Functional connections between bird eggshell stiffness and nest characteristics through risk of egg collision in nests.

Eggs and nests are two critical traits for the ecological success of birds. Their functional interactions, however, remain unclear. Here, we examined the functional connections between egg stiffness and nest attachment, site and structure for 1350 avian species. We revealed high eggshell stiffness for eggs in nests with a pensile attachment, located on non-tree vegetation or having a domed shape, suggesting that birds produce stiffer eggs in response to higher egg-collision risk in unstable or enclosed nests. Interdependence models suggested that the evolution of eggshell stiffness was more likely to be driven by than drive that of nest characters. Our results implied a trade-off between investment in competing for established nesting niches and producing stiff eggs to explore novel niches with high collision risk, possibly mediated by predation or thermoregulation. This study highlights an overlooked connection between nests and eggshells that may have broadened the ecological niches of birds.

How to build a puncture- and breakage-resistant eggshell? Mechanical and structural analyses of avian brood parasites and their hosts.

Evolved eggshell strength is greater in several lineages of obligate avian brood parasites (birds that lay their eggs in other species' nests) than in their hosts. Greater strength is typically indirectly implied by eggshell thickness comparisons between parasites and hosts. Nevertheless, there is strong evidence that the eggshell structural organization differentially influences its mechanical properties. Using instrumental puncture tests and SEM/EBSD and XRD techniques, we studied the most relevant eggshell mechanical, textural, ultrastructural and microstructural features between several host species and their parasitic cowbirds (Molothrus spp.). These parasitic species display different egg-destructive behaviors, reducing host reproductive fitness, including the more frequently host-egg puncturing M. rufoaxillaris and M. bonariensis, and the host egg-removing M. ater. The results, analyzed using a phylogenetic comparative approach, showed interspecific patterns in the mechanical and structural features. Overall, the eggshells of the two egg-puncturing parasites (but not of M. ater) were stronger, stiffer and required greater stress to produce a fracture than the respective hosts' eggs. These features were affected by eggshell microstructure and ultrastructure, related to the increase in the intercrystalline boundary network acting in cooperation with the increase in palisade layer thickness. Both structural features generate more options and greater lengths of intercrystalline paths, increasing the energy consumed in crack or fissure propagation. The reported patterns of all these diverse eggshell features support a new set of interpretations, confirming several hypotheses regarding the impact of the two reproductive strategies (parasitic versus parental) and parasitic egg destruction behaviors (more versus less frequently puncturing).

Tri-ortho-cresyl phosphate exposure leads to low egg production and poor eggshell quality via disrupting follicular development and shell gland function in laying hens.

Tri-ortho-cresyl phosphate (TOCP) has been used commercially as a plasticizer and a flame retardant, which has been reported to cause multiple toxicities in humans and other animals. However, the effect of TOCP on female reproductive system is still unclear. The aim of this investigation was to evaluate the reproductive toxicity of TOCP in female avian and investigate its molecular mechanism. In the current study, 50 adult hens were given a single oral dose of TOCP (750 mg/kg). Egg laid by the hens were harvested and counted. Egg quality is assessed by determining the shell strength and thickness. Samples of ovary, shell gland, and serum were collected on day 0, 2, 7, and 21 after the administration. The morphological and pathological changes in tissues were examined. Cell death, follicular development, and steroidogenesis were determined to assess the toxicity of TOCP on laying hens. The results showed that egg production, egg weight, and eggshell strength significantly decreased after TOCP exposure. The calcium levels in serum and eggshell decreased and the expression levels of the eggshell formation-related genes calbindin-D28k (CaBP-D28k) and carbonic anhydrase 2 (CA2) were downregulated. The inhibitory effects of TOCP on follicular development and steroidogenesis were observed with changes in the levels of the related proteins such as forkhead box O1 (FoxO1) and mothers against decapentaplegic homolog 2/3 (Smad2/3). Cell death was identified, which might lead to follicular development disorder. Taken together, TOCP reduced the quantity and quality of the eggs laid by the hens through disrupting follicular development, steroidogenesis, and shell gland function.

Effects of Dietary Calcium Levels on Productive Performance, Eggshell Quality and Overall Calcium Status in Aged Laying Hens.

This study was conducted to investigate the effects of diets with varying levels of calcium on egg production, shell quality and overall calcium status in aged laying hens. A total of five hundred 70-wk-old Hy-Line Brown layers were divided five groups and fed one of the five experimental diets with 3.5%, 3.8%, 4.1%, 4.4%, or 4.7% Ca, for 10 weeks. There were no significant differences in feed intake, egg production and egg weight among groups. The cracked eggs were linearly reduced as dietary Ca levels increased to 4.7% (p<0.01). A significant linear improvement for eggshell strength and thickness were determined with increasing dietary Ca levels (p<0.01). The contents of serum Ca and phosphorus were not affected by dietary Ca levels. With increase in dietary Ca levels, the tibial breaking strength slightly increased. There were no significant differences in the tibial contents of ash, Ca and phosphorus among groups. In conclusion, eggshell quality, as measured by appearance, strength and thickness of eggshell, were influenced by dietary Ca content as expected (p<0.05). These results suggested that aged laying hens require relatively higher level of Ca than required levels from current Korean feeding standards for poultry.

The effect of eggshell apex abnormalities on table egg quality during storage in 2 seasons of the year.

Mycoplasma synoviae infection of hens has been associated with problems of eggshell quality called eggshell apex abnormalities (EAA). Little is known about the quality of EAA eggs from a commercial point of view, especially during their storage. The study aimed to examine the differences between EAA and normal eggs during storage under controlled conditions in 2 seasons, summer and winter, by comparing internal and external quality parameters. In a conventional egg production farm with white laying hens of varying ages in the city of Bastos, state of São Paulo, Brazil, 232 eggs were used in the summer season and 400 eggs in the winter season. Half of the eggs had EAA, and the other half were considered normal eggs for each season. The eggs were analyzed at 2, 7, 14, 21, and 28 d after being laid and stored from 24.6 to 25.8°C in summer and from 24 to 25°C in winter. There was no difference (P > 0.05) in the average egg weight between EAA and normal eggs at any studied time point, but in both seasons, the weight loss in EAA eggs was higher than in normal eggs. The losses in Haugh unit scores from the first to the last measurements were approximately 40% regardless of egg type or season of production. In comparing eggshell thickness, only the apices of the EAA eggs were thinner (P < 0.0001) than normal eggs in the summer, but in the winter, the EAA egg apices (P < 0.0001) and sides (P = 0.03) were both thinner. The presence of EAA did not affect the eggshell weight (P > 0.05) or eggshell percentage (P > 0.05). The eggshell strength of the EAA eggs was lower (P < 0.0001) than normal eggs in both the summer (16.57%) and winter (19.86%). The presence of EAA did not affect the internal quality of the egg, but was related to a greater loss of external quality and weight during storage.

Comparative Analysis of the Ultrastructure, Bubble Pores, and Composition of Eggshells of Dwarf Layer-White and Guinea Fowl.

The decrease in eggshell quality seriously affects production efficiency. Guinea fowl (GF) eggs possess strong eggshells because of their unique crystal structure, and few systematic studies have compared laying hen and GF eggs. Sixty eggs were collected from both 40-week-old Dwarf Layer-White (DWL-White) laying hens and GF, and the eggshell quality, ultrastructure, bubble pores, and composition were measured. The results showed that the DWL-White eggs had a higher egg weight and a lower eggshell strength, strength per unit weight, thickness, and ratio than the GF eggs (p < 0.01). There were differences in the mammillary layer thickness ratio, the effective layer thickness ratio, the quantity of bubble pores (QBPs), the ratio of the sum of the area of bubble pores to the area of the eggshell in each image (ARBE), and the average area of bubble pores (AABPs) between the DWL-White and GF eggs (p < 0.01). The composition analysis demonstrated that there were differences in the organic matter, inorganic matter, calcium, and phosphorus between the DWL-White and GF eggs (p < 0.01). There were positive associations between the mammillary knob number in the image and the QBPs and ARBE and a negative correlation with the AABPs in the DWL-White eggs (p < 0.01). This study observed distinctions that offer new insights into enhancing eggshell quality.

Differential label-free quantitative proteomic analysis of avian eggshell matrix and uterine fluid proteins associated with eggshell mechanical property.

Eggshell strength is a crucial economic trait for table egg production. During the process of eggshell formation, uncalcified eggs are bathed in uterine fluid that plays regulatory roles in eggshell calcification. In this study, a label-free MS-based protein quantification technology was used to detect differences in protein abundance between eggshell matrix from strong and weak eggs (shell matrix protein from strong eggshells and shell matrix protein from weak eggshells) and between the corresponding uterine fluids bathing strong and weak eggs (uterine fluid bathing strong eggs and uterine fluid bathing weak eggs) in a chicken population. Here, we reported the first global proteomic analysis of uterine fluid. A total of 577 and 466 proteins were identified in uterine fluid and eggshell matrix, respectively. Of 447 identified proteins in uterine fluid bathing strong eggs, up to 357 (80%) proteins were in common with proteins in uterine fluid bathing weak eggs. Similarly, up to 83% (328/396) of the proteins in shell matrix protein from strong eggshells were in common with the proteins in shell matrix protein from weak eggshells. The large amount of common proteins indicated that the difference in protein abundance should play essential roles in influencing eggshell strength. Ultimately, 15 proteins mainly relating to eggshell matrix specific proteins, calcium binding and transportation, protein folding and sorting, bone development or diseases, and thyroid hormone activity were considered to have closer association with the formation of strong eggshell.

Microarray analysis of genes involved with shell strength in layer shell gland at the early stage of active calcification.

The objective of this study was to get a comprehensive understanding of how genes in chicken shell gland modulate eggshell strength at the early stage of active calcification. Four 32-week old of purebred Xianju hens with consistent high or low shell breakage strength were grouped into two pairs. Using Affymetrix Chicken Array, a whole-transcriptome analysis was performed on hen's shell gland at 9 h post oviposition. Gene ontology enrichment analysis for differentially expressed (DE) transcripts was performed using the web-based GOEAST, and the validation of DE-transcripts was tested by qRT-PCR. 1,195 DE-transcripts, corresponding to 941 unique genes were identified in hens with strong eggshell compared to weak shell hens. According to gene ontology annotations, there are 77 DE-transcripts encoding ion transporters and secreted extracellular matrix proteins, and at least 26 DE-transcripts related to carbohydrate metabolism or post-translation glycosylation modification; furthermore, there are 88 signaling DE-transcripts. GO term enrichment analysis suggests that some DE-transcripts mediate reproductive hormones or neurotransmitters to affect eggshell quality through a complex suite of biophysical processes. These results reveal some candidate genes involved with eggshell strength at the early stage of active calcification which may facilitate our understanding of regulating mechanisms of eggshell quality.

Transcriptomic analysis of the liver in aged laying hens with different eggshell strength.

Eggshell is composed of a very ordered and mineralized structure and is important for egg quality. Eggshell strength is particularly important because of its direct association with economic outcomes and egg safety. Various factors related to laying hens and their environment affects eggshell strength. However, the molecular mechanisms of liver functions related to decreased eggshell strength of aged laying hens are largely unknown. Therefore, this study aimed to identify potential factors affecting eggshell strength in aged laying hens at the hepatic transcriptomic level. A total of five hundred 92-wk-old Hy-line Brown laying hens were screened to select those exhibiting the greatest variation in eggshell strength. Based on the final eggshell strength, 12 hens producing eggs with strong eggshell strength (SES) and weak eggshell strength (WES) were finally selected (n = 6) for liver tissue sampling. The RNA-sequencing was performed to identify differentially expressed genes (DEGs) between the 2 groups. We identified a total of 2,084 DEGs, of which 1,358 genes were upregulated and 726 genes were downregulated in the WES group compared with SES group. According to the Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis, the DEGs indicated the mammalian target of rapamycin signaling pathway, the Janus kinase-signal transducer and activator of transcription pathway, the mitogen­activated protein kinase signaling pathway, and the insulin resistance pathways. Genes related to fatty liver disease were upregulated in WES group compared with SES group. In addition, expression of several genes associated with oxidative stress and bone resorption activity was altered in aged laying hens with different eggshell strength. Overall, these findings contribute to the identification of genes involved in different intensity of eggshell strength, enabling more understanding of the hepatic molecular mechanism underlying in decreased eggshell strength of aged laying hens.

Non-Destructive Eggshell Strength Assessment Using Hertz Contact Theory-Part II: Implementation and Validation.

Eggshell strength is a critical quality factor for consumption eggs as it affects the probability of breakage in practice. In this study, a fast and low-cost methodology for the non-destructive determination of eggshell strength is presented. The method utilized a small steel ball to impact the egg and a microphone to analyse the impact characteristics. Hertz contact theory was applied to relate the measured impact characteristics to the local stiffness of the eggshell. Therefore, a total of 150 eggs were studied on which eight consecutive measurements per egg were taken around the equator at equidistant places. The results showed a strong correlation of 0.93 between the traditional static stiffness measured during quasi-static compression tests and the average stiffness obtained from the new methodology. This paves the way towards fast, low-cost and non-destructive in-line shell strength measurements to reduce the number of cracked eggs reaching the consumer.

Non-Destructive Eggshell Strength Assessment Using Hertz Contact Theory Part I: Theory and Applicability.

In the egg industry, fast and highly reliable quality measurements are crucial. This study presents a novel method based on Hertz contact theory that allows for non-destructive determination of eggshell strength. The goal of the study was to evaluate the material strength (Young's Modulus) and structural strength (stiffness) of eggshells. To this end, an experimental setup was constructed to measure the collision of an eggshell with a small steel ball, which was recorded using a laser vibrometer. The study analyzed a sample of 120 eggs and found a correlation of 0.85 between the traditional static stiffness measured during quasi-static compression tests and the stiffness obtained from the Hertz contact theory. The results show that Hertz contact theory is valid for small steel spheres impacting eggshells, while a sensitivity analysis indicated that the most important factor in determining the strength of the eggshell is the contact duration between the egg and the impactor. These results open up the possibility of grading eggs based on their shell strength in a non-destructive manner.

Effect of Organic or Inorganic Mineral Premix in the Diet on Laying Performance of Aged Laying Hens and Eggshell Quality.

In this study, we examined the effect of diets supplemented with organic and inorganic mineral premixes on the laying performance and eggshell quality of aged laying hens. A total of 600 68-week-old Hy-Line Brown laying hens were randomly assigned to 1 of 3 dietary treatments, repeated 5 times: Mash type basal diet, basal diet supplemented with an inorganic mineral premix (1.0 g/kg), and basal diet supplemented with an organic mineral premix (1.8 g/kg). The results showed that eggshell strength was higher (p < 0.01) in the inorganic mineral diet group than in the organic mineral and basal diet groups. Further, the levels of Fe and Mn in the liver were higher (p < 0.05) in the inorganic and organic mineral diet groups than in the basal diet group. The concentrations of Fe and Mg in the spleen were different (p < 0.05) among the treatment groups, with the highest levels reported in the organic mineral premix group. The concentrations of Cu, Zn, and Mn in the eggshell were different (p < 0.05) among the groups, with the highest levels reported in the inorganic and organic mineral premix diet groups. In conclusion, a diet containing organic mineral premix improved eggshell strength and had no detrimental effect on the laying performance of aged laying hens.

Probiotic Bacillus subtilis C-3102 Improves Eggshell Quality after Forced Molting in Aged Laying Hens.

This study was carried out to evaluate the effects of probiotic Bacillus subtilis C-3102 feed additive on quality characteristics including strength, thickness, and weight of eggshells of Boris Brown laying hens. The control group (n=64) was fed a basal diet comprised of maize and feed rice, whereas the experimental group (n=64) was fed a basal diet supplemented with B. subtilis C-3102 (3×105 CFU/g) starting at 49 weeks of age. From 67 to 69 weeks, all hens were induced to molt using an anorexic program; then, the birds in both groups returned to their respective diets (from 69 to 82 weeks). Eggshell strength, measured six times with 60 eggs selected before the molting treatment, was significantly greater in the C-3102 group than in the control group at 51, 59, 63, and 66 weeks (3.45, 3.44, 3.28, and 3.13 kg/cm2; P<0.05, 0.05, 0.01, and 0.01, respectively). Moreover, eggshell strength-measured three times after the molting treatment-was significantly greater in the C-3102 group than in the control group at 73 and 77 weeks (3.79 and 3.65 kg/cm2; P<0.01 and 0.01, respectively). Eggshell thickness was also significantly greater in the C-3102 group than in the control group at 73 and 77 weeks (0.400 and 0.390 mm; P<0.01 and 0.01, respectively). Fecal samples collected from eight hens of each group at 70 weeks of age after forced molting, showed a significantly higher proportion of Lactobacillus spp. in the C-3102 group (8.94 log CFU/g) (P<0.05) than in the control group (8.63 log CFU/g). Clostridium spp. abundance was significantly lower in the C-3102 group (2.92 log CFU/g) than in the control group (4.3 log CFU/g). These results suggest that C-3102 supplementation improves eggshell quality in aged laying hens, particularly after forced molting.

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.

Identification of Age-Specific and Common Key Regulatory Mechanisms Governing Eggshell Strength in Chicken Using Random Forests.

In today's chicken egg industry, maintaining the strength of eggshells in longer laying cycles is pivotal for improving the persistency of egg laying. Eggshell development and mineralization underlie a complex regulatory interplay of various proteins and signaling cascades involving multiple organ systems. Understanding the regulatory mechanisms influencing this dynamic trait over time is imperative, yet scarce. To investigate the temporal changes in the signaling cascades, we considered eggshell strength at two different time points during the egg production cycle and studied the genotype-phenotype associations by employing the Random Forests algorithm on chicken genotypic data. For the analysis of corresponding genes, we adopted a well established systems biology approach to delineate gene regulatory pathways and master regulators underlying this important trait. Our results indicate that, while some of the master regulators (Slc22a1 and Sox11) and pathways are common at different laying stages of chicken, others (e.g., Scn11a, St8sia2, or the TGF- ß pathway) represent age-specific functions. Overall, our results provide: (i) significant insights into age-specific and common molecular mechanisms underlying the regulation of eggshell strength; and (ii) new breeding targets to improve the eggshell quality during the later stages of the chicken production cycle.

Combining Random Forests and a Signal Detection Method Leads to the Robust Detection of Genotype-Phenotype Associations.

Genome wide association studies (GWAS) are a well established methodology to identify genomic variants and genes that are responsible for traits of interest in all branches of the life sciences. Despite the long time this methodology has had to mature the reliable detection of genotype-phenotype associations is still a challenge for many quantitative traits mainly because of the large number of genomic loci with weak individual effects on the trait under investigation. Thus, it can be hypothesized that many genomic variants that have a small, however real, effect remain unnoticed in many GWAS approaches. Here, we propose a two-step procedure to address this problem. In a first step, cubic splines are fitted to the test statistic values and genomic regions with spline-peaks that are higher than expected by chance are considered as quantitative trait loci (QTL). Then the SNPs in these QTLs are prioritized with respect to the strength of their association with the phenotype using a Random Forests approach. As a case study, we apply our procedure to real data sets and find trustworthy numbers of, partially novel, genomic variants and genes involved in various egg quality traits.

Long-term selection using a single trait criterion, non-destructive deformation, in White Leghorns: Effect over time on genetic parameters for traits related to egg production.

Although non-destructive deformation is relevant for assessing eggshell strength, few long-term selection experiments are documented which use non-destructive deformation as a selection criterion. This study used restricted maximum likelihood-based methods with a four-trait animal model to analyze the effect of non-destructive deformation on egg production, egg weight and sexual maturity in a two-way selection experiment involving 17 generations of White Leghorns. In the strong shell line, corresponding to the line selected for low non-destructive deformation values, the heritability estimates were 0.496 for non-destructive deformation, 0.253 for egg production, 0.660 for egg weight and 0.446 for sexual maturity. In the weak shell line, corresponding to the line selected for high non-destructive deformation values, the heritabilities were 0.372, 0.162, 0.703 and 0.404, respectively. An asymmetric response to selection was observed for non-destructive deformation, egg production and sexual maturity, whereas egg weight decreased for both lines. Using non-destructive deformation to select for stronger eggshell had a small negative effect on egg production and sexual maturity, suggesting the need for breeding programs to balance selection between eggshell traits and egg production traits. However, the analysis of the genetic correlation between non-destructive deformation and egg weight revealed that large eggs are not associated with poor eggshell quality.

Traits of eggshells and shell membranes of translucent eggs.

Translucent eggshells negatively affect the appearance of eggs and decrease their economic value. Translocation and accumulation of water from the contents to the shells of eggs are frequent occurrences. Causes of translucent eggshell formation have been investigated, but the primary reason is uncertain. In previous studies, scientists have found that the thickness of the eggshell membrane was significantly different between translucent and opaque eggs. However, there are some conflicts among studies. We performed 2 experiments with 3 breeding flocks of chickens to target the reasons for egg translucence. In experiment 1, eggs of 1,024 Brown-Egg Dwarf Layers (DWL) were used. Approximately 1,600 eggs were collected over 2 consecutive days. They were stored for 3 days, and then 120 translucent and 120 opaque eggs were selected for measurement of egg quality traits and weight loss over several weeks. In experiment 2, we used DWL and White Leghorn pure line (WLL) for assessment of eggshell ultrastructure and membrane traits. We chose 120 translucent and 120 opaque eggs from 3,500 DWL eggs and 125 translucent and 125 opaque eggs from 5,028 WLL eggs. The results are as follows: (1) translucent eggs had greater eggshell strength and lower ultimate failure stress of shell membrane than opaque eggs in both DWL and WLL groups, (2) translucent eggs had thicker shells and thinner shell membranes than opaque eggs in DWL, (3) no significant differences were found in either gas pore or bubble pore traits between translucent and opaque eggs in either line, and (4) no significant differences were detected in internal egg quality or weight loss between translucent and opaque eggs in either line. In summary, the present study suggests that variations in both eggshells and shell membrane structures are implicated in the formation of translucent eggs.

Environment type and storage period on eggshell quality of laying hens at different ages / Tipos de ambiente e período de armazenamento sobre a qualidade de casca de ovos de poedeiras comerciais em diferentes idades

ABSTRACT: Eggshell quality is directly linked to the good acceptability of the product by consumers, whereas the industry is concerned with economic losses. Prolonged periods of laying, diseases, nutrition, bird age and genetics can influence egg quality. This study aimed to examine the influence of the environment, bird age and storage period on the physical characteristics of the shell of eggs from commercial laying hens. The experiment involved 288 eggs from Hy-line hens, which were distributed in a completely randomized design with a triple 3×2×4 factorial arrangement represented by three ages (31, 62 or 88 weeks), two storage temperatures (ambient or refrigerated), and four storage periods (one, 10, 20 or 30 days), totaling 24 treatments. Four replications were used with three eggs each. Eggshell strength, percentage and thickness were measured. Differences were observed, with the eggs stored at room temperature exhibiting lower shell strength. Laying eggs at an advanced age (88 weeks) resulted in decreased eggshell strength as compared with the other ages, whereas the eggs from young layers (31 weeks) had a thicker shell. The advancing age of the laying hens reduced eggshell quality, regardless of the storage environment. Nonetheless, the eggs stored in the refrigerator showed better eggshell quality and integrity than those stored at ambient temperature.

RESUMO: A qualidade da casca está diretamente ligada à boa aceitabilidade do produto pelos consumidores, enquanto a indústria se preocupa com as perdas econômicas. Períodos prolongados de postura, doenças, nutrição, idade da ave e genética podem influenciar a qualidade dos ovos. Objetivou-se avaliar a influência do ambiente, idade da ave e período de armazenamento nas características físicas da casca de ovos de poedeiras comerciais. Foram utilizados 288 ovos de poedeiras Hy-line, distribuídos em um delineamento inteiramente casualizado em fatorial triplo 3x2x4, sendo os fatores: três idades (31, 62 e 88 semanas), temperatura de armazenamento (ambiente e refrigerado), e quatro períodos de armazenamento (um, 10, 20 e 30 dias), totalizando 24 tratamentos, com quatro repetições de três ovos. Avaliou-se a resistência, percentual e espessura da casca. Foram observadas diferenças, uma vez que os ovos armazenados em temperatura ambiente apresentaram diminuição na resistência de casca. Ovos de poedeiras em idade avançada (88 semanas) apresentaram pior resistência de casca em relação às demais idades, enquanto ovos provenientes de poedeiras jovens (31 semanas) apresentaram maior espessura de casca. A idade avançada da poedeira reduziu a qualidade de casca dos ovos, independentemente do ambiente de armazenamento. Ainda, os ovos armazenados em geladeira apresentaram melhor qualidade e integridade da casca em comparação com os armazenados ao ambiente.