Eggshell Color Research Articles

Transcriptomic analysis of the liver in aged laying hens with different intensity of brown eggshell color.

ObjectiveEggshell color is an important indicator of egg quality for consumers, especially for brown eggs. Various factors related to laying hens and their environment affect brown eggshell coloration. However, there have been no studies investigating hepatic functions of laying hens with variable intensity of brown eggshell color. Therefore, this study was aimed to identify potential factors affecting brown eggshell coloration in aged laying hens at the hepatic transcriptomic level.MethodsFive hundred 92-wk-old Hy-line Brown laying hens were screened to select laying hens with different intensity of brown eggshell color based on eggshell color fans. Based on eggshell color scores, hens with dark brown eggshells (DBE; eggshell color fan score = 14.8) and hens with light brown eggshells (LBE; eggshell color fan score = 9.7) were finally selected for the liver sampling. We performed RNA-seq analysis using the liver samples through the paired-end sequencing libraries. Differentially expressed genes (DEGs) profiling was carried out to identify their biological meaning by bioinformatics.ResultsA total of 290 DEGs were identified with 196 being up-regulated and 94 being down-regulated in DBE groups as compared to LBE groups. The Kyoto encyclopedia of genes and genomes (KEGG) analysis revealed that these DEGs belong to several biological pathways including herpes simplex infection (toll-like receptor 3 [TLR3], cyclin-dependent kinase 1, etc.) and influenza A (TLR3, radical S-adenosyl methionine domain containing 2, myxovirus [influenza virus] resistance 1, etc.). Genes related to stress response (ceremide kinase like) and nutrient metabolism (phosphoenolpyruvate carboxy-kinase 1, methylmalonic aciduria [cobalamin deficiency] cblB type, glycine receptor alpha 2, solute carrier family 7 member 11, etc.) were also identified to be differentially expressed.ConclusionThe current results provide new insights regarding hepatic molecular functions related to different intensity of brown eggshell color in aged laying hens. These insights will contribute to future studies aiming to optimize brown eggshell coloration in aged laying hens.

Effects of Microbial Phytase Supplementation on Egg Production and Egg Quality in Hy-line Brown Hens During the Late Laying Period.

The objective of this study was to evaluate the effects of microbial phytase on egg production and egg quality in older hens. A total of 216, 63-week-old Hy-line brown laying hens were distributed in a randomized complete design 10-week feeding trial of 3 dietary treatments with 12 replications per treatment and 6 hens per replication. The 3 dietary treatments were corn-soybean meal-based diets supplemented with 0% (CON), 0.06% (TRT1), and 0.12% (TRT2) microbial phytase. Significantly higher hen-day egg production was observed in the TRT1 treatment compared to CON (P<0.05), except during the first two weeks of the experiment. During weeks 3, 4, and 9, TRT2 had a greater hen-day egg production percentage than CON (P<0.05). The damaged egg ratio was not affected. The egg quality parameters (e.g., eggshell color, eggshell strength, albumen height, egg weight, and the Haugh unit) were affected by microbial phytase supplementation (P<0.05). However, there were no significant effects on the eggshell thickness and yolk color. In conclusion, microbial phytase supplementation to the diets of older hens could improve production performance, extend the peak laying period, and alter the egg quality parameters.

An EAV-HP insertion in the 5ʹ flanking region of SLCO1B3 is associated with its tissue-expression profile in blue-eggshell Yimeng chickens (Gallus gallus)

We previously reported that blue eggshell color in chickens is associated with a partial endogenous retroviral (EAV-HP) insertion in the promoter region of the solute carrier organic anion transporter family member 1B3 (SLCO1B3) gene. The EAV-HP sequence includes numerous regulatory elements, which may modulate the expression of adjacent genes. To determine whether this insertion influences the expression of neighboring genes, we screened the expression of solute carrier organic anion transporter family members 1C1, 1B1 (SLCO1C1, SLCO1B1), and SLCO1B3 in 13 and 10 tissues from female and male Yimeng chickens, respectively. We observed that the insertion only significantly modulated the expression of SLCO1B3 and did not majorly affect that of SLCO1C1 and SLCO1B1. High expression of SLCO1B3 was detected in the shell gland, magnum, isthmus, and vagina of the oviduct in female blue-eggshell chickens. We also observed ectopic expression of SLCO1B3 in the testes of male chickens. SLCO1B3 is typically highly expressed in the liver; however, the EAV-HP insertion significantly reduces SLCO1B3 expression. As a liver-specific transporter, a reduction in the expression of SLCO1B3 may affect liver metabolism, particularly that of bile acids. We also detected higher ectopic expression of SLCO1B3 in the lungs of birds heterozygous for the EAV-HP insertion than in homozygous genotypes. In conclusion, we confirmed that the EAV-HP insertion modifies SLCO1B3 expression, and showed, for the first time, similar expression profile of this gene in all parts of the oviduct in females and testis in males. We also observed different levels of SLCO1B3 expression in the liver, which were associated with the EAV-HP insertion, and significantly higher expression in the lungs of birds with heterozygous genotype. The effects of these changes in the SLCO1B3 expression pattern on the function of the tissues warrant further investigation.

토종닭 12계통 난질의 일반능력 및 상관관계 분석

In this study, sixteen egg quality traits, including egg weight, albumen weight, yolk weight, eggshell weight, albumen weight ratio, yolk weight ratio, eggshell weight ratio, yolk color, eggshell color, egg height, egg width, shape index, albumen height, Haugh unit, eggshell thickness, and eggshell strength were investigated in 12 strains of Korean native chicken using 600 eggs from birds at 38 weeks of age. Results showed that the Korean White Leghorn F strain had the highest egg weight of 62.7 g and the lowest (47.5 g) was observed in the Korean native chicken W strain. The Haugh unit was significantly different between strains. The mean Haugh unit for Korean native chicken ranged between 84.2 (L strain) and 76.0 (F strain), with an overall average of 79.9. Eggshells were the thinnest in Korean Rhode Island Red C and D strains (0.342 mm), whereas the highest eggshell thickness (0.393 mm) was observed in the Korean White Leghorn K strain. Korean Rhode Island Red C and D strains had low egg strength compared to that of other strains. Korean Cornish and Korean native chicken showed significant differences in egg quality traits between strains within breeds. Positive correlation coefficients were observed between egg weight and egg quality traits. The traits for color showed zero or low correlations with most egg quality traits. Egg shape index showed no correlation with most egg quality traits. Albumen height and the Haugh unit showed a positive correlation with albumen traits. Eggshell strength showed a positive correlation with eggshell traits.

Hoopoe Upupa epops male feeding effort is related to female cosmetic egg colouration

Avian eggshell colouration might function as a post‐mating sexually selected signal of female quality, influencing male parental investment and, hence, reproductive success. This hypothesis has been tested for intrinsic eggshell pigments as biliverdin (blue‐green colouration) and/or protoporphyrin (brown coloured spots), but never for colourations applied post‐laying. Post‐laying staining colouration due to, for instance, uropygial secretion of the female could reflect its phenotypic properties and, thus, might be a cue for male investment in reproduction. In hoopoes, the uropygial gland of incubating females hosts symbiotic bacteria that are responsible for the brown colour of their uropygial secretion and of the eggshells, as they cover their bluish‐grey eggshells with gland secretion after laying. The secretion protects embryos from pathogenic trans‐shell infections and, thus, egg colouration may function as a cue or even as a post‐mating sexually selected signal of antimicrobial potential in hoopoes. In a wild hoopoe population breeding in nest boxes in Spain, we test this hypothesis by exploring whether egg colour predicts male parental investment. In accordance with the hypothesis, we found that the amount of food provided by males to incubating females was higher in nests with less saturated eggshell colours. This relationship was affected by female body condition. High quality females in terms of body condition and/or in secretion colour obtained better males in terms of provisioning effort during incubation. Given that eggshell saturation is negatively related to density of bacterial symbionts in uropygial secretions, one possibility is that males may regulate their parental investment in accordance to the expected characteristics of mutualistic bacteria hosted in uropygial glands and deposited on eggshells. We discuss alternative explanations for our results, concluding that the post‐mating sexual selection hypothesis is the most likely but experimental modification of egg colour is needed to test it further.

Hybrid Versus Autochthonous Turkey Populations: Homozygous Genomic Regions Occurrences Due to Artificial and Natural Selection.

Simple SummaryIn this study we investigate the genomic differentiation of traditional Mexican turkey breeds and commercial hybrid strains. The analysis aimed to identify the effects of different types of selection on the birds’ genome structure. Mexican turkeys are characterized by an adaptive selection to their specific original environment; on the other hand, commercial hybrid strains are directionally selected to maximize productive traits and to reduce production costs. The Mexican turkeys were grouped in two geographic subpopulations, while high genomic homogeneity was found in hybrid birds. Traditional breeds and commercial strains are clearly differentiated from a genetic point of view. Inbreeding coefficients were here calculated with different approaches. A clear effect of selection for productive traits was recorded.The Mexican turkey population is considered to be the descendant of the original domesticated wild turkey and it is distinct from hybrid strains obtained by the intense artificial selection activity that has occurred during the last 40 years. In this study 30 Mexican turkeys were genomically compared to 38 commercial hybrids using 327,342 SNP markers in order to elucidate the differences in genome variability resulting from different types of selection, i.e., only adaptive for Mexican turkey, and strongly directional for hybrids. Runs of homozygosity (ROH) were detected and the two inbreeding coefficients (F and FROH) based on genomic information were calculated. Principal component and admixture analyses revealed two different clusters for Mexican turkeys (MEX_cl_1 and MEX_cl_2) showing genetic differentiation from hybrids (HYB) (FST equal 0.168 and 0.167, respectively). A total of 3602 ROH were found in the genome of the all turkeys populations. ROH resulted mainly short in length and the ROH_island identified in HYB (n = 9), MEX_cl_1 (n = 1), and MEX_cl_2 (n = 2) include annotated genes related to production traits: abdominal fat (percentage and weight) and egg characteristics (egg shell color and yolk weight). F and FROH resulted correlated to each other only for Mexican populations. Mexican turkey genomic variability allows us to separate the birds into two subgroups according to the geographical origin of samples, while the genomic homogeneity of hybrid birds reflected the strong directional selection occurring in this population.

Expanding the eggshell colour gamut: uroerythrin and bilirubin from tinamou (Tinamidae) eggshells

To date, only two pigments have been identified in avian eggshells: rusty-brown protoporphyrin IX and blue-green biliverdin IXα. Most avian eggshell colours can be produced by a mixture of these two tetrapyrrolic pigments. However, tinamou (Tinamidae) eggshells display colours not easily rationalised by combination of these two pigments alone, suggesting the presence of other pigments. Here, through extraction, derivatization, spectroscopy, chromatography, and mass spectrometry, we identify two novel eggshell pigments: yellow–brown tetrapyrrolic bilirubin from the guacamole-green eggshells of Eudromia elegans, and red–orange tripyrrolic uroerythrin from the purplish-brown eggshells of Nothura maculosa. Both pigments are known porphyrin catabolites and are found in the eggshells in conjunction with biliverdin IXα. A colour mixing model using the new pigments and biliverdin reproduces the respective eggshell colours. These discoveries expand our understanding of how eggshell colour diversity is achieved. We suggest that the ability of these pigments to photo-degrade may have an adaptive value for the tinamous.

UK consumers' willingness to pay for laying hen welfare

PurposeThis study investigates UK consumers’ perception and willingness to pay (WTP) for egg attributes associated with laying hen welfare, namely with beak-trimming practices and injurious feather pecking (IP). The aim is to examine any change in WTP after improved consumer awareness.Design/methodology/approachBuilding upon existing literature, the authors designed an online survey in which the method of discrete choice experiment (DCE) was employed. The study includes two identical DCEs with the second being introduced after respondents were presented with an educational excerpt about beak-trimming practices, on farm IP occurrence and the docile nature of white egg laying hens – reducing IP.FindingsThe mixed logit regression model demonstrated that consumers' WTP for egg attributes associated with beak trimming and IP decreased in the second DCE (12.6% for organic and 2.55% for free-range). For eggshell colour, the analysis revealed a shift from a preference to brown eggs to indifference between eggshell colours.Originality/valueOverall, UK consumers have a preference in higher hen welfare resulting in a decrease in WTP once they are aware of welfare losses in current systems; however, more insights are required in terms of the promotion of white shelled eggs as a means of reducing IP on UK farms.

Effect of different tea polyphenol products on egg production performance, egg quality and antioxidative status of laying hens

This study was conducted to determine the effects of different tea polyphenol (TP) products on egg production performance, egg quality and antioxidative status of laying hens. A total of 840 Lohmann pink shell laying hens (36-week-old) were randomly divided into 7 treatments for a 12-week feeding trial. The control group was fed a basal diet (no exogenous TP addition), and the experimental groups were fed the basal diet supplemented with approximately 1000 mg/kg of 6 types of tea polyphenols. The TP contents in 6 experimental diets were 1086.1, 944.2, 1111.4, 1037.9, 1074.1, and 1081.7 mg/kg and the caffeine concentrations were 4.4, 17.2, 30.9, 37.5, 73.8, and 128.5 mg/kg, respectively. In terms of performance, TP (except 1086.1 and 1074.1 mg/kg) reduced (P < 0.05) the average daily feed intake (ADFI) and the feed conversion ratio (FCR) during 1–4 week. Dietary TP supplementation at 944.2, 1074.1 and 1081.7 mg/kg increased the dirty egg rate (P < 0.01) and the addition of 1111.4, 1037.9 and 1081.7 mg/kg TP in basal diet decreased saleable egg rate (P < 0.05) during week 5 to week 8. The eggshell strength and eggshell weight of fresh egg at week 0, week 4 and week 8 were decreased by dietary TP supplementation (P < 0.05), with the TP groups (1074.1 and 1081.7 mg/kg) exhibiting the lowest eggshell strength and shell weight at week 0 and week 8. In addition, the lightness (L*) of eggshell color was decreased (P < 0.05), while the redness (a*) and yellowness (b*) was increased as TP intake increased (except 1086.1 and 1037.9 mg/kg) (P < 0.05). The albumen weight, yolk color, relative yolk weight and HU (Haugh unit) of fresh eggs at week 8 were higher or decreased (P < 0.05) as TP intake (except 1086.1 and 1074.1 mg/kg) increased. After 20-day storage, the eggshell strength, eggshell thickness and egg weight of eggs from hens fed the diets supplemented more than 1111.4 mg/kg TP (except 1074.1 mg/kg) were lower (P < 0.05) than those from control group. No effect of TP administration was found on serum glutathione peroxidase (GSH-PX), total antioxidant capacity (T-AOC), and malondialdehyde (MDA) concentrations. The results indicated that adding different tea polyphenol products in layers’ diet led to a lower ADFI and improved FCR in a dosage-dependent manner during the first 4 weeks, but it impacted the hens’ egg quality.

Dietary yeast β-glucan supplementation improves eggshell color and fertile eggs hatchability as well as enhances immune functions in breeder laying hens

The study was conducted to evaluate the effects of dietary yeast β-glucan (YG) on performance and immune functions in breeder hens in a non-challenged setting. A total of 512 43-week-old Hy-Line Brown breeder hens were assigned into four treatments, and fed a basal diet with YG at 0, 50, 100 and 200 mg /kg for 8 weeks, respectively. Results showed that supplementation of YG did not affect production performance, but linearly increased hatchability (P < 0.05). Compared with the control, hens fed with 200 mg/kg YG had improved eggshell color and reduced mortality. Moreover, feeding 200 mg/kg YG significantly (P < 0.05) enhanced lymphocyte proliferation response to LPS, increased the percentage of peripheral blood CD3+ T cells and phytohemagglutinin (PHA) skin response; remarkably down-regulated splenic TLR4, IL-6 and TGF-β mRNA levels while upregulated TLR6 and IFN-γ mRNA levels (P < 0.05). In addition, inclusion of YG at 200 mg/kg considerably promoted the production of serum cytokines, total IgA, and specific antibody titers against BSA, AIV and NDV vaccine (P < 0.05). These results suggested that dietary inclusion of 200 mg/kg YG could improve eggshell color and fertile eggs hatchability and enhance cellular and humoral immune function of breeder hens in a nonchallenged setting without disturbing immune homeostasis.

Individuality in Egg Colouration of Black-Headed Gulls Chroicocephalus ridibundus across the Years Confirmed through DNA Analyses

The eggshell colouration among and within certain bird species is highly variable. Although many studies have addressed this variation, the reasons for it remain largely unclear. Consistent individual differences in egg colouration may improve the ability of colonially breeding birds to recognise their clutch among other neighbouring nests. Moreover, in species with a high incidence of intraspecific brood parasitism, such as the Black-head Gull Chroicocephalus ridibundus, egg colouration patterns may allow parents to expel foreign eggs from their own clutch. Here, we used standardised photography and image processing, including UV spectral information, to investigate egg colour patterns in female Black-headed Gulls (476 eggs in 170 clutches) during four breeding seasons, from 2015 to 2018 in NE Germany. We confirmed maternity by comparing DNA extracted from eggshells with feathers from the breeding female. Our results showed a greater similarity of eggs within a clutch than among clutches (ANOSIM: R = 0.43, P = 0.001). Black-headed Gulls showed consistent individual-specific eggshell colour pattern across consecutive breeding seasons. Genetic analyses further revealed one foreign egg was present in three out of 25 clutches (12%), but these eggs were not expelled by the gulls, possibly because these eggs did not differ significantly in colouration from their own. Additionally, we conducted a clutch exchange experiment to assess the reaction of the breeding pair to a foreign clutch. After 21 neighbouring clutches had been exchanged, adults came back immediately and incubated the interchanged clutch without any negative reaction. It seems that they do not use the specific colour pattern for recognition of their clutches, but possibly use other cues that remain to be investigated. While the function of individual egg colour patterns remains unclear, our results strongly suggest colour variation is driven by internal rather than external factors in this colonially breeding species.

Yield Performance, Laying Behaviour Traits and Egg Quality of Purebred and Hybrid Hens Reared under Outdoor Conditions.

Simple SummaryNowadays, the consumer has a choice of table eggs depending on rearing system, egg size, eggshell and yolk colour, produced by a few worldwide hybrid strains. Many countries have a historic poultry tradition, with breeds used for domestic egg production. In Northern Italy, in the Po river plain, a relevant part of the maize production was used also for poultry feeding and many breeds existed in the last centuries. At present, the Veneto region shows an important poultry biodiversity with many breeds, whose egg production traits are not well known. A comparison between purebred and hybrid hens throughout the laying period was carried out in order to study yield performance, laying behavioural traits and egg quality. The knowledge of the variation of these traits is useful for managing the breeding of these genotypes and the offer to the consumers. The local breeds showed differences from hybrid hens both for yield performance and laying behaviour and for both egg size and external and internal quality.This study compared the yield performance, laying behavioural traits and egg quality of purebred and hybrid hens (from 28 until 44 weeks of age, considering four periods) reared under outdoor conditions. The four genotypes were reared on the same trial station, on four areas (one genotype/area), and under the same environmental conditions from hatching until the end of the trial. Italian dual-purpose purebred (Ermellinata di Rovigo—ER and Robusta maculata—RM) and hybrid (Hy-Line Brown—HB and Hy-Line White 36—HW) hens (flock size: 70 birds/genotype) were allowed outdoors (4 m2/bird, good pasture during the growing period and poor pasture throughout the laying period, according to the season) and indoors (0.20 m2/bird, five birds/individual nest) and fed commercial feed. Significant (p < 0.01) differences among genotypes were found. The hybrids showed a higher laying rate and hen-day edible egg mass, and a lower body weight than the purebreds. Broken and out-of-nest egg% were higher in RM and HW than ER and HB, respectively. Double-yolk egg% was higher in hybrids than in purebreds. The eggshell colour varied among brown eggshell ER, RM, and HB. The ER showed the lowest shape index. With aging, the yolk to albumen ratio linearly increased in all groups, eggshell% changed in ER, HW, RM (cubic) and in HB (linear). The purebreds showed meat spots% higher than blood spots; HW showed the lowest total inclusion%. In conclusion, according to an egg scoring evaluation (egg weight = medium-large size, yolk to albumen ratio = 0.5, total inclusions = none), HW showed a higher quality than HB and RM, and ER was intermediate. The RM hens showed the highest% of defective eggs, especially for overcrowding at nest, HB showed the lowest. Under outdoor conditions the laying behaviour of the purebred hens and the nest management are important factors for the saleable egg rate.

Interest of using imputation for genomic evaluation in layer chicken

With the availability of the 600K Affymetrix Axiom high-density (HD) single nucleotide polymorphism (SNP) chip, genomic selection has been implemented in broiler and layer chicken. However, the cost of this SNP chip is too high to genotype all selection candidates. A solution is to develop a low-density SNP chip, at a lower price, and to impute all missing markers. But to routinely implement this solution, the impact of imputation on genomic evaluation accuracy must be studied. It is also interesting to study the consequences of the use of low-density SNP chips in genomic evaluation accuracy. In this perspective, the interest of using imputation in genomic selection was studied in a pure layer line. Two low-density SNP chip designs were compared: an equidistant methodology and a methodology based on linkage disequilibrium. Egg weight, egg shell color, egg shell strength, and albumen height were evaluated with single-step genomic best linear unbiased prediction methodology. The impact of imputation errors or the absence of imputation on the ranking of the male selection candidates was assessed with a genomic evaluation based on ancestry. Thus, genomic estimated breeding values (GEBV) obtained with imputed HD genotypes or low-density genotypes were compared with GEBV obtained with the HD SNP chip. The relative accuracy of GEBV was also investigated by considering as reference GEBV estimated on the offspring. A limited reordering of the breeders, selected on a multitrait index, was observed. Spearman correlations between GEBV on HD genotypes and GEBV on low-density genotypes (with or without imputation) were always higher than 0.94 with more than 3K SNP. For the genetically closer, top 150 individuals for a specific trait, with imputation, the reordering was reduced with correlation higher than 0.94 with more than 3K SNP. Without imputation, the correlations remained lower than 0.85 with less than 3K and 16K SNP for equidistant and linkage disequilibrium methodology, respectively. The differences in GEBV correlations between both methodologies were never significant. The conclusions were the same for all studied traits.

The effect of breed and age on the gloss of chicken eggshells

The monitoring of eggshell quality is important mainly in terms of production economy. Eggshell appearance is one of the most characteristics, influencing the purchasing behavior of consumers. Besides numerous eggshell appearance quality (color, shape, etc.), gloss is an important trait to reflect the eggshell appearance. In this study, 2 experiments were conducted to investigate the effect of breed and age on the gloss of eggshells. In experiment 1, we compared the eggshell gloss of 7 chicken breeds. In experiment 2, 105 Wanan (WA) chickens were raised, and 1 egg was collected from each individual at 26, 32, 40, and 50 wks of age. Eggshell gloss, color (L*, a*, b*), cuticle coverage (ΔE*ab), and thickness were measured. The results of experiment 1 showed that the average gloss values were highly variable among different breeds, and the highest was found in WA (gloss unit [GU] = 8.12), almost 2.5 folds as many as the lowest in Rhode Island Red (GU = 3.23). Also, the eggshell gloss of the local chicken breeds was significantly higher than the highly selected lines of egg-type chicken breeds (P < 0.001). In experiment 2, the results showed that gloss ranged from 9.08 GU to 12.12 GU with a variation of 28.38 to 39.71%. It fluctuated with the increasing age of hens and had the peak value at 26 wk. But, the correlation analysis between eggshell gloss and other eggshell quality traits were very low (−0.07 to 0.25). This study laid a foundation for improving the uniformity and intensity of eggshell gloss for breeders.

The Impact of Eggshell Colour on the Quality of Table and Hatching Eggs Derived from Japanese Quail.

Simple SummaryThe eggshell is the first element in the assessment of both table and hatching eggs. It may be influenced by many factors, i.e., the birds’ genotype, their utility type, rearing system, environmental conditions and feed mineral additives. However, the eggshell colour may affect the shell itself as well as both the quality of eggs and their biological value. Among the standard coloured eggs of Japanese quail, the eggs with a uniform shell can be found, in white to celadon colour. Consumers have no preferences in this regard, they are satisfied with the small size and taste of the egg. However, breeders believe that these eggs may be worse in the case of internal quality, both in terms of consumption and hatching. The aim of the study was to evaluate table and hatching eggs of Japanese quails (Coturnix coturnix japonica) depending on the eggshell colour. It seems that Japanese quail eggs with uniform “blue” shells do not appear to be of poorer quality than those with brown-spotted shells if they are intended for consumption. However, in the aspect of hatching eggs, the eggshell colour may modify the hatching results and body weight of the chicks obtained.The aim of the study was to evaluate table and hatching eggs of Japanese quails (Coturnix coturnix japonica) depending on the eggshell colour. The research was carried out in two stages, in terms of table eggs’ quality and their biological value as hatching eggs depending on the eggshell colour. In both stages, 300 Japanese quail eggs were used in each (600 in total) divided into two equal groups: with a brown-spotted shell, with a uniform shell in shades of blue. In the 1st stage, quality characteristics of the whole egg (weight, specific gravity, proportions of particular elements), yolk (weight, colour, index), albumen (weight, height) and shell (colour, strength, weight, thickness, density) were evaluated. In the 2nd stage, eggs were incubated under standard conditions and following biological characteristics were analyzed: eggs fertility, embryo mortality, hatchability of fertile and set eggs, body weight of hatchlings and their proportion in egg weight. The shell colour, “blue” or spotted, of Japanese quail eggs, does not appear to influence their quality if they are intended for consumption. However, the hatching results and body weight of obtained chicks of Japanese quail may be affected by the eggshell colour.

Fitting different visual models to behavioral patterns of parasitic egg rejection along a natural egg color gradient in a cavity-nesting host species

Avian brood parasites lay their eggs in other birds’ nests, and hosts can mitigate the fitness cost of raising unrelated offspring by rejecting parasitic eggs. A visually-based cognitive mechanism often thought to be used by hosts to discriminate the foreign egg is to compare it against the hosts’ own eggshell by size, shape, maculation, and/or ground coloration (i.e., absolute chromatic contrast). However, hosts may instead discriminate eggs based on their colors along a scale of natural avian eggshell coloration (i.e., directional chromatic contrast). In support of this latter visual process, recent research has found that directional chromatic contrasts can explain some host species’ rejection behavior better than absolute chromatic or achromatic contrasts. Here, for the first time, we conducted an experiment in a cavity-nesting host species to test the predictions of these different visual mechanisms. We experimentally parasitized nests of the Common Redstart Phoenicurus phoenicurus, a regular host of a mimetic-egg laying Common Cuckoo Cuculus canorus host-race, using painted, immaculate 3D-printed model eggs in two geographically distant areas (Finland and Czech Republic). We found that directional chromatic contrasts better explained rejection behaviors in both parasitized (Finland) and non-parasitized (Czech Republic) host populations, as hosts rejected eggs that were noticeably browner, but not eggs that were noticeably bluer, than redstart eggs. These results support the paradigm of a single rejection threshold predicted by the directional chromatic contrast model and contribute to a growing generality of these patterns across diverse avian host-brood parasite systems.

Breed and feed affect amino acid contents of egg yolk and eggshell color in chickens

Genetic and environmental factors regulate hen egg traits. To demonstrate the possibility of producing designer eggs through genetic and environmental factors, we investigated the effects of breed and feed on egg traits using 2 chicken breeds, Rhode Island Red (RIR) and Australorp (AUS), and 2 feeds, mixed feed and fermented feed. A total of 40 eggs were collected at 33 wk of age (0 mo under mixed feed) and 1, 1.5, and 2 mo after switching to fermented feed. Two-way ANOVA mixed design was used to evaluate 10 egg traits: weight, length of the long axis, length of the short axis, eggshell weight, yolk weight, albumen weight, eggshell thickness, eggshell lightness, redness, and yellowness, and 19 yolk amino acids. The results revealed significant breed effects on eggshell redness and yellowness, with higher values of these traits in RIR eggs compared with AUS eggs. There was a significant effect of feed on eggshell lightness, with a lighter color observed under fermented feed compared with mixed feed. Significant effects of breed and breed × feed were found for yolk cysteine content. Eggs from AUS had a higher yolk cysteine content than those from RIR. The cysteine content in AUS eggs increased gradually after starting fermented feed, although RIR remained relatively constant over time. These findings suggest that it is possible to produce designer eggs with enriched components, including yolk amino acids, by adjusting both genetic and environmental factors. This represents a first step in understanding the mechanisms underlying the production of value-added eggs in chickens.

Response of three laying hen genotypes to two feed calcium levels

The present study aimed to evaluate the effect of two dietary Ca levels (3.00% vs 3.50%) in three hen genotypes (ISA Brown, Bovans Brown and Moravia BSL) on their laying performance and quality of their eggs. In order to evaluate the response to dietary Ca, an experiment was conducted with 300 laying hens. One hundred birds from each genotype were divided into 10 replicates (10 birds/cage/Ca level). To reveal the differences, the following characteristics were measured: hen-day egg production percentage, daily feed intake, egg weight, albumen and yolk weights, Haugh unit, eggshell colour, eggshell weight, eggshell thickness, eggshell strength, egg shape index and eggshell index. A higher Ca level significantly increased the hen-day egg production percentage of Bovans Brown and Moravia BSL, while ISA Brown laying hens had the higher egg production percentage at a lower dietary Ca level (85.97% vs 82.41%). No significant effect of dietary Ca level was observed on any internal egg quality measurements except the Haugh unit. However, the dietary Ca level significantly affected some of external egg quality measurements, namely eggshell colour (P &amp;lt; 0.001), eggshell weight (P = 0.003) and eggshell strength (P = 0.012). The results of the present study show that laying performance and egg quality parameters responded differently according to hen genotype and dietary Ca level. Bovans Brown and Moravia BSL laying hens required higher levels of Ca to keep egg production high, while the eggshell quality measurements were better at the lower dietary Ca level. Thus, it is recommended to adjust the Ca levels in feed to the nutritional requirements of laying hens.

토종종계에 있어 조우성 개체와 만우성 개체간 생산능력 비교 고찰

Currently, feather-sexing, which is based on differences in feather development at hatching, is a widely used chick sexing method in the poultry industry. For effective chicken feather-sexing, paternal early-feathering (EF) chickens and maternal late-feathering (LF) chickens must be bred. Therefore, it is critical to identify the effect of EF and LF patterns on production traits in chickens. Thus, the purpose of this study is to analyze and compare the production performances between 522 EF and 232 LF chickens in order to establish the Korean native chicken feather-sexing lines. The results showed that the survival rate of the LF group was significantly higher than that of the EF group from hatching to 52 weeks of age (<italic>P</italic>&lt;0.05). Body weight, however, was not significantly different between the two groups at all ages. LF and EF groups did not significantly differ in age at first egg laying. However, the hen-day and hen-housed egg production of the LF group were significantly higher than those of EF group (<italic>P</italic>&lt;0.01). No significant differences were found between the EF and LF groups in all egg quality indicators such as egg weight, eggshell color, albumin height and Haugh unit. Because the breeding target of Korean native commercial chicken is meat-type chicken, feather-sexing strains of Korean native chicken should be established using weighing-based paternal EF lines and laying-based maternal LF lines. Therefore, these results are critical for establishing desirable and effective feather-sexing strains.

Concentration of egg white antimicrobial and immunomodulatory proteins is related to eggshell pigmentation across traditional chicken breeds

Eggshell colour, quality, and biosafety of table eggs are of significant commercial interest. To date, there have been few studies investigating the relationship between eggshell pigmentation and internal egg quality in commercially bred birds. Moreover, the genetic basis and mechanisms behind the effects of extrinsic factors on deposition of antimicrobial compounds in egg white and eggshell pigments are not fully understood. In the present study, we evaluate the effect of chicken breed identity, eggshell pigmentation and the role of extrinsic factors (year and breeder identity) on variability in the concentrations of 2 major egg white antimicrobial proteins (AMPs), lysozyme (LSM), and ovotransferrin (OVOTR), across 23 traditional chicken breeds. We found that chicken breed identity and eggshell pigmentation explained most variability in the concentration of egg white LSM and OVOTR. Year and breeder identity were also significant predictors of egg white LSM and OVOTR variability, and showed selective effects on the deposition of both AMPs in egg white. We also documented a positive correlation between concentration of egg white LSM and eggshell cuticle protoporphyrin in tinted and dark brown eggs, but not in brown, white, and blue eggs. We assume that a combination of both intrinsic genetic and hormonally regulated extrinsic factors is responsible for this relationship and for the variability in egg white AMPs. In this study, we demonstrate the existence of a relationship between eggshell pigmentation and egg white AMPs content in the eggs of traditional chicken breeds that may advertise the egg's antimicrobial potential and biosafety. These findings provide novel insights into the relationship between eggshell pigmentation and egg internal quality and may stimulate the recovery and exploitation of traditional chicken breeds for egg production, where the demands for egg quality and biosafety, in conjunction with animal welfare, are a priority.