgo i in. [2013], jak również Mierliță [2020] wykazali, że wraz z ekstensyfikacją systemu chowu następuje wzrost zawartości kwasów jednonienasyconych (ang. monounsaturated fatty acids, MUFA) w żółtkach jaj.…”