Untargeted UHPLC-TOF/MS Lipidomic Analysis for the Investigation of Egg Yolks after Xylanase Supplementation of the Diet of Laying Hens.

Xylanase supplementation of diets is used to enhance nutrient digestibility in monogastrics which lack necessary enzymes for non-starch polysaccharide degradation. The effects of enzymatic treatment in the nutritional value of the feed are typically not comprehensively studied. Though the fundamental effects of xylanase on performance are well studied, limited data is available on the complex interactions between xylanase supplementation and hen physiology; therefore, the aim of this study was to develop a new, simple UPLC-TOF/MS lipidomics method for the analysis of hen egg yolks after supplementation with different amounts of xylanase. Sample preparation for the extraction of lipids was optimized and different sample preparation modes and solvent mixtures were tested. Optimal results for the extraction of total lipids were obtained by using the solvent mixture MTBE: MeOH (5:1, v/v). Multivariate statistical analysis of the signals of hundreds of lipids in positive and negative ionisation modes highlighted differences in several egg yolk lipid species-classes. Four lipid species-classes, phosphatidylcholines (PC and PC O), phosphatidylethanolamines (PE and PE O), phosphatidylinositols (PI), and fatty acids (FA), were among those contributing to the separation of the experimental groups (control-treated) in negative ionisation mode. In positive ionisation mode, principal beneficial lipid compounds such as phosphatidylcholines (PC and PC O), phosphatidylethanolamines (PE and PE O), triacylglycerols (TG), diacylglycerols (DG), and ceramides (Cer) were found to be increased in treated groups. Overall, supplementation of laying hens' diets with xylanase significantly changed the lipid profile of egg yolks compared to the control diet. The association between the lipid profiles of egg yolks and hens' diets, as well as the underlying mechanisms, require further investigation. These findings are of practical significance for the food industry.

Effects of Dietary Supplementation of Salvia officinalis L. in Organic Laying Hens on Egg Quality, Yolk Oxidative Stability and Eggshell Microbiological Counts.

Aromatic plants of Labiatae family are used in poultry diets because of their antimicrobial and antioxidant activity. The notion is that hens raised in organic systems face several health and environmental challenges. Hence, the objective here was to assess hens' performances and the quality of their eggs in such systems following a dietary supplementation of Salvia officinalis L. in powder form. The experiments were conducted over two successive years (1 and 2). They lasted 16 weeks each and involved 198 laying hens aged 40 weeks old randomly assigned to three groups: Con (control diet), Sal-0.5%, and Sal-1.0% (diets supplemented with Salvia officinalis L. at 0.5% or 1.0%, respectively). The malondialdehyde (MDA) levels in egg yolks in year 2 were lower in both Sal-0.5% and Sal-1.0% compared to the Con (p < 0.05). The total number of Enterobacteriaceae in eggshells were lower in Sal-1.0% compared to the Con (p < 0.05) in both years. The results suggest that a dietary supplementation of Salvia officinalis L. at 1.0% improves the antioxidant status and reduces the microbial load of eggs produced in organic systems.