Yolk Content Research Articles

Doxycycline depletion and residues in eggs after oral administration to laying hens

The depletion of doxycycline (DC) residues in eggs was determined after oral drug administration by drinking water to laying hens. The antibiotic was supplied to birds for 5 consecutive days and the eggs were collected during medication and 18 days after withdrawal. DC residues were determined by LC-MS/MS. DC was isolated from eggs with a solution of 0.02 M of oxalic acid (pH 4), 0.1 M Na2EDTA and acetonitrile. The limit of detection (LOD) and limit of quantification (LOQ) of the method were 2 and 5 µg kg–1, respectively. Analyses were performed on whole egg, egg white and yolk separately. DC was detectable 24 h after the beginning of administration. The concentration of antibiotic increased daily, resulting in the highest DC concentration in whole eggs at the first day of the withdrawal period. Thirteen days after withdrawal, the content of DC in whole eggs was below the LOQ of the method. However, some differences were found in the depletion curve of DC between egg white and yolk. Residues of DC in egg white were much higher during treatment and 1 day after withdrawal, but later the concentration in egg white decreased fairly rapidly and a higher DC content in egg yolk was observed. The depletion period was shorter for egg white than for yolk, and DC was detected in the egg white until 12 days after withdrawal and 2 days more in egg yolk than in white. DC reached a peak faster in egg white, but the residues were detectable for longer period in the yolk.

Single-cell mass spectrometry reveals small molecules that affect cell fates in the 16-cell embryo

Spatial and temporal changes in molecular expression are essential to embryonic development, and their characterization is critical to understand mechanisms by which cells acquire different phenotypes. Although technological advances have made it possible to quantify expression of large molecules during embryogenesis, little information is available on metabolites, the ultimate indicator of physiological activity of the cell. Here, we demonstrate that single-cell capillary electrophoresis-electrospray ionization mass spectrometry is able to test whether differential expression of the genome translates to the domain of metabolites between single embryonic cells. Dissection of three different cell types with distinct tissue fates from 16-cell embryos of the South African clawed frog (Xenopus laevis) and microextraction of their metabolomes enabled the identification of 40 metabolites that anchored interconnected central metabolic networks. Relative quantitation revealed that several metabolites were differentially active between the cell types in the wild-type, unperturbed embryos. Altering postfertilization cytoplasmic movements that perturb dorsal development confirmed that these three cells have characteristic small-molecular activity already at cleavage stages as a result of cell type and not differences in pigmentation, yolk content, cell size, or position in the embryo. Changing the metabolite concentration caused changes in cell movements at gastrulation that also altered the tissue fates of these cells, demonstrating that the metabolome affects cell phenotypes in the embryo.

Cryopreservation of Sambar deer semen in Thailand.

Little is known of the different freezing and thawing techniques for post-thaw survival of spermatozoa in Sambar deer. So, this study determined the effect of seminal plasma, egg yolk and glycerol extenders and their concentrations, plus cooling, freezing, and thawing protocols on the post-thaw quality of their semen. Semen samples were collected by electro-ejaculation from four Thai Sambar deer stags (Cervus unicolor equinus). As evaluated by post-thaw progressive motility and acrosome integrity removal of seminal plasma was beneficial; Tris-egg yolk was the most efficient extender; a 20% egg yolk concentration was better than the 0%, 10%, or 30%; and a 3% glycerol concentration was better than 5%, 7%, or 9%. Using the optimum dilution techniques, semen was loaded in 0.5 ml plastic straws. Cooling times from ambient temperature to 5°C in 3 hr resulted in higher post-thaw progressive motility and acrosome integrity than 1, 2, or 4 hr. Suspending the straws 4 cm above the surface for 15 min before plunging into liquid nitrogen was better than suspending at 2 or 6 cm. For thawing frozen semen, an intermediate thawing (50°C, 8 sec) protocol was more effective than the slower (37°C, 10 sec) or faster (70°C, 5 sec) thawing rates. Timed insemination following estrus synchronization of 10 hinds resulted in six confirmed pregnancies at 60 days. Five hinds delivered live fawns. This study provides an effective approach for semen cryopreservation and artificial insemination (AI), which should be valuable to scientists for genetics and reproductive management of Sambar deer in developing countries.

Techno-functional characterization of salad dressing emulsions supplemented with pea, lentil and chickpea flours.

Salad dressings supplemented with pulse flours are novel products. A three-factor face-centered central composite design (CCD) was used to determine the effect of pulse flour concentration (3.5%, 7%, 10.5% w/w), egg yolk concentration (3%, 5%, 7% w/w) and oil concentration (20%, 35%, 50% w/w) on the rheological and color characteristics of salad dressings supplemented with pulse flours. The consistency coefficient m, plateau modulus G(N)(0), recoverable strain Q(t) and color values were all affected by the concentrations of pulse flours used. Scanning electron microscopy showed that dressings with lower oil and egg yolk contents had a less densely packed network compared with dressings with higher oil and egg yolk contents. Sensory results were most promising for salad dressings supplemented with the whole green lentil, yellow pea with low flour content, and chickpea with high oil content. This study should be useful for designing novel types of salad dressings to meet market requirements as well as helping to increase pulse consumption.

The influence of year, laying date, egg fertility and incubation, individual hen, hen age and mass and clutch size on maternal immunoglobulin Y concentration in captive Steller's and spectacled eider egg yolk

Steller's eiders and spectacled eiders are sea duck species whose populations have declined significantly and infectious diseases could influence offspring survival. Therefore, the maternal transfer of immunoglobulin Y (IgY) into yolk was investigated in captive Steller's and spectacled eiders during the 2007–2013 breeding seasons. This project had two objectives: establish baseline IgY levels in Steller's and spectacled eider yolk under controlled captive conditions and evaluate the effect of year, laying date, egg fertility, egg incubation duration, individual hen, hen age and mass, and laying order to determine which variables influenced IgY levels. Average IgY concentrations were 0.03–0.48 mg ml−1 in Steller's eider yolk and 0.10–0.51 mg ml−1 in spectacled eider yolk. The year and individual hen influenced IgY concentration in Steller's and spectacled eider yolk. The laying date was negatively correlated with egg IgY levels for most Steller's eider hens, but laying order was positively correlated with egg IgY concentration for spectacled eiders.

THE MODULATION OF PERFORMANCE, CHOLESTEROL CONTENT AND IMMUNE RESPONSE INDUCED BY SACCHAROMYCES CEREVISIAE IN LAYING HENS

This study was conducted to evaluate the effect of Saccharomyces cerevisiae supplementation of a commercial layer diet on the laying performance, blood lipid profile, liver and yolk cholesterol content, and immune response during 8-week period. A total of 180 Hy-line Brown laying hens of 40 wk of age were allocated to 4 dietary treatments, where every 45 hens were divided into three replicates. The basal diet was supplemented with Saccharomyces cerevisiae at the levels of 0.0, 0.2, 0.4, and 0.6%. Results showed that the highest egg number and egg weight were observed with 0.6% Saccharomyces cerevisiae supplement. Supplementing diets with Saccharomyces cerevisiae at all levels (0.2, 0.4, and 0.6%) significantly (P˂0.05) increased egg mass, antibody production, cell-mediated immune response, and reduced feed consumption, plasma cholesterol, LDL-cholesterol levels and liver cholesterol concentration. Furthermore, hens fed diets supplemented with 0.4 and 0.6% Saccharomyces cerevisiae showed significant enhancement of feed conversion ratio, an increase of plasma HDL-cholesterol and a reduction of both yolk cholesterol concentration and Heterophil:lymphocyte (H/L) ratio. In conclusion, Saccharomyces cerevisiae could be used to enhance production performance and immune response, and control cholesterol content of plasma, yolk and liver.

Increase in lutein and zeaxanthin content in the eggs of hens fed marigold flower extract

Marigold flower extract (MFE), a natural source of xanthophylls, was added to the diets of hens at different concentrations (0, 150, 250, and 350 mg/kg of diet) to determine the effects of MFE on hen per - formance, physical characteristics of egg quality, and carotenoid content of the egg yolk of hens housed in enriched cages. Additionally, the highest dose of MFE (350 mg/kg) was tested under commercial poultry condi - tions and compared with a feed mixture with added synthetic carotenoids and a control diet without synthetic carotenoids. The highest hen-day egg production ( P = 0.005) and egg mass production ( P = 0.010) was found in hens fed a diet supplemented with MFE at 150 mg/kg. The performance characteristics, however, were not influenced by MFE under commercial conditions. When the dose of MFE was increased, increased values were observed for DSM Yolk Colour Fan ( P < 0.001), redness ( < 0.001), yellowness ( P < 0.001), ratio of redness and yellowness ( P < 0.001), and decreased for lightness ( P = 0.036). In the commercial study, the synthetic carotenoids decreased the value of yellowness ( P < 0.001) compared with the control group. The lutein and zeaxanthin content in yolk increased by approximately 11.5 and 5.9 mg/kg dry matter, respectively, after the MFE addition of 350 mg/kg. Supplementation with synthetic carotenoids significantly ( P < 0.001) decreased the α-tocopherol content in egg yolk. In conclusion, MFE is a suitable natural alternative for increasing the xanthophyll contents in eggs compared with the commercially used synthetic carotenoids.

Microencapsulation of bull spermatozoa: Its viability in alginate-egg yolk media

Microencapsulation of spermatozoa is a process to entrap a number of spermatozoa in microcapsule. Alginate, as a natural polymer polysaccharide is commonly used in cell microencapsulation. Tris Yolk Citrate buffer is a good buffer for spermatozoa dilution, therefore this experiment aimed to determine optimal concentration of alginate and egg yolk to sperm quality in bull spermatozoa microencapsulation. Concentration of egg yolk and alginate in media of encapsulation were determined in applications of sperm microencapsulation. Four bulls were used as semen source and only semen with good quality were used in this study. Poolled semen was diluted using the medium to get final concentration 100 x 10 6 cell/ ml. The first study was conducted to determine the effect of concentration of alginate (0, 1, and 1.5%) on viability of spermatozoa. The second study to determine the effect of alginate concentration, egg yolk and its interaction was done by comparing two levels of alginate (1 and 1.5%) with four levels of egg yolk (5, 10, 15 and 20%). Viability of spermatozoa, motility (M), live spermatozoa (L) and Intact Apical Ridge (IAR) were observed at 0, 1, 2 and 3 h incubation at room temperature. Results indicated that alginate concentration increased the osmolality and viscosity but did not affect pH of the medium. The osmolality and viscosity of medium were 275, 325, 425 and 1.12, 26.62, 47.98 for concentration of alginate 0, 1 and 1.5% respectively. Percentage of motility is significantly lower (P<0.05) in alginate medium than those of control, and 1.5% alginate could produce more uniform beads. Concentration of alginate, egg yolk and its interaction did not significantly affect viability of sperm. It is concluded that the combination of 1.5% alginate with 5, 10, 15 or 20% egg yolk can be used as media for sperm encapsulation.

Effect of dietary marine microalgae (schizochytrium) powder on egg production, blood lipid profiles, egg quality, and Fatty Acid composition of egg yolk in layers.

Two hundred and sixteen Institut de Sélection Animale (ISA) brown layers (40 wks of age) were studied for 6 wks to examine the effect of microalgae powder (MAP) on egg production, egg quality, blood lipid profile, and fatty acid concentration of egg yolk. Dietary treatments were as follows: i) CON (basal diet), ii) 0.5% MAP (CON+0.5% Schizochytrium powder), and iii) 1.0% MAP (CON+1.0% Schizochytrium powder). From 44 to 46 wks, egg production was higher in 1.0% MAP treatment than in control treatment (linear, p = 0.034); however, there was no difference on the egg production from 40 to 43 wks (p>0.05). Serum triglyceride and total cholesterol were significantly reduced in the groups fed with MAP, compared to those in groups fed with control diets (Quadratic, p = 0.034 and p = 0.039, respectively). Inclusion of 0.5% MAP in the diet of layers improved egg yolk color, compared with hens fed with basal diet at 46 wks (quadratic, p = 0.044). Eggshell thickness was linearly increased in MAP-fed treatments at 46th wk (p<0.05). Concentration of yolk docosahexaenoic acid (DHA; C22:6n-3) was increased in treatment groups fed with MAP (linear, p<0.05). The n-6 fatty acids, n-6/n-3 fatty acid, and unsaturated fatty acid/saturated fatty acid were decreased in treatment groups fed with MAP (linear, p<0.05). These results suggest that MAP improved the egg production and egg quality, and may affect serum lipid metabolites in the layers. In addition, MAP increases yolk DHA levels, and deceases n-6/n-3 fatty acid ratio.

Effect of Dietary Nano-Selenium Supplementation on Selenium Content and Oxidative Stability in Table Eggs and Productive Performance of Laying Hens

The main target of this study was to evaluate the effect of dietary Nano-Selenium (Nano-Se) supplementation on selenium (Se) content and oxidative stability in table eggs and productive performance of laying hens. One hundred and eighty silver Montazah laying hens (Egyptian local developed strain) aged 32 weeks were housed in individual cages in a semi-open house. Birds were divided randomly into six treatments and fed a basal diet (vitamins and minerals mixture without Se). The experiment involved a 2 x 3 factorial arrangement, 2 Se sources (sodium selenite and Nano-Se) and 3 levels of each source (0.10, 0.25 and 0.40 ppm). Feed and water were provided ad libitum throughout the experimental period (three month). The prepared 80 nm Se nano particles were synthesized by chemical reduction method and characterized by Transmission Electron Microscope, X-ray diffraction and spectrophotometry. Different Se levels of sodium selenite or Nano-Se did not affect egg weight, feed intake and most of egg quality. Egg production percentage and egg mass increased and the feed conversion ratio significantly improved, by adding Nano-Se in layer diets. Increasing Se level from 0.10 up to 0.40 ppm either sodium selenite or Nano- Se significantly increasing Se content in eggs and the highest concentration was recorded with high level (0.40 ppm) of Nano-Se. Moreover, increased glutathione peroxides (GSH-Px) activity, with reduction of Malondialdehyde (MDA) content in yolk of stored eggs at room temperature for 15 days. Adding 0.25 ppm of Nano-Se recorded the lower saturated to unsaturated fatty acids ratio thus improved the fatty acid profile and oxidative stability during storage. Nano-Se significantly reduced total lipids, total cholesterol and increased HDL-cholesterol to total cholesterol ratio in maternal hens (plasma and yolk). The main histopathological findings of livers for all treatments were fatty liver with focal aggregation of inflammatory cells. While the spleen showed congestion of blood vessels. Conclusions: It can be concluded that, supplemental layer diets with 0.25 ppm of Nano-Se was effective in improving the productive performance and GSH-Px activity of layer and producing Se enriched egg which could supply 50% (35 µg) of the human Se Recommended Daily Allowances. This give a hand in solving the problem of Se deficiency in food for human.

Sperm–egg penetration assay assessment of the contraceptive effects of glycerol and egg yolk in rooster sperm diluents

Glycerol (GLY) and egg yolk (EY) are good cryoprotectants of avian and mammalian sperm, but in birds, they strongly inhibit the eventual fertilization of ova. Using the sperm penetration (SP-holes) assay and fertility trials, the present study investigates (1) the possible mechanism by which this contraceptive effect occurs in chickens and (2) the maximum concentrations of GLY and EY tolerated by fresh rooster sperm. Seventy Black-Barred Andaluza hens (five per treatment) were inseminated four times (twice per week) with 0.1 mL of fresh semen from roosters of the same breed diluted 1:1 (v:v) with Lake and Ravie medium containing different concentrations of GLY or EY. No adverse effects on acrosome integrity, sperm motility, or viability were seen with any concentration of GLY or EY. The number of SP-holes on perivitelline layer samples taken from above the germinal disc became progressively lower at GLY concentrations of 1.5% or greater (P > 0.05). No holes caused by sperms were seen in unfertilized eggs. The corresponding fertility results showed similar reductions when the GLY concentration was 1.5% or greater. No changes in the number of SP-holes were seen with increasing EY concentrations (0%–7.5%), nor were any differences in fertility observed, except for a reduction when 15% EY was used. The results therefore reveal that GLY affects the transit of sperms through the oviduct in their attempt to reach the infundibulum area, limiting their access to the ovum perivitelline layer. Egg yolk had no such effect, nor did it influence acrosome reaction capacity; its mechanism of contraceptive action therefore remains unknown. The maximum GLY and EY concentrations tolerated by the rooster sperm were 0.75% and 7.5%, respectively.

Increased yolk progesterone interferes with prenatal auditory learning and elevates emotional reactivity in bobwhite quail (Colinus virginianus) chicks.

Avian eggs contain maternally derived hormones, including testosterone and progesterone. Little is currently known about the effects of these hormones on early behavioral development. We assessed the effects of elevated levels of progesterone levels on prenatal perceptual learning and postnatal emotional reactivity in Northern bobwhite quail. Prior to incubation, eggs received an injection of either progesterone (P) or oil vehicle (V). In P eggs, levels of progesterone were elevated two standard deviations above the mean based on ELISA analysis of progesterone yolk concentrations from a previous study. A third group of eggs served as controls and received no injection (C). Chicks hatched from P eggs displayed elevated levels of emotional reactivity compared to V and C chicks in a tonic immobility task and a hole-in-the-wall emergence task. Chicks from P eggs also failed to demonstrate a preference for a familiarized bobwhite maternal call that had been presented prenatally. In contrast, the V and C chicks demonstrated a significant preference for the familiarized maternal call following hatching, indicating prenatal auditory learning. Our results are consistent with previous findings from precocial birds demonstrating that hormones of maternal origin can influence prenatal perceptual learning as well as emotional reactivity in the period following hatching..

Implication of milling methods, thermal treatment, and particle size of feed in layers on mineral digestibility and retention of minerals in egg contents

Feed production with different milling methods, thermal treatment, and particle size may influence mineral digestibility and retention in eggs. The present study investigated the impact of roller (R) and hammer (H) mills, mash (M) and expandate (E) with fine (F) and coarse (C) particle sizes, on apparent ileal absorption (AIA) and apparent total digestibility (ATD) and retention of calcium, phosphorus, magnesium, zinc, manganese, copper and iron in yolk, albumen, and shell. A total of 384 hens (Lohmann Brown), 19 weeks old, were assigned using a randomized design with a 2 × 2 × 2 factorial arrangement. Eight experimental diets were offered ad libitum during the whole experimental period and one week before for diet adaption. The AIA of magnesium, zinc, copper, and iron was higher in treatment R in comparison with treatment H (P < 0.01, P ≤ 0.03, P < 0.01 and P < 0.01, respectively). The AIA of magnesium was higher in treatment M than treatment E (P < 0.01). The AIA of magnesium was higher in treatment C in comparison with treatment F (P ≤ 0.05) due to particle size. The ATD of copper and iron was higher in treatment R than treatment H (P < 0.01 and P ≤ 0.03, respectively). The ATD was higher for phosphorus and lower for iron in treatment F than treatment C (P ≤ 0.05 and P ≤ 0.02. respectively). The copper concentration in yolk and albumen was higher in treatment C than treatment F (P < 0.01 and P ≤ 0.03, respectively). Besides a few overall interactions, the AIA and ATD of copper and manganese were lower in H+M group than R+M group (P ≤ 0.05). The ATD of iron was higher in the M+C group compared to the M+F group (P < 0.01), whereas the albumen zinc concentration was higher in the E+C group than E+F group (P < 0.01). In conclusion, the feed produced by hammer mill had negative effects on AIA and ATD for trace elements in particular, but mineral concentrations in egg contents were mostly comparable for all treatments. Therefore, milling methods, thermal treatment, and particle sizes used in the present study can be used for layer feed formulation without negatively affecting egg quality.

Deposition and depletion of maduramicin residues in eggs after oral administration to laying hens determined by LC-MS

The coccidiostat maduramicin has been approved as a feed additive for chickens and turkeys, although it is prohibited for use in laying hens. In the present study, laying hens were divided into three groups and fed for 14 days with medicated feed containing maduramicin, at three different concentrations: 50, 100 and 500 µg kg−1. Eggs were collected during treatment and for 26 days after the end of feeding with medicated feed. Maduramicin residues were found exclusively in egg yolk, with the highest concentration in egg yolk of 459 µg kg−1 for the highest dose. The maximum concentration of maduramicin in whole egg was 16.6 µg kg−1 for the group receiving feed containing the maximum permitted level of maduramicin in feed (50 µg kg−1). The half-life of elimination of maduramicin, calculated for post-treatment days 1–10, was 6.5 days. Twelve days after drug administration, the concentration of the maduramicin in egg yolk for Group 3 (fed with 500 µg kg−1 maduramicin) still exceeded 20 µg kg−1, while the concentrations for Groups 1 and 2 were 1.2 and 2.7 µg kg−1, respectively.

Evaluation of conductivity and moisture content of eggs during storage by using transformer method

This study was aimed to establish a detecting system based on transformer method to evaluate moisture content and conductivity of egg albumen and yolks during storage. Results showed that the decrease in impedance of albumen and yolk resulted in the increase in the secondary terminal voltage during the eggs’ storage. Terminal voltage positively correlated with electric conductivity, regardless of frequency. The highest linear coefficient of determination (0.9955) between moisture content of yolk and terminal voltage at 50Hz was observed. Exponential correlations emerged between the eggs’ conductivity and terminal voltage, with highest coefficient of determination (R2=0.8311 for albumen, R2=0.9772 for yolk) at 200Hz and 400Hz, respectively. The correlations obtained in frequencies ranging from 50 to 400Hz at 10V laid the foundation for a method of evaluating moisture content and conductivity in albumen and yolks. Results facilitate an alternative application of the technique for rapid evaluation of the quality indices of liquid food products.

Comparison of the Nutritional Value of Egg Yolk and Egg Albumin from Domestic Chicken, Guinea Fowl and Hybrid Chicken

The present study was conducted to compare the nutritional and physical quality of egg yolk and egg white of birds from three different genotypes (domestic chicken, hybrid chicken and guinea fowl). The egg yolk and white from each of the bird were separated and analyzed for proximate, vitamins and minerals using standard analytical methods. The eggs of the 3 bird species showed similar conical shape, however, weight of whole egg, egg white and yolk of hybrid chicken was much higher than that of domestic and guinea fowl. The moisture (60.45+0.14%) and vitamin C (121.50+0.14mg/100g) contents of egg yolk were significantly higher in hybrid chicken than in domestic chicken and guinea fowl while the protein (5.47+0.88%), ash (1.32+0.03%) and vitamin C (68.50+0.70mg/100g) contents of egg white was higher in hybrid chicken than domestic chicken and guinea fowl. However, moisture contents (87.45+0.71%) of egg white from guinea fowl was Original Research Article Bashir et al.; AJEA, 6(5): 310-316, 2015; Article no.AJEA.2015.089 311 significantly (p<0.05) higher than hybrid chicken. All elements considered in this study had higher concentrations (mg/100g) in egg yolk than white except for Na whose concentrations were higher in egg white than yolk. The concentration of K (321.50+7.62 and 119.50+2.6.2), Fe (12.45+0.09 and 4.45+0.0.8) and Ca 2+ (26.60+0.63 and 9.23+0.22) for egg yolk and white respectively was significantly (p<0.05) higher in guinea fowl than domestic and hybrid chicken. However, Na contents in hybrid chicken (850.00+22.40 and 975.00+09.00) for egg yolk and white respectively was significantly (p<0.05) higher than that of guinea fowl and domestic chicken. It is concluded that egg yolk and white of hybrid chicken were riches in moisture, protein, ash, vitamin C and sodium than guinea fowl and domestic chicken. While egg yolk and white of guinea fowl were rich in K + , Fe and Ca than the eggs of domestic and hybrid chicken.

Composition of some botanical mixtures as potential feed additives for laying hens

The aim of this study was to assess the nutritional quality of four botanical mixtures (AFC): AFC 1 (containing red corn, pumpkin pulp and marigold), AFC 2 (containing alfalfa meal, pumpkin pulp and marigold), AFC 3 (containing kale, alfalfa meal, marigold and spinach leaves), AFC 4 (containing buckthorn, red corn, pumpkin pulp and marigold), in terms of proximate analysis (crude protein, crude fat, crude fiber, ash), amino acid (AA) profile, vitamin E concentration and lutein and zeaxanthin content, in order to determine the potential of AFCs as feed additives in laying hens nutrition. The crude protein content for the analysed botanical mixtures ranged between 9.07-18.18% DM, and crude fiber between 10.41-30.83% DM. The amino acid profile of the mixture AFC 4 revealed a content of limiting essential amino acids required for laying hens: lysine 5.719% CP, methionine 1.058% CP and threonine 4.415% CP. The highest content of lutein and zeaxanthin was found in the mixture AFC 4 (66.659 mg/100 g), which also had the highest amount of vitamin E (640.93 mg/kg). With regard to safety of the botanical mixtures, lead and cadmium concentrations were determined. Concentration of lead ranged from 0.28-0.75 µg/g DM and 0.06-0.09 µg/g DM for concentration of cadmium, which was within the legislation of maximal limits of EU regulations. It can be concluded that the botanical mixture AFC 4 had the highest concentration of lutein, zeaxanthin and vitamin E, with an adequate content of essential amino acids. Furthermore, all four botanical mixtures had high amounts of xantophylls and should be tested in laying hens trials in order to establish their effects on lutein and zeaxanthin concentration in egg yolk.

Estimation of dietary selenium requirement for Chinese egg-laying ducks

The purpose of this study was to estimate the selenium (Se) requirement of egg-laying ducks based on daily egg production and the selenoprotein glutathione peroxidase (Gpx). Five-hundred and forty laying ducks were divided into six treatments, each containing six replicates of 15 ducks. The birds were caged individually and received a Se-deficient basal diet (0.04 mg/kg) or diets supplemented with 0.08, 0.16, 0.24, 0.32, 0.40 mg/kg Se (as sodium selenite) for 6 months. The experiment consisted of two periods: an early-laying period of 2 months and the peak-laying period of 4 months. Egg production and feed intake were recorded daily. At the end of the experiment, blood samples were drawn for determination of Gpx activity in plasma (Gpx3) and in erythrocytes (Gpx1). Hepatic Gpx1 activity and relative expression of Gpx1 mRNA were also determined. Eggs (n = 6) were sampled for quality determination and Se content at the end of the experiment. The activities of plasma Gpx3, erythrocyte Gpx1 and liver Gpx1 increased in a quadratic manner (P &lt; 0.001) with increasing supplemental Se. The mRNA abundance of hepatic Gpx1 increased linearly (P &lt; 0.001) with dietary Se supplementation. Egg shell thickness was significantly reduced in the ducks fed 0.44 mg Se/kg (P &lt; 0.05), indicating that higher dietary Se tends to compromise egg shell quality. Yolk and albumen contents of Se increased linearly (P &lt; 0.0001) with dietary Se supplementation. Using quadratic broken line models, the Se requirement for daily egg production was 0.18 mg/kg for early-laying ducks and 0.24 mg/kg for peak-laying ducks; for optimal function of Gpx (peak-laying ducks), it was 0.37 mg Se/kg.

Modeling PCB transfer into hen eggs: influence of physiological characteristics of the animal.

Laying hens are likely to be exposed to a wide range of persistent organic pollutants (POPs), including polychlorinated biphenyls (PCBs). To improve the safety of poultry farming systems in terms of POPs, the present research focused on assessing the impact of physiological characteristics of the hen on the transfer of ingested PCBs to eggs. Modeling was used as a research tool to explore the impact of some physiological characteristics on the transfer of PCBs in the laying hen. The mathematical model simulates the dynamics of the size of the lipid compartments in the animal and the frequency of laying, with the PCB concentrations in egg yolk and adipose tissue being model outputs. Simulations were run to assess effects of animal characteristics on the transfer of PCBs to eggs. Laying rate proportionally influenced the PCB level of eggs and adipose tissue at steady state. Body fat diluted absorbed PCBs in the absence of laying and significantly influenced the decontamination rate of tissues during depuration after an exposure period. Application of the present model to actual exposure cases highlights its value in improving the support of risk management in livestock farming.

Effects of Manganese and Iron Organic Sources in Layer Diets on Nutritional Quality of Eggs

Organic trace minerals present a higher bioavailability and stability, therefore lower rates of inclusion in feed will be needed to meet the poultry nutritional requirements which will lead to a lower environmental output. The purpose of this study was to determine the effect of total replacement of the inorganic Mn and Fe salts by organic forms of these elements on nutritional quality of eggs and on apparent absorption coefficients. A study was conducted on 192 laying hens, housed in cages (2 birds/cage), divided into 3 groups (C, E 1 , E 2 ). All groups received a similar diet (17.96% CP and 2724.31 kcal/kg ME). Diet E 1 used the same level of Mn and Fe as diet C, but in chelated form (71.9 mg Mn/kg and 60 mg Fe/kg). Compared to C, diet E 2 had the same level of Fe (inorganic source) but the Mn concentration was 200 mg/kg (organic source). Every two weeks egg samples were collected randomly (18 eggs/group). During the study, all droppings were daily collected in order to form average weekly samples/cage, from which Mn, Fe was determined by FAAS. The replacement of the inorganic Mn and Fe salts by chelates of these minerals in layers diets didn’t affect their performances. The analytical results showed an improvement of nutritional quality of eggs in terms of significant (P≤0.05) increasing of Mn concentration in egg yolk for E 2 (1.84±0.28 mg/kg) compare to C (1.46±0.16 mg/kg) and E 1 (1.59±0.30 mg/kg) but without any statistically assured improvement of Fe concentrations. The apparent absorption coefficients of Fe and Mn were higher for E 2 compare to the other two groups (E 1 , C). A possible explanation of these results could be the existent interactions between the trace elements found in animal organism, a high concentration of Mn being able to influence positively the absorption of Fe in organism. The chelate source of trace minerals can be a way of obtaining Mn enrichment eggs but only using amounts of Mn above conventional rate.