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Background: Although the importance of phosphorylation in the function of proteins is known, investigation of the protein phosphorylation of duck egg yolk (DEY) is still very limited. This study aimed to conduct a detailed phosphoproteomic study of DEY using immobilized metal affinity chromatography and ultra-high liquid chromatography tandem mass spectrometry., Results: A total of 253 phosphorylation sites assigned to 66 phosphoproteins were identified in DEY, of which VTG-1, VTG-2, and fibrinogen alpha chain were found to be the highly phosphorylated proteins in DEY. The biological functions of the identified phosphoproteins were illuminated through gene ontology analysis, which showed that they were mainly involved in binding, catalytic, immune response, and metabolic activity. S-X-E and S-X-S were found to be the most conserved serine motifs of phosphorylation in DEY. The comparison of DEY phosphoproteins with those of chicken egg yolk (CEY) revealed that differences mostly involved molecular functions and biological processes. The comparison also revealed a higher phosphorylation level in DEY proteins., Conclusion: The higher phosphorylation level in DEY proteins than that in CEY proteins are supposed to help enhance duck growth performance and biological activities (e.g. antibacterial and antioxidant ability) for better adapting the humid environment the duck lived. © 2021 Society of Chemical Industry., (© 2021 Society of Chemical Industry.)

Background: While eggs are a low-cost source of protein, rich in macro- and micronutrients, the association of egg intake and cardiovascular disease (CVD) remains controversial. This study investigated the effect of egg consumption on CVD parameters. Eggs were boiled, separated into four fractions (whole egg, 50% yolk-reduced whole egg, egg yolk and egg white) and then freeze-dried. The different egg fractions or distilled water (control) were orally gavaged to adult male Wistar rats at 1 g kg -1 rat body weight, each day for 8 weeks, following which basal blood pressure, heart rate, complete blood cell count, blood biochemistry, body fat and liver cell lipid accumulation were determined. The vascular functions of isolated thoracic aorta were studied using classical pharmacological techniques., Results: In comparison to the control group, none of the egg fractions affected body weight, food intake, plasma glucose or lipid profile. The yolk group experienced increased plasma alkaline phosphatase and creatinine levels, while egg white caused decreased plasma cholesterol and blood urea nitrogen. Whole egg and egg yolk increased blood pressure and mean hemoglobin concentration and the yolk increased liver lipid accumulation. Egg white decreased the white blood cell count and body fat lipids. No changes were found in basal heart rate or vascular functions in any of the groups., Conclusions: Consumption of whole egg or egg yolk at the dosage given caused hypertension, with impairment of liver and kidney functions following the intake of yolk alone. However, egg white is beneficial for the cardiovascular system as it decreased plasma cholesterol and body fat accumulation. © 2020 Society of Chemical Industry., (© 2020 Society of Chemical Industry.)

Background: The research deals with the addition of microalgae Schizochytrium limacinum as an alternative to fish oil in a feed-mixture for laying-hens and its effect on the deposition of n-3 polyunsaturated fatty acids (n-3-PUFAs) [α-linoleic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)] in the lipids of egg yolks. In the study, 240 Tetra SL laying hens housed in enriched cages were used, divided into six groups, each in five repetitions. Groups E1, E3 and E5 were given 0.5%, 1.0% and 1.5% microalgae and groups E2, E4 and E6 were given feed mixtures with 0.5%, 1.0% and 1.5% fish oil. The mixtures were modified on the basis of 17% of the crude protein and 11.7 MJ ME kg -1 ., Results: The results showed satisfactory disposal of n-3 PUFA in egg yolks of laying-hens fed mixtures with the addition of either fish oil or microalgae. Eggs of E1, E3 and E5 groups contained in 100 g: 321.07 mg, 361.60 mg and 399.34 mg n-3 PUFA, respectively (P < 0.001). Eggs of E2, E4 and E6 groups contained in 100 g: 346.25 mg, 346.17 mg and 369.02 mg n-3 PUFA, respectively (P < 0.001). By increasing the content of fish oil or microalgae in feed-mixtures for laying hens, the ratio of n-6/n-3 PUFA in egg yolk lipids (P < 0.001) was decreased., Conclusion: Our results justified the usage of the microalgae Schizochytrium limacinum in the enrichment of table eggs with n-3 fatty acids as an alternative feed to fish oil. © 2019 Society of Chemical Industry., (© 2019 Society of Chemical Industry.)

Background: Egg yolks contain large amounts of cholesterol and are suspected to be harmful after long-term consumption. In this experiment, 63 rats were used to evaluate the effect of egg white (EW) and egg yolk (EY) supplementation on serum lipids and brain cognition. The feeding time lasted 4 weeks after a 1-week acclimation., Results: Body weight was significantly higher in rats fed 132.0 g kg -1 EW and significantly lower when fed 40 g kg -1 EY (P < 0.05). Total cholesterol and low-density lipoprotein increased in rats fed 72.0 g kg -1 EW compared with rats from NC and EY groups (P < 0.05). High-density lipoprotein (HDL) was higher in rats fed 40 g kg -1 EY and decreased when fed 72.0 g kg -1 EW (P < 0.05). Rats fed a diet with EY exhibited abundant neurons in the CA1 hippocampus and complete subcellular structures. Rats fed 132 g kg -1 EW exhibited shrunken cells and swollen mitochondria. Brain-derived neurotrophic factor had constitutively low expression among groups, while tyrosine kinase B (TrkB) exhibited higher expression levels in rats fed a diet containing EY compared with other groups (P < 0.05)., Conclusion: EY consumption reduced body weight and increased HDL levels. Diet containing EY could improve cognition through enhanced trkB expression. © 2019 Society of Chemical Industry., (© 2019 Society of Chemical Industry.)

Background: Lutein is a plant pigment very important for eye health in humans. Its bioavailability in humans is better from egg yolk than from dietary supplements. The aim of this research was to determine the influence of lutein (marigold extract powder) supplemented to laying hens' feed rich in omega-3 fatty acids on the content of lutein, fatty acid profile in egg yolks and yolk color. The diets that contained 5% of oils as a source of omega-3 fatty acids were supplemented with 0, 1 and 2 g kg -1 of marigold powder., Results: The best enrichment of eggs with lutein was achieved by supplementing 2 g marigold kg -1 of feed. Yolk color was significantly intensified (P < 0.001) by supplementing 1 g marigold kg -1 of feed. The content of total saturated fatty acids, monounsaturated fatty acids and n-6 polyunsaturated fatty acids (PUFA) remained unchanged, whereas the content of total n-3 PUFA (P = 0.017) and docosahexaenoic acid (P < 0.001) was higher in the group with 2 g marigold kg -1 of feed. This group also had the most favorable ratio of n-6:n-3 PUFA., Conclusion: Results of this research showed that addition of marigold powder to laying hens' feed significantly increased egg lutein content and yolk color, and altered the fatty acid profile in yolk. Eggs with increased lutein content and a favorable profile of fatty acids are a good source of these ingredients in human nutrition. © 2018 Society of Chemical Industry., (© 2018 Society of Chemical Industry.)

Background: Polyunsaturated fatty acids (PUFA) are crucial components of egg yolk and particularly prone to oxidative damage, generating losses of nutrients for embryonic development and influencing the quality of eggs for human consumption. The aim of this study was to evaluate whether dietary thymol (a natural antioxidant) is related to changes in quail egg yolk total (T), triglyceride (TG) and phospholipid (PL) fatty acid composition at different stages of embryo development. Thus female Japanese quail (100 days of age) were assigned to one of two dietary treatments (12 individuals each): CON (basal diet) or THY (0.0016 mol thymol day -1 per bird). After 2 weeks of supplementation, eggs were incubated and samples were obtained at 0, 4 and 16 days of embryonic development., Results: In 0 day THY eggs, α-linolenic acid and n-3 PUFA in T and TG, docosahexaenoic acid and PUFA in T and arachidonic acid in TG were increased, while saturated fatty acids (SFA) in T were reduced. From 4 days on, PUFA, n-3 PUFA and SFA from T and TG in THY eggs were found to be similar to those of CON eggs. The changes in PL throughout incubation were similar in both dietary treatments., Conclusion: Thymol would provide the embryo with PUFA for synthesis/deposition in membranes and/or assign to supply energy. Additionally, thymol supplementation would be advisable for the production of healthier table eggs. © 2017 Society of Chemical Industry., (© 2017 Society of Chemical Industry.)

Background: High-energy diets of laying hens may improve roductive performance, although some negative effects may also appear with respect to egg quality and physiological parameters. Curcuma longa rhizome powder (CRP) has beneficial effects on health indices of the birds through antioxidant and antimicrobial properties, especially when the birds experience nutritional stress., Results: Increasing dietary CRP enhanced egg quality by improving eggshell thickness and hardness but decreasing yolk cholesterol content (P < 0.05). The best feed conversion ratio was obtained in birds fed high-apparent metabolizable energy (AME) diets supplemented with 2.0 g kg -1 CRP (P < 0.05). Although increasing dietary AME elevated the serum concentration of triglycerides (P < 0.05) and enzymatic activities of alanine aminotransferase and aspartate aminotransferase (P < 0.05), dietary inclusion of CRP alleviates the blood levels of these enzymes (P < 0.01). Low level of dietary CRP boosted the immune responses to Newcastle virus (P < 0.01) and sheep red blood cells (P < 0.05) antigens but decreased the heterophil to lymphocyte ratio (P < 0.05). Inclusion of at least 2.0 g kg -1 CRP in the diet of laying decreased Escherichia coli enumerations in the ileal content (P < 0.01) and improved villus height, crypt depth and goblet cell numbers (P < 0.05)., Conclusion: An improvement in the productive performance of laying hens fed high-energy diets might be associated with decreasing health indices and product quality, which could potentially be amended by nutritional modifications such as incorporating medicinal herbs in the feed. © 2016 Society of Chemical Industry., (© 2016 Society of Chemical Industry.)

Background: Dietary lutein and its food sources have gained great attention due to its health-promoting effects on humans, especially for certain eye diseases. However, relative bioavailability (RBV) of lutein among lutein-rich feed ingredients that lead to lutein-enriched egg production has not been determined. Thus, the RBV of lutein in corn distillers dried grains with solubles (DDGS) as compared to lutein in corn gluten meal (CGM) was evaluated based on lutein retention in egg yolk., Results: Increasing inclusion levels of DDGS or CGM in diets increased (linear, P < 0.01) Roche colour score and lutein concentrations of egg yolk without affecting laying performance. Multiple regression analysis revealed that the bioavailability of lutein in DDGS was less (P < 0.05) than that of lutein in CGM, with the RBV of lutein in DDGS being 61.6% when the bioavailability of lutein in CGM was assumed to be 100% for lutein retention in egg yolk., Conclusion: The results of the present experiment indicate that the DDGS can be a potential ingredient for laying hens to improve egg yolk colour and lutein concentrations of egg yolk although lutein in DDGS is less bioavailable than lutein in CGM. © 2015 Society of Chemical Industry., (© 2015 Society of Chemical Industry.)

Background: Strontium is currently prescribed for patients with osteoporosis to increase bone density and reduce bone fractures but its relevance in animal nutrition is obscure. In order to investigate the effect of supplemental strontium and vitamin D3 on performance, egg quality and skeletal integrity in poultry a total of 108 laying hens, 99 weeks of age, were fed three levels of strontium (0, 500, 1000 mg kg(-1) ) and two levels of vitamin D3 (2500, 5,000 iu kg(-1)) over a 12-week period., Results: There was an improvement (P < 0.05) in egg production and feed conversion efficiency with strontium at 500 mg kg(-1) and a significant increase in egg weight in those hens fed additional vitamin D3 . Supplemental strontium increased phosphorus, sodium and strontium retention in birds fed 2500 iu D3 kg(-1) but reduced phosphorus, sodium and strontium retention in birds fed 5000 iu D3 kg(-1), resulting in an interaction (P < 0.01) between strontium and vitamin D3 . Addition of 5000 iu D3 kg(-1) increased egg weight (P < 0.05); predominantly by increased albumen content (P < 0.05), whereas strontium supplementation reduced egg weight (P < 0.001). Similarly, 5000 iu kg(-1) D3 increased apparent metabolizable energy (P < 0.05); in contrast, strontium supplementation reduced (P < 0.05) apparent metabolizable energy., Conclusion: The addition of 500 mg kg(-1) strontium significantly improved egg production and feed efficiency; however, further investigation needs to be undertaken to refine the optimum level of strontium required to maximize hen performance. The interrelationship between strontium and vitamin D3 requires further exploratory study., (© 2014 Society of Chemical Industry.)

Background: Gracilariopsis persica (Gp) is one of the most abundant red algae distributed in the Persian Gulf, containing various bioactive components with hypolipedimic, hypoglycemic and antioxidant properties. Therefore using laying quails as a model we aimed to investigate the effect of dietary Gp on body weight, feed conversion, estradiol, progesterone, calcium and lipid levels in serum, as well as the high-density:low-density lipoprotein (HDL:LDL) ratio. Yolk cholesterol and yolk lipid oxidation were also evaluated. To accomplish this, diets containing 0, 10, 30 and 50 g kg(-1) Gp were fed to 5-week-old laying quails for 12 weeks., Results: Our data revealed that Gp had no effect on body weight, feed conversion, triglycerides and estradiol levels of serum. Dietary Gp decreased the serum and yolk cholesterol in a dose-dependent manner. In addition, the sera progesterone and calcium levels and HDL:LDL ratios were increased by feeding diets containing 50 g kg(-1) Gp. Our results relating to yolk lipid oxidation showed that malondialdehyde content was decreased in Gp-fed laying quails., Conclusions: The results of the present study demonstrate that not only serum and egg yolk cholesterol levels, but also susceptibility of yolk lipids to oxidation, can be decreased by feeding Gp to laying quails., (© 2014 Society of Chemical Industry.)

Background: The main component in tocotrienols (T3) from barley (Hordeum vulgare L.) is α-T3, the vitamer with the highest bioavailability, while palm oil T3 is particularly rich in γ-T3. Unlike tocopherols, T3 are known for their cholesterogenesis-inhibiting, neuroprotective and anticarcinogenic properties. In this study the oral bioavailabilities of T3 from barley oil (3.98 mg day⁻¹) and T3 from palm oil (3.36 mg day⁻¹) in nanoemulsified formulations (NE) and self-emulsifying systems (SES) were compared using hen's eggs as a bioindicator. In addition, the transfer efficiencies of barley oil T3 and palm oil T3 into egg yolk were compared, as well as their effects on egg cholesterol levels., Results: Nanoemulsification led to T3 levels (132.9 µg per egg) higher than with non-emulsified barley oil (112.8 µg per egg) and barley oil SES (116.7 µg per egg) owing to the high proportions of α-T3 (99-117 µg per egg), which has a particularly high transfer efficiency (4.32-6.75%). T3 contents of eggs from hens fed barley oil supplements (112-132 µg per egg) were significantly higher than those of eggs from hens fed palm oil supplements (70-78 µg per egg). Addition of barley and palm oils to laying hen feed decreased egg yolk cholesterol by 4 and 6% respectively., Conclusion: Results from this animal study may help to establish T3 from barley as a dietary supplement and to develop nutritionally improved hen's eggs., (© 2013 Society of Chemical Industry.)

Background: This study attempts to compare two possibilities of enhancing the colour of egg yolk. One of them is based on the ecological rearing of laying hens on natural green grass whereas the other uses a feeding dose supplemented with natural pigments in laying hens reared in individual cages. Is it possible to distinguish these two technologies using yolk colour determination in the CIELAB system?, Results: Yolk colour parameters such as L*, a*, and b* in the group of grazed hens are significantly different (α = 0.001) from those observed in hens reared in cages. The yolk colour shows a darker, redder and more yellow colour. The greatest difference was seen in the red colour parameter, a*, that increased more than twice. Visually, this means a shift towards a more orange colour. Compared to grazing in the meadow (ΔE* = 13.257), the addition of artificial pigments in the feed resulted in a more significant increase in the parameter ΔE* (CIE total colour difference), with the greatest value of ΔE* being observed with the use of both pigments (ΔE* = 24.265)., Conclusion: Grazing increases the parameter a* whereas the values of the parameter C*(ab) remain relatively low. The parameter ΔE* is significantly lower in the case of grazing as compared to the supplementation of the feed with pigments. However, colourity parameters cannot be used as a specific standard to identify a particular grazing technology as their values vary during the laying period., (Copyright © 2011 Society of Chemical Industry.)

Background: The health benefits of n-3 fatty acids have led to much research on manipulating the fatty acid composition of animal-derived foods. In this study, two experiments were conducted to investigate the interaction of dietary fatty acids on egg yolk fatty acid concentrations. In experiment I, 32 dietary treatments with three replicates of three birds each were fed for 35 days. Diets were prepared by mixing one type of fish oil with four vegetable oils in different proportions. In experiment II, three different types and two levels of fish oil in combination with two vegetable oils were tested under the same conditions as in experiment I., Results: In experiment I the results showed that the egg yolk saturated (SFA) and monounsaturated (MUFA) fatty acid concentration was determined by the dietary SFA, MUFA and 18:2n-6 content. The egg 18:2n-6 concentration was mainly explained by the dietary inclusion of 18:2n-6 and negatively by the dietary MUFA content. The egg C18:3n-3, C20:5n-3 and C22:6n-3 concentration is almost exclusively determined by their direct supply from the diet. The egg 20:4n-6 concentration was inversely proportional to the long-chain n-3 polyunsaturated fatty acid content of the diet. The results of experiment II showed that the egg yolk C20:5n-3 and C22:6n-3 concentration was determined by both the level of dietary fish oil (1 or 2%) and the C20:5n-3/C22:6n-3 ratio in the fish oil., Conclusion: The results of this study demonstrated that the direct dietary supply of fatty acids is the most important factor determining the egg yolk fatty acid composition, in particular for the n-3 fatty acids. The interaction effect from other dietary fatty acids was in general small., (Copyright © 2011 Society of Chemical Industry.)

Background: Supplying egg-laying hens with different forage materials may influence egg production and quality. The aim of this study was to examine the short-term effects of standard feed plus 70 g day(-1) per hen of three coloured carrot varieties (orange, yellow and purple) as forage material in comparison with a standard feed control on egg production, egg yolk colour and deposition of carotenoids in the yolk., Results: Carrot supplementation reduced feed intakes significantly, but not on a dry matter basis. Orange carrot treatment significantly reduced egg mass production, whereas yellow and purple carrot treatments did not differ from the control. Egg and yolk weights of all carrot-supplemented treatments were significantly lower than those of the control, but yolk percentages were similar. Yolk redness increased significantly in the order control < yellow < orange < purple. A similar trend was seen for yolk yellowness, but yellow and orange carrots reached the same level. Yolk colour and carotenoid contents correlated positively and significantly. In particular, purple carrot treatment increased the yolk content of lutein (>1.5-fold) and beta-carotene (>100-fold) compared with the control., Conclusion: Supplementing the feed of egg-laying hens with coloured carrots efficiently increased yolk colour parameters and carotenoid contents, which gives opportunities for improved nutritional value of eggs from forage material-supplemented hens.