The Effect of the Type of Alternative Housing System, Genotype and Age of Laying Hens on Egg Quality

Analysis of the Quality and Chemical Composition of Double-Yolked Eggs Compared to Those of a Normal Structure

The study material consisted of 360 eggs from a reproductive flock of meat-type hens; 240 were double-yolked eggs and 120 were single-yolked as a control group. The eggs were numbered individually and then analysed for their quality in terms of characteristics of the whole egg (weight, shape index, specific gravity), shell (colour, strength, weight, density), albumen (pH, height, weight, Haugh units) and yolk (colour, weight, shape index, pH). During the analyses, yolks were sampled for analyses including basic composition, fatty acid profile (by gas chromatography) and fatty acid indices. It was found that double-yolked eggs differed significantly from single-yolked ones in terms of weight, proportion of individual elements in the egg weight, total protein content in the yolks as well as in terms of the fatty acid profile and their indices both due to the presence or absence of two yolks and in the context of the individual yolks analysed. The results indicate the possibility of using double-yolked eggs as table eggs due to the absence of negative effects stemming from being double-yolked and the increased content of biologically important components such as fatty acids.

Comparison of Fatty Acid Profile in Egg Yolk from Late-Age Hens Housed in Enriched Cages and in a Free Range System

In recent years, the free-range system for laying hens has increased, driven by societal sensitivity to animal welfare. This study aimed to comparatively analyze the total lipid, cholesterol, and fatty acid composition of egg yolks of late-age laying hens reared in enriched cages (C) and the free-range system (FR). Eggs were collected from Lohmann Brown Classic hens at the 68th, 70th, 72nd, and 74th week of age. The concentrations of total lipids and cholesterol were not affected (p > 0.05) by either factor. Egg yolk from the FR group showed lower (p < 0.01) monounsaturated fatty acids and higher (p < 0.01) polyunsaturated fatty acid (PUFA) compared with that of the C group. From a nutritional point of view, the PUFA n-6/n-3 and the PUFA/SFA ratios of egg yolk from the FR group were favorably lower and higher (p < 0.01) compared with the C one. Conversely, hen age did not affect (p > 0.05) the fatty acid composition of yolks. Interactions between factors were found for total n-3 and n-6 PUFA and the n-6/n-3 ratio (p < 0.01), as well as the thrombogenic index (p < 0.05). In conclusion, the results confirmed that the free-range system may improve the nutritional yolk fatty acid profile and its positive impact on human health.

Influence of Genotype on Productivity and Egg Quality of Three Hen Strains Included in a Biodiversity Program

The aim of the study was to evaluate the effect of genotype on the productivity and egg quality of three hen strains included in the genetic resource protection program in Poland. The study encompassed populations of laying hens, i.e., Rhode Island Red/RIR (R-11 and K-22) and Rhode Island White (A-33). The analysis over five generations included the basic production traits, i.e., the weight of the birds at 20 weeks (g), egg weights at 33 and 53 weeks, sexual maturity, the number of eggs laid up to 56 weeks of age, and hatchability parameters. In addition, the effective population size (Ne) and flock homozygosity coefficient (Fx) were calculated for each breed. Population health during the rearing and production periods was also recorded. The study also determined egg content and shell quality traits in relation to the age of the hens. The birds were kept on litter at a stocking rate of 5 hens/m2 and fed ad libitum with a standard feed mixture for hens. Based on the results, it was concluded that the evaluated hen populations (R-11, K-22, and A-33) are valuable strains, representing a reservoir of unique phenotypic and egg quality traits. It was shown that the random mating system used in the reproduction of flocks effectively protects the populations from an increase in the degree of inbreeding. An influence of hens' origin (genotype) and age on the performance results, as well as egg quality traits, was found. Over five generations, the evaluated hen strains were characterized by high survival rates (above 98%). The study also found a large variation between the R-11 and K-22 strains and the A-33 strain in terms of the evaluated performance traits, especially in the body and egg weights, sexual maturity age, and laying performance of hens. The earliest to start laying were hens from the K-22 strains, which also showed significantly (p ≤ 0.05) higher laying performances compared to R-11 hens. The results also indicate that the quality of eggs from hens of the compared strains varied. This was particularly true for such traits as shell color; egg, shell, and yolk weight; and shell quality. It was also shown that many egg and shell quality traits change with the age of the hens. The analysis of the obtained data indicates that the adopted methods of conservative breeding for these populations have influenced the success of the conservation program.

The eggshell defect as a factor affecting the egg quality after storage

The aim of the study was to assess the influence of shell defects on the quality of eggs after storage. The study material consisted of 1,800 brown-shelled eggs from cage rearing system which were candled on the day of laying to determine the shell quality. Eggs with the 6 most common shell defects (external crack, severe stripe marks, points, wrinkled, pimples, sandy) and eggs without defects (control group) were then stored for 35 days at 14°C and 70% humidity. The weight loss of eggs was monitored every 7 days, and the quality characteristics of whole eggs (weight, specific gravity, shape), shell (defects, strength, color, weight, thickness, density), albumen (weight, height, pH) and yolk (weight, color, pH) of 30 eggs from each group were analysed at the beginning (0 days) and after 28 and 35 days of storage. The changes resulting from water loss (air cell depth, weight loss, shell permeability) were also evaluated. The study showed that all investigated shell defects significantly influenced the characteristics of the whole egg during the storage, modifying traits such as specific gravity, water loss, shell permeability, albumen height and pH, as well as proportion, index and pH of the yolk. Furthermore, an interaction between time and the shell defects presence was found.

Microbiome comparison of Dermanyssus gallinae populations from different farm rearing systems and the presence of common endosymbiotic bacteria at developmental stages

The hematophagous arthropod, Dermanyssus gallinae (Poultry red mite, PRM) can cause remarkable economic losses in the poultry industry across the globe. Although overall composition of endosymbiotic bacteria has been shown in previous studies, how farm habitats influence the microbiome remains unclear. In the present study, we compared the bacterial communities of D. gallinae populations collected from the cage and free-range farms using next-generation sequences targeting the V3-V4 hypervariable region of the 16S rRNA gene. The QIIME2 pipeline was followed in bioinformatic analyses. Proteobacteria represented a great majority of the total bacterial community of D. gallinae from both farming systems. More specifically, Bartonella-like bacteria (40.8%) and Candidatus Cardinium (21.5%) were found to be predominant genera in free-range and cage rearing systems, respectively. However, the microbiome variation based on farming systems was not statistically significant. In addition, the presence of the five common endosymbiotic bacteria (Wolbachia, Cardinium, Rickettsiella, Spiroplasma, and Schineria) was screened in different developmental stages of D. gallinae. Cardinium was detected in all developmental stages of D. gallinae. On the other hand, Wolbachia and Rickettsiella were only found in adults/nymphs, but neither in the eggs nor larvae. To our knowledge, this study provides the first microbiome comparison at genus-level in D. gallinae populations collected from different farm habitats and will contribute to the knowledge of the biology of D. gallinae.

Data mining-based discriminant analysis as a tool for the study of egg quality in native hen breeds

Despite the wide biodiversity of avian species of zootechnical interest in Spain, projects aimed at characterizing these genotypes and their products are necessary. External and internal egg quality traits were measured in 819 eggs laid by hens of 10 different genotypes: White, Franciscan, Black and Partridge varieties of Utrerana, Blue Andalusian, Spanish White-Faced, Andalusian Tufted White and Black varieties, Araucana; and Leghorn Lohmann LSL-Classic lineage (commercial hybrid line) hen breeds. After multicollinearity analysis of egg quality-related traits was performed (VIF ≤ 4), major diameter, minor diameter, egg weight, and albumen height were deemed redundant explanatory variables and discarded. A stepwise discriminant canonical analysis was developed to cluster eggs across hen genotypes considering egg quality attributes. Shell a* and b* variables reported the highest discriminant power (Wilks' lambda: 0.699 and 0.729, respectively). The first two discriminant functions captured 60.48% of the variance across groups (F1: 39.36%; F2: 21.12%). Clear quality differentiation signs are evidenced for Mediterranean native breeds' eggs when compared to Leghorn's eggs. Consequently, this evidence of egg quality differentiation may favor the standardization of breed- and variety-linked distinctive products, which may open new market opportunities based on the existence of a wide spectrum of diet or culinary applications.

Dietary L-glutamine affects eggshell quality in the post-peak laying period

In the current study the hypothesis that 1.0% dietary inclusion of glutamine (Gln), a conditionally essential amino acid that influences protein synthesis and shows anti-osteoporotic effect, can influence eggshell quality was tested on laying hens in the post-peak laying period. A 30-week-old Bovans Brown hens were randomly assigned to control group or group supplemented with Gln in the form of alpha-ketoglutarate (10 g/kg) with 12 replicate cages (2 hens/cage) in each group. The experimental period lasted for 30 weeks, from the 31st to the 60th week of age of hens, when eggs were collected and selected eggshell quality indices were determined. While Gln supplementation had no effect on egg geometry and eggshell cracking force, the analysis of eggshell quality showed an increase of the eggshell thickness (P<0.01), porosity (P<0.01), eggshell specific surface (P<0.001) and positive changes in other mechanical parameters (decrease of eggshell stiffness and Young’s modulus, P<0.05 and P<0.01, respectively; increase of work needed to crack the eggshell, P<0.05). Changes in eggshell mineral composition, including an increase of Ca content (P<0.001), were also observed. In conclusion, the current study showed a beneficial effect of Gln on the eggshell thickness, calcification, and some mechanical parameters.

Bone and eggshell quality throughout an extended laying cycle in three strains of layers spanning 50 years of selection

Decades of intensive genetic selection in commercial layers has resulted in earlier maturation, while sustaining high production rates to 100 wks of age (woa). To support eggshell formation while maintaining a healthy skeletal frame, substantial adaptations of calcium metabolism in the hen are necessary. Thus, skeletal growth, bone density, and egg quality were compared in 3 strains of layers, with the Lohmann LSL-lite as the current commercial strain, the heritage Shaver white leghorn as the mid-2000s strain, and the white-leghorn derived Smoky Joes as the non-selected 1960s strain. Tibia and Femur (n = 4/strain) were collected at 12, 17, 20, 25, 45, 60, 75, and 100 woa. Bones were measured and weighed, with bone mineral density assessed within medullary (mBMD) and cortical (cBMD) regions of the tibia using micro-Computed Tomography. Egg analyses including weight, eggshell thickness (EST) and eggshell breaking strength (EBS), were conducted throughout lay. Blood samples were collected to measure plasma calcium immediately prior to lay (18 woa) and periodically throughout the laying cycle. Femur and tibia weight, or size, did not increase beyond 12 woa, indicating that all hens reached maximum skeletal size by this time. An interaction (P = 0.005) was observed between strain and tibia mBMD, as all three strains demonstrated an accumulation of medullary bone from 12 to 100 woa. Regarding egg weight, while Lohmann hen eggs displayed the highest quality at 26 woa, an elevation in egg weight in Lohmann and Shaver hens (P < 0.001) resulted in a decline in EST and EBS over time (P < 0.01). Yet, at 100 woa, no strain differed in EST or EBS, despite larger variations in cumulative egg numbers (P < 0.001). Plasma calcium levels were significantly elevated between the immature state and peak of lay but remained unchanged throughout lay in all strains. In conclusion, our results show that although genetic selection of layer hens resulted in tremendous improvement in productivity, no detrimental effects on cBMD or mBMD were observed throughout an extended laying period up to 100 woa.

Quality of free-range and commercial eggs subjected to different storage periods and temperatures

Abstract The objective was to evaluate the internal quality of eggs from commercial laying hens and free-range hens subjected to different storage periods and temperatures. For the experiment, 280 eggs were randomly distributed into different treatments, adopting a completely randomized design, in a 2 x 7 factorial arrangement of two temperatures, seven storage periods, totaling 14 treatments with 10 replications. The treatments consisted of two storage conditions: under refrigeration (6 ± 1.0ºC) and at room temperature (26.6 ± 1.0ºC). Eggs were analyzed for 30 days, with evaluations in different storage periods (0, 5, 10, 15, 20, 25 and 30 days). For each storage condition, 140 eggs were separated, 70 commercial eggs and 70 free-range eggs. There was a linear increase in egg weight loss, yolk weight, albumen pH, yolk pH, length and width of albumen and yolk of commercial and free-range eggs, as the storage period increased. There was a linear reduction in weight, height and albumen index and in the yolk index of commercial and free-range eggs as the storage period increased, with more pronounced responses for eggs stored at room temperature (P<0.05). Albumen percentage was linearly reduced only for commercial eggs (P<0.05). Eggs kept at room temperature reduce their quality after 15 days of storage, and the storage under refrigeration for 30 days is recommended to preserve the shelf life of the egg for consumption.

Effect of supplementation with dried fruit pomace on the performance, egg quality, white blood cells, and lymphatic organs in laying hens

The aim of the current study was to assess the impact of raspberry (RA), black currant (BC), and black chokeberry (CA) dried pomace, at 30 g per kg of feed, on performance, egg quality, white blood cells, heterophil:lymphocyte ratio, and lymphatic organs in Hy-Line laying hens. Hens fed a basal diet comprised the control group (CO). A total of 480, 42-week-old Hy-Line commercial hybrid laying hens were randomly divided into 4 equal groups differing in the diet: in control group (CO), the birds received a standard diet, in groups CH, BC and RA, the birds were fed with a standard diet enriched with 30 g/kg of dried fruit pomace: Black chokeberry, black currant, and raspberry, respectively.

Differences in yolk color were observed between the CO and groups BC and RA, as well as between groups CA and BC (P < 0.001). The eggs of group RA were characterized by a lower weight (P = 0.001 and P = 0.002) and shell density (P = 0.025 and P = 0.002) in comparison to eggs from the control group CO. The lightest yolk color was observed in the eggs of group BC in comparison with the other groups (P = 0.006). The greatest yolk weight was observed for group CH, while the smallest was for group CO (P = 0.017). Laying hens in the groups BC and RA were characterized at wk 62 of age by a higher percentage of spleen in comparison with the control group CO (P = 0.018).

In conclusion, the BC and RA diet resulted in a paler yolk color and was associated with slightly poorer shell quality parameters. On the other hand, the CH and BC diet had a positive impact on the immune system of the laying hens, as confirmed by the changes in the white blood cell smear and the higher spleen percentage. Therefore, the use of these by-products in the diets of poultry, i.e., dried pomace of black chokeberry and black currant may have a positive impact by improving the immunological status of laying hens.

Effects of Replacing Inorganic with Organic Iron on Performance, Egg Quality, Serum and Egg Yolk Lipids, Antioxidant Status, and Iron Accumulation in Eggs of Laying Hens

This study compared the effects dietary organic (ferrous glycine [FG]) versus inorganic (ferrous sulfate [FS]) iron in laying hens on performance, egg quality, serum and egg yolk lipids, antioxidant status, and iron enrichment of eggs. A total of 378 Shaver White layers were allotted to 7 treatments with 6 replicates (9 birds each) from 30 to 42 weeks of age. A basal diet (19 mg iron/kg) served as control, while the other six diets were supplemented with either FS or FG to provide 30, 60, and 120 mg/kg of added iron. Dietary FG and FS treatments improved (P < 0.05) laying rate, egg weight, and egg quality of layers, relative to the control, albeit eggshell strength and eggshell calcium also deteriorated with the highest level of FS (P < 0.05). The iron treatment groups exhibited a lower serum and egg yolk levels of triglycerides, total cholesterol, and low-density lipoprotein cholesterol that accompanied by higher levels of high-density lipoprotein cholesterol and greater activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx) as compared with the control (P < 0.05). The contents of malondialdehyde and protein carbonyl were conversely related to the activities SOD and GPx (P < 0.05). The serum and egg fractions (yolk, albumen, and shell) displayed gradually increases in iron contents as the level of iron increased in the diet (P < 0.05), while FG was superior to FS at all tested levels (P < 0.05). To summary, FS can be replaced by FG, with more favorable impacts on egg quality and iron enrichment.

Discriminant Canonical Analysis as a Validation Tool for Multivariety Native Breed Egg Commercial Quality Classification

This study aimed to develop a tool to validate multivariety breed egg quality classification depending on quality-related internal and external traits using a discriminant canonical analysis approach. A flock of 60 Utrerana hens (Franciscan, White, Black, and Partridge) and a control group of 10 Leghorn hens were placed in individual cages to follow the traceability of the eggs and perform an individual internal and external quality assessment. Egg groups were determined depending on their commercial size (S, M, L, and XL), laying hen breed, and variety. Egg weight, major diameter, minor diameter, shell b*, albumen height, and the presence or absence of visual defects in yolk and/or albumen showed multicollinearity problems (variance inflation factor (VIF) > 5) and were discarded. Albumen weight, eggshell weight, and yolk weight were the most responsible traits for the differences among egg quality categories (Wilks’ lambda: 0.335, 0.539, and 0.566 for albumen weight, eggshell weight, and yolk weight, respectively). The combination of traits in the first two dimensions explained 55.02% and 20.62% variability among groups, respectively. Shared properties between Partridge and Franciscan varieties may stem from their eggs presenting heavier yolks and slightly lower weights, while White Utrerana and Leghorn hens’ similarities may be ascribed to hybridization reminiscences.

Genome-Wide Association Study-Based Identification of SNPs and Haplotypes Associated With Goose Reproductive Performance and Egg Quality

Geese are one of the most economically important waterfowl. However, the low reproductive performance and egg quality of geese hinder the development of the goose industry. The identification and application of genetic markers may improve the accuracy of beneficial trait selection. To identify the genetic markers associated with goose reproductive performance and egg quality traits, we performed a genome-wide association study (GWAS) for body weight at birth (BBW), the number of eggs at 48 weeks of age (EN48), the number of eggs at 60 weeks of age (EN60) and egg yolk color (EYC). The GWAS acquired 2.896 Tb of raw sequencing data with an average depth of 12.44× and identified 9,279,339 SNPs. The results of GWAS showed that 26 SNPs were significantly associated with BBW, EN48, EN60, and EYC. Moreover, five of these SNPs significantly associated with EN48 and EN60 were in a haplotype block on chromosome 35 from 4,512,855 to 4,541,709 bp, oriented to TMEM161A and another five SNPs significantly correlated to EYC were constructed in haplotype block on chromosome 5 from 21,069,009 to 21,363,580, which annotated by TMEM161A, CALCR, TFPI2, and GLP1R. Those genes were enriched in epidermal growth factor-activated receptor activity, regulation of epidermal growth factor receptor signaling pathway. The SNPs, haplotype markers, and candidate genes identified in this study can be used to improve the accuracy of marker-assisted selection for the reproductive performance and egg quality traits of geese. In addition, the candidate genes significantly associated with these traits may provide a foundation for better understanding the mechanisms underlying reproduction and egg quality in geese.

Sustainability and Quality Aspects of Different Table Egg Production Systems: A Literature Review

Eggs are of considerable importance in feeding the population, as they are a relatively inexpensive and complex food source of very high biological value. The daily animal protein requirement for the human body can be covered with eggs in the cheapest way and with the lowest environmental impact. As animal welfare, as well as environmental and health awareness issues, become increasingly prominent in developed countries, consumer demand for eggs has also changed significantly in recent years, with an increasing number of consumers buying eggs produced in non-cage housing systems. In recent years, cage housing has been more frequently debated in EU member states. An initiative was launched in 2018 to end cage housing technologies and the sale of eggs produced in this way. However, in addition to animal welfare, a number of other factors need to be considered in relation to sustainable production. For this reason, the aim of this research is to provide a comprehensive overview of the sustainability issues of various housing technologies, as well as quality factors affecting consumer health and egg consumption based on the relevant international references and databases. Although there is a growing demand for products produced in non-cage housing systems due to the increasing relevance of environmental protection, health awareness and animal welfare issues in Western societies, research has shown that non-caged production is not the best solution for environmentally, socially and economically sustainable egg production.

Effect of Dietary Zinc Level on Egg Production Performance and Eggshell Quality Characteristics in Laying Duck Breeders in Furnished Cage System

In order to investigate the effect of dietary Zn levels on laying performance, eggshell quality, and eggshell microstructure in Muscovy duck breeders under furnished cages. Firstly, the effects of age (35 weeks vs 40 weeks) and rearing system (littered floor vs furnished cage) on eggshell quality of laying duck breeders were studied (Exp. 1). Then, a total of 324 30-week-old Muscovy duck breeders were allotted into 3 dietary Zn groups with 6 replicates (18 ducks per replicate), including 0 mg Zn/kg (control-Zn group, C-Zn), 40 mg Zn/kg (normal-Zn group, N-Zn), and 140 mg Zn/kg (high-Zn group, H-Zn). The experimental period for 6 weeks was divided into 3 periods of 30-32, 32-34, and 34-36 weeks of age (Exp. 2). In Exp. 1, duck breeder eggs in the furnished cage system had lower the average shell thickness than birds in the littered floor system at 40 weeks of age (P < 0.05), not at 35 weeks of age. In Exp. 2, N-Zn and H-Zn groups had greater egg weight, egg production, and egg to feed ratio of duck breeders than C-Zn group (P < 0.05). Additionally, H-Zn group had higher laying rate, qualified egg ratio, and Haugh unit as well as lower mammillary cone width than C-Zn group (P < 0.05), with no differences between C-Zn and N-Zn groups (P > 0.05). Diet supplemented with 140 mg Zn/kg increased shell thickness and palisade layer thickness of duck breeders at 36 weeks of age (P < 0.05), but not at 32 and 34 weeks of age. In conclusion, diets with 40 or 140 mg Zn/kg improved egg production performance and egg quality of laying duck breeders during 30-36 weeks of age in a furnished cage system. Dietary supplementation of 140 mg Zn/kg level increased the ultrastructural palisade layer thickness contributing to greater eggshell thickness of duck breeders at 36 weeks of age.

Effect of Breed and Diet Type on the Freshness and Quality of the Eggs: A Comparison between Mos (Indigenous Galician Breed) and Isa Brown Hens

Eggs are a nutritious food, offering a balanced source of essential amino and fatty acids, minerals, and vitamins. Genetic and diet factors can modify hen egg traits. Thus, the effects of breed and feed on egg quality using two laying hens, Mos (autochthonous breed) and Isa Brown (commercial hybrid), and three feeds, commercial fodder (CF), corn/pea/triticale (CPT) and corn/wheat (CW), were investigated. Freshness parameters (egg weight, eggshell weight and thickness, albumen height, Haugh units and yolk color), chemical composition, color and textural parameters, as well as fatty acid profile, were assessed on a total of 288 eggs, from the two breeds. The samples were divided in 96 eggs, corresponding to each of the three dietary treatments. There were significant differences (p < 0.001) in albumen height and Haugh units, obtaining the highest values for Isa Brown genotype; meanwhile, laying hens fed with CF had the highest weight, as well as the greatest eggshell thickness. Cooked yolks of Isa Brown eggs presented the highest values of luminosity, while the yellowness was higher for Mos eggs. Regarding the texture of eggs, genotype was again the parameter having the greatest impact, obtaining higher values in hardness, gumminess and chewiness in those eggs from the Mos breed. Concerning egg chemical composition, it was affected by breed and diet type, but Mos eggs were characterized by a significantly (p < 0.001) higher contents of fat (9.53% vs. 7.58%), protein (12.31% vs. 11.66%) and ash (1.10% vs. 1.04%) than Isa Brown ones. Finally, diet type influenced the fatty acid profile, mainly affecting oleic and linoleic acids, which showed significantly (p < 0.05) highest values (42.90 and 14.66 g/100 g of total fatty acids) in CW and CF diets, respectively. Overall, breed and bird diet factors had a strong effect on egg quality and nutritional profile. Moreover, eggs from Mos hens had more attractive nutritional indices, and they could even be improved more by changing the diet.