Yolk Production Research Articles

The effect of CaCl2 on water migration, rheological properties, aggregation behavior and protein structure in rapidly salted separated egg yolk plasma and granules

This research investigated the effects of CaCl2 on the aggregation behavior and protein structure of egg yolk plasma and granules after fast salting. The addition of CaCl2 to the salt solution decreased T23, D [4,3] and the absolute value of the zeta potential by 6.71%, 3.66%, and 3.15%, respectively, while increasing T22 by 15.85% in egg yolk plasma. Moreover, adding CaCl2 also increased the apparent viscosity and G' value of egg yolk plasma. On the other hand, the addition of CaCl2 decreased the T22, T23, D [4,3], and absolute value of the zeta potential of egg yolk granules by 56.53%, 6.71%, 6.02%, and 34.27%, respectively. Furthermore, the addition of CaCl2 increased the number of β-turns by 51.22%, whereas it decreased the number of β-sheets by 26.55% in egg yolk plasma protein. The α-helices, β-turns, and β-sheets of egg yolk granule protein decreased by 6.58%, 3.58%, and 6.96%, respectively. Additionally, the addition of CaCl2 can increase the degree of λmax redshift in egg yolk plasma and decrease the degree of λmax redshift in egg yolk granules. Overall, the addition of CaCl2 can change the aggregation mode of proteins in egg yolk plasma and granules, improving the quality of salted egg yolk products.

Redistribution and fusion of protein-lipid assemblies within the egg yolk sphere under slight non-destructive deformation causing a change in thermal gel properties

Egg yolk production processed after separating egg white is a common method to shorten cycle, but its taste quality will change even the vitelline membrane is intact. This might be related to the slight non-destructive deformation causing redistribution and fusion of protein-lipid assemblies within the egg yolk spheres. We investigated the mechanism of the change in thermal gel properties under slight deformation. The results of microscopic structural morphology revealed that the whole boiled egg yolk (WEY) underwent a transition in protein-lipid assembly morphology within yolk spheres, which changed from local aggregation to disordered fusion in shaken boiled egg yolks (SEYs). The spectroscopic and physicochemical properties analysis demonstrated that the redistribution of protein-lipid assemblies gave rise to marked changes in water migration, texture properties, molecular interactions, and oral sensation simulation of egg yolk thermal gels. This is benefit to guide the regulation of the taste quality egg yolk products in industry.

Nondestructive testing of runny salted egg yolk based on improved ConvNeXt-T.

Salted egg yolks from salted duck eggs are widely utilized in the domestic and international food industry as both raw materials and ingredients. When salted egg yolks are not fully cured and matured, they exist in a fluid state, with a mixture of solid and liquid internally. Due to this composition, they are susceptible to deterioration during storage and usage, necessitating their detection and classification. In this study, a dataset specifically for salted egg yolks was established, and the ConvNeXt-T model, employed as the benchmark model, underwent two notable improvements. First, a lightweight location-aware circular convolution (ParC) was introduced, utilizing a ParC-block to replace a portion of the original ConvNeXt-T block. This enhancement aimed to overcome the limitations of convolution in extracting global feature information while integrating the global sensing capability of vision transformer and the localization capability of convolution. Additionally, the activation function was modified through substitution. These improvements resulted in the final model. Experimental results indicate that the enhanced model exhibits faster convergence on the custom salted egg yolk dataset compared to the baseline model. Furthermore, a significant reduction of model parameters by a factor of 4 led to a 2.167 percentage point improvement in the accuracy of the test set. The ParC-ConvNeXt-SMU-T model achieved an accuracy of 96.833% with 26.8 million parameters. Notably, the improved model demonstrates exceptional effectiveness in recognizing salted egg yolks. PRACTICAL APPLICATION: This study can be widely applied in the process of salted egg yolk production and quality inspection, which can improve the actual sorting efficiency of salted egg yolks and reduce the labor cost at the same time. It can also be used for nondestructive testing of salted egg yolks by governmental enterprises and other regulatory authorities.

Assessing the structural and foaming property changes in egg yolk proteins due to malondialdehyde: Experimental and molecular docking studies

This study evaluated the effects of varying levels of malondialdehyde (MDA) on the structural and foaming properties of the egg yolk proteins (EYPs), and the interaction between them was explored by molecular docking. The results showed that oxidative modification due to MDA increased the carbonyl content of EYPs by 4.49 times. Simultaneously, the total sulfhydryl content was reduced by 21.47%, and the solubility of EYPs was significantly decreased (p < 0.05). Continuous oxidation disorders the previously ordered structure of EYPs. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that some proteins underwent crosslinking and aggregation with increased MDA oxidation, aligning with changes in particle size and zeta-potential. Moderate oxidation (<1 mmol/L) enhanced the foaming capacity and foam stability of EYPs. Additionally, molecular docking results uncovered favorable interactions between MDA and specific EYPs, primarily through hydrogen bonding. This research offers valuable insights into managing the functional and quality changes of yolk products during processing.

Divalent metal ions under low concentration environment improved the thermal gel properties of egg yolk

To improve the thermal gel properties of egg yolk, the effect of several valence metal ions (K+, Ca2+, Mg2+ and Fe3+) with different concentrations (0-0.72%) on the rheological, gel, and structural properties of egg yolk were investigated. Results showed that monovalent and divalent ions were beneficial to the formation of uniform and dense gel network, especially with the addition of 0.72% magnesium ion, which further improved gel hardness, water holding capacity (WHC) and viscoelastic properties, the properties of egg yolk gel increased with the increase of the concentration of mono-bivalent metal ions. Adding ferric ion remarkably increased the average particle size (d4,3) and apparent viscosity of egg yolk, destroying the disulfide bonds and the hydrophobic interactions in gel. Fourier transform infrared spectroscopy (FT-IR) and fluorescence spectra analysis revealed that metal ions promoted the hydrophobic aggregation among egg yolk proteins and induced the transition of protein secondary structure from ordered to disordered. This work will provide a theoretical reference for the development of low salt and nutrient fortified egg yolk products.

The effects of sucrose/NaCl combined pickling on the textural characteristics, moisture distribution, and protein aggregation behavior of egg yolk.

Salted egg yolks have a tender, loose, gritty, and oily texture and are commonly employed as fillings in baked goods. This study investigated the formation mechanism of egg yolk gels using three different pickling methods: NaCl, sucrose, and mixed groups. The results revealed that of these pickling methods, egg yolks pickled with the mixture had the lowest moisture content (11.59% at 25°C and 10.21% at 45°C), almost no free water content, and the highest hardness (19.11 N at 25°C and 31.01 N at 45°C). Intermolecular force measurements indicated that pickling with the mixture mitigated the surface hardening effect of sucrose and facilitated protein cross-linking. Moreover, confocal laser scanning microscopy of the egg yolk gels pickled with the mixture displayed macromolecular aggregates and oil exudation, suggesting that this method partially disrupted the lipoprotein structure and notably promoted yolk protein aggregation and lipid release. Overall, egg yolks formed a dense gel via the mixed pickling method owing to the ionic concentration and dehydration effects. These findings show the impact of NaCl and sucrose in pickling egg yolks, providing a crucial foundation for developing innovative and desirable egg yolk products. PRACTICAL APPLICATION: This study introduces a novel pickling strategy that combines sucrose and NaCl for egg yolk processing. The egg yolk pickled using this method exhibited improved quality according to the evaluated textural characteristics, moisture distribution, and protein aggregation behavior. The findings may broaden the use of sucrose as a pickling agent for egg yolk processing and provide new ideas for developing and producing pickled eggs and other food products.

Unraveling the Formation Mechanism of Egg's Unique Flavor via Flavoromics and Lipidomics.

Egg products after thermal treatment possess a unique flavor and are favored by consumers. In this study, the key aroma-active compounds of egg yolk products and their formation mechanism during thermal treatment were investigated. The volatile aroma compounds in egg yolks were monitored using an electronic nose, gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry-mass spectrometry (GC-O-MS), and the lipid molecular species were explored using ultra-high-performance liquid chromatography- mass spectrometry with a Q-Exactive HF-X Orbitrap (UPLC-Q-Exactive HF-X). A total of 68 volatile compounds were identified. Boiled eggs mainly derived their flavor from hexanal, 2-pentyl-furan, 2-butanone, 3-methyl-butanal and heptane. Meanwhile, fried eggs relied mainly on 14 compounds, the most important of which were 2-ethyl-3-methyl-pyrazine, 3-ethyl-2,5-dimethyl-pyrazine, 2-ethyl-3,5-dimethyl-pyrazine, nonanal and 2,3-diethyl-5-methyl-pyrazine, providing a baked and burnt sugar flavor. A total of 201 lipid molecules, belonging to 21 lipid subclasses, were identified in egg yolks, and 13 oxidized lipids were characterized using a molecular network. Phosphoethanolamines (PEs) containing polyunsaturated fatty acids were the primary flavor precursors contributing to the development of egg yolks' flavor, participating in lipid oxidation reactions and the Maillard reaction and regulating the production of aldehydes and pyrazine compounds. This study provides reference and guidance for the development of egg yolk flavor products.

Impact of Dietary Supplementation of Cysteamine on Egg Taurine Deposition, Egg Quality, Production Performance and Ovary Development in Laying Hens.

This study aimed to examine the effect of dietary cysteamine on yolk taurine content in hens during different egg production periods. In Exp. 1, China Agricultural University-3 (CAU-3) hens at the peak stage of egg production (aged 31 wks) were used to explore the effect of diets supplemented with 0.1% cysteamine on yolk taurine content, egg quality and production performance. In Exp.2, two breeds of hens (half Hy-Line Brown and half CAU-3 hens) at the late stage of egg production (68 wks) were used to investigate the influence of diets supplemented with 0, 0.02%, 0.04%, 0.08% or 0.10% cysteamine on yolk taurine content, egg quality, production performance and ovary development. In Exp.1, diets supplemented with 0.1% cysteamine significantly increased yolk taurine content (p < 0.05) without negative influence on production performance or egg quality. In Exp.2, the highest yolk taurine content was observed when cysteamine was supplemented at 0.08% (p < 0.001). However, supplemental cysteamine linearly or quadratically decreased production performance over the first few weeks of feeding, and the effects disappeared with continued feeding (p < 0.05). In conclusion, this study indicated that cysteamine supplementation benefits yolk taurine deposition in hens at both peak and late stage of egg production, but hens at the late stage of egg production show depressed production performance and egg quality.

The dietary source of trimethylamine N-oxide and clinical outcomes: an unexpected liaison.

The profile of gut microbiota can vary according to host genetic and dietary characteristics, and be influenced by disease state and environmental stressors. The uremic dysbiosis results in a loss of biodiversity and overgrowth of microorganisms that may cause elevation of metabolic solutes such as trimethylamine N-oxide (TMAO), inducing pathogenic effects on its host. In patients with chronic kidney disease (CKD), TMAO levels are elevated because of a decreased clearance and an increased production from the uremic gut dysbiosis with a disrupted intestinal barrier and elevated enzymatic hepatic activity. Dietary precursors of TMAO are abundant in animal-derived foods such as red meat, egg yolk and other full-fat dietary products. TMAO is also found naturally in fish and certain types of seafood, with the TMAO content highly variable according to the depth of the sea where the fish is caught, as well as processing and storage. Although evidence points towards TMAO as being an important link to vascular damage and adverse cardiovascular outcomes, the evidence in CKD patients has not been consistent. In this review we discuss the potential dietary sources of TMAO and its actions on the intestinal microbiome as an explanation for the divergent results. We further highlight the potential of a healthy diet as one feasible therapeutic opportunity to prevent gut dysbiosis and reduce uremic toxin levels in patients with CKD.

Reprotoxicity induced by acute exposure to aqueous tuber extract of Peruvian Maca (Lepidium meyenii Walp.) in Caenorhabditis elegans.

Maca (Lepidium meyenii Walp.) has been used in folk medicine to treat fertility disturbances, a claim that has been evidenced in some studies. However, the clinical trials validating this use have shown paradoxical findings and then maca safety is not well known. This study investigated the effects and mechanisms by which maca affects the reproductive system using an in vivo model, the nematode Caenorhabditis elegans. Tuber maca powder, obtained from local commerce, was used to prepare the aqueous extract. Worms were acutely exposed to maca extracts (40, 120, 240, and 330 μg/μl), and 48 h after treatments, physiological and biochemical assays were conducted. Maca extract caused a significant decrease in total number of eggs and in the number of eggs per worm. These effects were associated to increased lipid peroxidation, reduced triacylglycerol levels, and also impaired vit-2 (vitellogenin) expression, besides increase in the number of apoptotic germline cells. We have found quantifiable levels of alkaloids in this maca extract, which presence could be related to this toxicity. Collectively, our data suggest that maca extract exposure causes reproductive toxicity to worms that could be, at least in part, associated to both an increase in apoptosis of germline cells and also to a decrease in vitellogenin expression, needed for egg yolk production and, consequently, successful reproduction.

Halloween genes help kissing bugs lay better eggs

Getting a ‘kiss’ on the face from an insect isn't something most people would enjoy; but you'd enjoy it even less if that insect is a kissing bug (Rhodnius prolixus), because they are transmitters of Chagas disease. While not always life-threatening, Chagas disease can lead to life-long health conditions, making it important to understand everything we can about kissing bugs. With this in mind, Samiha Benrabaa, Ian Orchard and Angela B. Lange, all from the University of Toronto, Canada, decided to investigate which genes are involved in making fully developed eggs in this species. As the team already knew that the moulting hormone, called ecdysone, is responsible for these processes in other insects such as silkworms and fruit flies, they decided to start there. First, the trio needed to identify the genes in kissing bugs responsible for producing the hormone – which is achieved by a group of genes called ‘Halloween’ genes in other species – as well as the genes responsible for the hormone receptor. Benrabaa and colleagues found five Halloween genes and two receptor genes in the insects, but then needed to see if the kissing bugs’ ovaries actually expressed these genes. They took samples from the ovaries and found that the mRNA levels for the Halloween genes and the moulting hormone receptor were highest in the part of the ovary that contains immature or developing eggs.Kissing bugs, like mosquitos, require a blood meal for the eggs to fully develop; so, the team fed the bugs before sampling mRNA from the ovaries for 6 days afterwards. Unsurprisingly, the mRNA levels of most of the Halloween genes and hormone receptors were higher after the kissing bugs ate. But just because the mRNA levels were high, didn't mean that the hormone was being produced. The team therefore next measured the amount of hormone in the bug's blood after it ate and compared this with the levels of hormone before its meal. The amount of hormone increased dramatically after a meal, suggesting that the high levels of Halloween gene mRNA were producing more moulting hormone. This raised a new question for Benrabaa: what happens to the eggs if you block some of this mRNA?To answer this, the team interfered with hormone levels by injecting the kissing bugs with a double-stranded form of RNA to knock out one of the hormone receptors or a Halloween gene called shade, and then fed the bugs. Three days later (when the yolk would normally start to develop) and 6 days later (when the eggs would usually be laid), the trio looked at the number of developing and ready-to-lay eggs in the ovaries. The injected kissing bugs produced far fewer eggs, most of which had deformities in the shape or in the outer shell. The bugs went on to lay very few of these eggs, and even fewer of these hatched, which suggested to Benrabaa that the hormone receptors and shade might interact with other genes involved in producing the egg yolk or shell. The team then tested the mRNA levels of four genes (two involved in yolk production and two involved in making the shell) in these same bugs and found that blocking mRNA for the hormone receptors or shade also caused a drop in the mRNA levels of the genes involved in egg yolk and shell production.Benrabaa explains, ‘It may be possible to use RNA-interference-based pest management using these findings’. Whether or not we could use this technology to help rid the world of Chagas disease remains to be seen, but this is certainly one step forward in the process.

The Effect of Supplementing Tea Polyphenols on Yolk Cholesterol and Production Performance of Laying Hens During the Egg-laying Period

This study aimed to investigate the effect of supplementing 300 mg/kg tea polyphenols (TP) on yolk cholesterol content and production performance of laying hens during the egg-laying period. A total of 600 Roman laying hens aged 24 weeks were randomly divided into two dietary treatment groups. The feeding experiment lasted for 48 weeks. Layers fed basal diet supplemented with 0 (control group) and 300mg/kg TP (TP group) diet, respectively. The yolk cholesterol content, laying performance, and egg quality were determined at 28, 38, 48, 58, and 68 weeks of age. The yolk cholesterol content in the TP group was significantly decreased at 28-68 weeks of age (p<0.01), compared to the control group. There was a significant increase in laying rate in the TP group at 38 weeks of age (p<0.05), compared to the control group, while no significant differences during the other laying periods were obtained (p>0.05). The FCR significantly decreased in the TP group at 38 weeks of age whereas AEW significantly increased in the TP group at 58 weeks of age (p<0.05). Similarly, the eggshell thickness and eggshell strength in the TP group significantly increased (p<0.05), compared with the control group at 38 weeks of age. The albumen height and Haugh unit significantly increased at 28 weeks of age (p<0.05). In conclusion, the results showed that the diet supplemented with 300 mg/kg TP had positive effects on production performance of layers during the egg-laying period, and could lessen yolk cholesterol content significantly at 28-68 weeks of age.

Comprehensive review on potential applications of microfluidization in food processing

Microfluidizer is one of the emerging processing technologies which has brought tremendous and desirable changes in food matrix. By generating high cavitation, shear, velocity impact and turbulent forces, microfluidizer brought structural modifications in food which led to significant improvements in physicochemical, functional, nutritional, rheological and sensory properties of food products without affecting their natural flavour. Reduction in particle size and thereby increase in surface area has brought these unique modifications. Microfluidization also improved bioavailability and bioaccessibility of bioactives by making them more exposed. Applications of microfluidizer includes stable emulsion/suspension formation, encapsulation, and nanoparticle production. It has also shown its preservation potential by inactivating enzymes and microbes thus improving food stability. The present review comprehensively discusses the working principle and effect of microfluidizer on dairy products, fruit juices, cereals, starches, egg yolk, emulsions, suspensions, and other novel products formulations. Microfluidization has opened a new channel for developing novel food ingredients non-thermally.

C. elegans feed yolk to their young in a form of primitive lactation

The nematode Caenorhabditis elegans exhibits rapid senescence that is promoted by the insulin/IGF-1 signalling (IIS) pathway via regulated processes that are poorly understood. IIS also promotes production of yolk for egg provisioning, which in post-reproductive animals continues in an apparently futile fashion, supported by destructive repurposing of intestinal biomass that contributes to senescence. Here we show that post-reproductive mothers vent yolk which can be consumed by larvae and promotes their growth. This implies that later yolk production is not futile; instead vented yolk functions similarly to milk. Moreover, yolk venting is promoted by IIS. These findings suggest that a self-destructive, lactation-like process effects resource transfer from postreproductive C. elegans mothers to offspring, in a fashion reminiscent of semelparous organisms that reproduce in a single, suicidal burst. That this process is promoted by IIS provides insights into how and why IIS shortens lifespan in C. elegans.

Desalination of duck egg white by biocoagulation to obtain peptide-ferrous chelate as iron delivery system: Preparation, characterization, and Fe2+ release evaluation in vitro.

The annual output of salted duck egg white (SDEW) is estimated to be over 1.5 million tons in China, most of which is discarded due to high salt content. This has led to serious waste and environmental impact. Therefore, we developed an eco-friendly biocoagulation separation technology by combining chitosan and sodium alginate in order to produce a novel iron-binding peptide (DPs-Fe2+) from SDEW. The structure of DPs-Fe2+ was characterized by ultraviolet-visible spectroscopy, fluorescence spectroscopy, and Fourier transform infrared spectroscopy, followed by measuring DPs-Fe2+ response in a simulated digestion/Caco-2 cell model. Results showed that chitosan and sodium alginate complex could remove 91.21% of salt from SDEW, and the protein recovery rate reached 95.50%. Characterization results indicated that DPs bonded with Fe2+ to form a soluble chelate. Moreover, Caco-2 cell monolayer model indicated that the transport rate of Fe2+ was as high as 10.02% at 0.1mg/ml concentration of digested chelates. The results demonstrate the potential application of DPs as a novel carrier for enhancing iron absorption. This research contributes to the development of an effective industrial desalination method and highlights an opportunity for recycling an otherwise discarded processing byproduct. PRACTICAL APPLICATION: Salted duck egg whites (SDEW) are the primary byproduct of salted egg yolk production, most of which is discarded due to high salt content. Hence, efficient utilization of the high-value proteins in SDEW is an urgent problem that must be resolved. Herein, we developed an effective industrial desalination method by combining chitosan and sodium alginate, which achieved excellent SDEW desalination and protein recovery. Furthermore, we produced a novel iron-binding peptide (DPs-Fe2+), which enhanced the transportation and absorption of Fe2+ in Caco-2 cell model, suggesting its potential as an iron supplement.

Pre-breeding androgen and glucocorticoid profiles in the eastern hellbender salamander (Cryptobranchus alleganiensis alleganiensis)

Seasonally breeding species exhibit cyclical changes in circulating steroid hormone profiles that correspond with changes to their reproductive behavior and ecology. Such information is critical to the conservation of imperiled and data-deficient species, such as the eastern hellbender salamander (Cryptobranchus alleganiensis alleganiensis). We determined changes in plasma testosterone (T), dihydrotestosterone (DHT), 11-ketotestosterone (11-KT), 11-ketoandrostenedione (11-KA), dehydroepiandrosterone (DHEA), cortisol, corticosterone, and progesterone (P4) during a four-month period preceding breeding in adult male and female eastern hellbenders. This pre-breeding period is characterized by increased diel movement and aggression by both sexes, follicular development and yolk production in females, and sperm production, territoriality, and nest site establishment in males. In both males and females, we observed a progressive increase in circulating T and DHT during the pre-reproductive season, both peaking in August (17 days before breeding), but concentrations of both hormones were higher in males. Conversely, 11-KT was higher in females, but did not vary significantly by date. These results suggest that T and DHT are the predominant androgens in eastern hellbenders and are likely important regulators of reproductive processes in both males and females. The detection of significant quantities of DHT and 11-KT in females is particularly interesting, considering that unlike T, neither of these androgens can be converted to estrogens. Therefore, it seems possible that aggression or some aspect of reproduction in the female eastern hellbender may be directly mediated by androgen signaling. Baseline cortisol did not vary throughout the pre-breeding period but was higher in females than males, and also became highly variable in females leading up to breeding. Progesterone, 11-KA, DHEA, and corticosterone were rarely or never detected, and thus, do not appear to be important during the pre-reproductive season. This study provides a physiological framework for future studies of hellbender reproductive biology, which could ultimately be important for their conservation.

Widespread alterations to hypothalamic-pituitary-gonadal (HPG) axis signaling underlie high temperature reproductive inhibition in the eurythermal sheepshead minnow (Cyprinodon variegatus)

Fish experiencing abnormally high or prolonged elevations in temperature can exhibit impaired reproduction, even for species adapted to warm water environments. Such high temperature inhibition of reproduction has been linked to diminished gonadal steroidogenesis, but the mechanisms whereby hypothalamic-pituitary-gonadal (HPG) axis signaling is impacted by high temperature are not fully understood. Here, we characterized differences in HPG status in adult sheepshead minnow (Cyprinodon variegatus), a eurythermal salt marsh and estuarine species of eastern North America, exposed for 14 d to temperatures of 27 °C or 37 °C. Males and females at 37 °C had lower gonadosomatic index (GSI) values compared to fish at 27 °C, and females at 37 °C had fewer spawning capable eggs and lower circulating 17β-estradiol (E2). Gene transcripts encoding gonadotropin-inhibitory hormone (gnih) and gonadotropin-releasing hormone-3 (gnrh3) were higher in relative abundance in the hypothalamus of both sexes at 37 °C. While pituitary mRNAs for the β-subunits of follicle-stimulating hormone (fshβ) and luteinizing hormone (lhβ) were lowered only in males at 37 °C, Fsh and Lh receptor mRNA levels in the gonads were at lower relative levels in both the ovary and testis of fish at 37 °C. Females at 37 °C also showed reduced ovarian mRNA levels for steroid acute regulatory protein (star), P450 side-chain cleavage enzyme (cyp11a1), 3β-hydroxysteroid dehydrogenase (3βhsd), 17β-hydroxysteroid dehydrogenase (hsd17β3), and ovarian aromatase (cyp19a1a). Females at the higher 37 °C temperature also had a lower liver expression of mRNAs encoding estrogen receptor α (esr1) and several vitellogenin and choriogenin genes, but elevated mRNA levels for hepatic sex hormone-binding globulin (shbg). Our results substantiate prior findings that exposure of fish to high temperature can inhibit gonadal steroidogenesis and oogenesis, and point to declines in reproductive performance emerging from alterations at several levels of HPG axis signaling including increased hypothalamic Gnih expression, depressed gonadal steroidogenesis, and reduced egg yolk and egg envelope protein production in the liver.

Effect of Natural and Chemical Colorant Supplementation on Performance, Egg-Quality Characteristics, Yolk Fatty-Acid Profile, and Blood Constituents in Laying Hens

Natural and chemical colorants are attracting a lot of attention as sustainable feed additives due to their effect on food color and because presentation matters to consumers. Color also is a major sensory factor that helps consumers determine food quality and its possible health benefits. For example, highly colored egg yolks can only come from healthy laying hens fed a well-balanced, nutrient-rich diet. Consumers associate an intense yolk color with healthy, nutrient-rich food. There is a growing market request for eggs with rich yolk coloring. The purpose of the current study was to evaluate the impact of natural (paprika) and chemical (carmoisine) colorant supplementation on the performance, egg-quality characteristics, yolk fatty-acid profile, and blood constituents in laying hens. A total of 240 Bovans laying hens were randomly distributed in a completely randomized design in four treatments according to four experimental diets: a control diet (without supplementation of any colorants), a control diet supplemented with 4 kg/ton paprika, a control diet supplemented with 150 g carmoisine/ton, and a control diet supplemented with a combination of 4 kg/ton paprika plus 150 g carmoisine/ton, fed from 42 to 54 weeks of age. Each treatment consisted of 10 replications with six hens. Dietary inclusion of paprika colorant improved (p &lt; 0.05) the feed-conversion ratio and egg-production rate, while final body weight, weight change, feed intake, and egg weight and mass were not affected. The degrees of egg yolk and white were increased (p &lt; 0.05) by the dietary supplements. Yolk color and shell thickness were enhanced (p &lt; 0.05) by adding paprika and/or carmoisine colorants. Supplementation of the paprika colorant alone or in combination with carmoisine increased (p &lt; 0.05) linolenic acid, oleic acid, and vitamin E concentrations in egg yolks. In contrast, egg yolk palmitic acid and liver malondialdehyde contents were decreased (p &lt; 0.05). Paprika and carmoisine colorants and their combination improved (p &lt; 0.05) blood lipid profile in treated hens. We concluded that the dietary supplementation of natural (paprika) colorants has an influential role in improving egg yolk color, production performance, and egg yolk fatty-acid profile in laying hens.

Performance of laying birds fed diets containing forage meal of Tithonia diversifolia (Hemsl A. Gray) and antibiotics

A study was conducted to evaluate the effects of dietary inclusion of the forage meal of Tithonia diversifolia with or without antibiotic on the laying performance and egg quality of birds for a period of eleven weeks. T. diversifolia is also known as wild sunflower leaf. Wild sunflower leaf meal (WSFLM) was incorporated in the diets at 75g/kg (basal diet). Streptomycin and penicillin were added to basal diet at 100 ppm each. Mixture of penicillin and streptomycin, each at 100 ppm added to the fourth diet. Control diet neither contained WSFLM nor antibiotic. The results of weekly performance at first week of the study, showed that there were significant (P&lt;0.01) increases for egg production, hen day production and feed efficiency for birds fed diets containing WSFLM, while egg weight and feed intake were not affected. Haugh Unit (P &lt;0.05) and egg breadth (P &lt;0.01) 8th week, whereas food consumption at second (P &lt;0.05), fourth and fifth weeks (P &lt;0. 01) were all significantly influenced by the dietary treatments. Yellow pigmentation of egg yolks was significantly (P &lt;0.01) enhanced by WSFLM throughout 77 days. The summary of the data at the end of the study indicated that WSFLM significantly (P &lt;0.01) enhanced egg. Weight, egg production, Egg yolk and hen day production (P &lt; 0.05). Control birds and those fed basal diets with antibiotic significantly (P &lt;0.05) retained protein and ether extract than those fed basal diet. Supplementation of basal diet with either penicillin or streptomycin positively affected the egg production and egg weight at 77th day, whereas the mixture of the two antibiotics adversely affected the performance of the birds. It is therefore advisable that WSFLM at 75 g kg-1 in combination with either penicillin or streptomycin at 100ppm may be included in the diet of laying birds

The Effect of Supplementing Tea Polyphenols in Diet of Laying Hens on Yolk Cholesterol Content and Production Performance

ABSTRACT This study was conducted to evaluate the influence of supplementing tea polyphenols (TP) in diet of laying hens on yolk cholesterol content and production performance. A total of 1800 Lohmann laying hens aged 48 weeks were randomly allocated to 6 groups. Each group consisted of 6 replicates with 50 layers. The feeding experiment was 4 weeks including one-week acclimatization. Layers fed basal diet supplemented with 0, 150, 200, 250, 300 and 350 mg TP/kg diet, respectively. The results showed that average daily feed intake (ADFI), feed conversion ratio (FCR), average egg weight (AEW), laying rate and the indicators of egg quality were not significantly affected by the diet supplemented with 300 mg/kg TP (p>0.05). However, yolk cholesterol content decreased by increasing TP concentration (p<0.01), with 18.06% reduction in layers fed diet supplemented with 300 mg TP/kg. Also, the diet supplemented with 300 mg/kg TP significantly decreased plasma triglyceride (TG), total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C) level (p<0.05). The activity of serum glutathione peroxidase (GSH-Px) was enhanced by increasing TP concentration, while the content of serum methane dicarboxylic aldehyde (MDA) was decreased by increasing TP concentration. The highest activity of GSH-Px and the lowest serum MDA content were both determined in 300 mg/kg TP group (p<0.01). In conclusion, this study suggests that the addition of 300 mg TP/kg basal diet had no negative effect on the production performance laying hens, yet decreased the egg yolk cholesterol content and enhanced the antioxidant capacity of laying hens at the same time.