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This study presents the results of a dynamic two-point bending test and a quasi-static three-point bending test of the quail femurs. Bones from females and males of two genetic strains of Japanese quail belonging to various utility types were analyzed. Mechanical parameters obtained under impact and quasi-static loading conditions were investigated. The mechanical strength of eggshells under both loading conditions was also examined. The obtained results showed that the bones of males of both analyzed types of quails were characterized by statistically significant higher strength obtained under impact loading conditions compared to the bones of females. Moreover, the mechanical strength of the eggshell measured under impact loading conditions was characterized by higher values compared to the result obtained under quasi-static load conditions. The observed differences between quail genetic lines were not statistically significant. SEM-EDS qualitative elemental distribution analysis showed a higher content of calcium in the female femurs. The damage present on the fracture surface indicates that these bones were more brittle. [ABSTRACT FROM AUTHOR]

Clanis bilineata is a nutritious and edible insect. In this study, the effects of dietary C. bilineata larva meal (CBLM) on laying performance, egg quality, and serum biochemical parameters of aged laying hens were investigated. A trial diet was formulated by replacing soybean meal with CBLM in the basic diet of laying hens, whereas the basic diet served as a control. Results showed that compared with the control, dietary CBLM increased day egg production, egg weight, egg mass, food intake, yolk colour, eggshell strength, yolk linolenic acid content, yolk total polyunsaturated fatty acid content, superoxide dismutase activity, glutathione peroxidase activity, catalase activity, acid phosphatase activity, alkaline phosphatase activity, glutamyl transpeptidase, activity, and high-density lipoprotein level. Conversely, dietary CBLM decreased the feed-conversion ratio, oleic acid, linoleic acid, and monounsaturated fatty acid in yolks, as well as serum malondialdehyde, total cholesterol, triglycerides, and low-density lipoprotein cholesterol levels. These findings indicated that dietary CBML can ameliorate the laying performance, egg quality, and health status of aged laying hens. [ABSTRACT FROM AUTHOR]

Simple Summary: A decrease in eggshell quality in the late laying period leads to eggshell breakage, seriously affecting production efficiency. Guinea fowl with relatively high eggshell strength have the same layers of eggshell structure and various identical proteins as laying hens. However, their eggshell structures have not been systematically compared. Therefore, this study systematically compared the eggshell ultrastructure, bubble pore index, and composition of laying hens and Guinea fowl. The differences in the eggshell ultrastructure, bubble pores, and composition revealed, to some extent, the structure and composition necessary to increase the eggshell quality of laying hens. This study provides a reference for improving eggshell quality. 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. [ABSTRACT FROM AUTHOR]

ABSTRACT This study aimed to compare the egg quality between the bluish-shelled (BSh) and whitish-shelled (WSh) eggs of Taiwanese Tsaiya ducks. Experiments were conducted to determine eggshell thickness and strength, heat absorption capability, and egg yolk lipid peroxidation. Our results showed that the eggshell thickness and strength of BSh eggs were higher than that of WSh eggs during both the autumn and winter seasons (p

The aim of the study was to determine the calcium requirements in preparation period of the sexual mature and egg-laying and evaluate development of calcium retention in the first laying period of the hybrid combination Bovans Brown hens. The experimental trial lasted from 14 to 30 weeks of hens age. The animals were fed ad libitum with a pelleted complete feed mixture with 42 g/kg of calcium content. The amount of calcium retained by pullets gradually increased along with feed intake depending on age and preparation for sexual maturity and was around 0.39 ± 0.19 g Ca in the first period. Ca retention increased up to an average of 0.85 g Ca from 8 day before laying the first egg. Retention dropped sharply on the day of laying the 1st egg and a negative Ca balance occurred. Shell output was 1.75 ± 0.21 g/day for the beginning of laying and subsequently increased to 2.23 ± 0.08 g/ day during evaluate peak laying. The range weight of the first laid eggs was 45 ± 5 g. Percentage of eggshell move around an average of 10 ± 0.37% throughout the observed period. The daily calcium intake of pullets was 3.56 ± 0.26 g/day. With the beginning of laying, the daily intake increased to an average of 4.51 ± 0.43 g/day Ca. Before reaching sexual maturity, the calcium apparent digestibility of laying hens was relatively low, averaging around 22%, but the moment the hens began to lay, the apparent calcium digestibility began to increase to an average of 50%. Feeding a non-standard feed mixture with a higher calcium content than usual in mixtures for pullets did not have a negative effect on the finishing of animal development, the onset of sexual maturity, or deterioration of the observed parameters of eggs quality.

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.

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The aim of the study was to determine the calcium requirements in preparation period of the sexual mature and egg-laying and evaluate development of calcium retention in the first laying period of the hybrid combination Bovans Brown hens. The experimental trial lasted from 14 to 30 weeks of hens age. The animals were fed ad libitum with a pelleted complete feed mixture with 42 g/kg of calcium content. The amount of calcium retained by pullets gradually increased along with feed intake depending on age and preparation for sexual maturity and was around 0.39 ± 0.19 g Ca in the first period. Ca retention increased up to an average of 0.85 g Ca from 8 day before laying the first egg. Retention dropped sharply on the day of laying the 1st egg and a negative Ca balance occurred. Shell output was 1.75 ± 0.21 g/day for the beginning of laying and subsequently increased to 2.23 ± 0.08 g/day during evaluate peak laying. The range weight of the first laid eggs was 45 ± 5 g. Percentage of eggshell move around an average of 10 ± 0.37% throughout the observed period. The daily calcium intake of pullets was 3.56 ± 0.26 g/day. With the beginning of laying, the daily intake increased to an average of 4.51 ± 0.43 g/day Ca. Before reaching sexual maturity, the calcium apparent digestibility of laying hens was relatively low, averaging around 22%, but the moment the hens began to lay, the apparent calcium digestibility began to increase to an average of 50%. Feeding a non-standard feed mixture with a higher calcium content than usual in mixtures for pullets did not have a negative effect on the finishing of animal development, the onset of sexual maturity, or deterioration of the observed parameters of eggs quality. [ABSTRACT FROM AUTHOR]

ABSTRACT: 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 mitogen‑activated 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.

Hatchability is affected by a variety of factors. Eggshell quality plays very important role among these factors. In this work we analysed eggshell quality, hatchability and embryonic mortality of pure chicken breeds New Hampshire, Oravka, Plymouth Rock, Rhode Island Red and Sussex Light. Hatchability was significantly lower (P>0.05) in Sussex Light in comparison with New Hampshire. The eggshell quality for Sussex Light was significantly decreased (P>0.05) in eggshell thickness (398.73 vs. 356.07 μm) and eggshell percentage compared with New Hampshire (10.36 vs. 8.79 %).

Simple Summary: Organic trace minerals have a greater impact on eggshell quality than inorganic trace minerals. Trace minerals involved in animal growth and development, including eggshell formation, are essential for laying hens. However, most previous research center around the effects of single trace minerals or single aspects of mineral supplementation. The effect of synchronous replacement of inorganic minerals, such as iron, copper, zinc, manganese, and magnesium, with organic trace minerals on the quality of eggs laid by aged laying hens, has not been evaluated extensively. This study concludes that feed with organic trace minerals improved eggshell quality of aged laying hens. 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. [ABSTRACT FROM AUTHOR]

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

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. [ABSTRACT FROM AUTHOR]

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.

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.

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.

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.

Obligate avian brood parasites depend on hosts for parental care, which in turn suffer fitness losses as a result of parasitism. Mechanisms by which brood parasitic cowbirds (Molothrus spp.) reduce host breeding success include the puncture (M. rufoaxillaris and M. bonariensis) or removal (M. ater) of the eggs of the host. Our working hypothesis is that the host eggs' mechanical strength and their size and shape in species with higher frequency of parasitism covaries with the cowbird's strategy to reduce host clutch size. Our results, obtained through phylogenetic analyses based on egg 2D geometric morphometry and eggshell mechanical and ultrastructural measurements, suggest that egg-puncturer behaviour has led to an increase in the strength of the host's eggshell, which might make them more difficult to be pierced. We also characterized larger, more rounded and asymmetrical eggs in frequent hosts of M. ater , which might be more difficult to be removed. These interspecific host egg and shell traits were also positively affected by the frequency of parasitism, indicating that species-specific patterns of parasitic costs select for respective anti-parasitic defences in hosts. [ABSTRACT FROM AUTHOR]

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.

Egg quality and eggshell ultrastructural properties of four Saudi native chicken breeds were compared to detect genetic differences. A total of 480 laying hens at 28 weeks of age, representing four Saudi native breeds of chicken (black, black-barred, gray, and brown) kept under hot environmental conditions (34 ± 1°C) were randomly assigned to the current experiment. Laying hens were housed in individual cages in an open-sided house during hot summer season. A total of 360 intact eggs were randomly collected (90 from each breed) for egg quality assessment. Eggshell samples were prepared to evaluate ultrastructural measurements using a scanning electron microscope. No significant variations between the breeds concerning egg weight, egg-shape index, yolk index, albumen (%), yolk (%), shell (%), and shell thickness traits were detected. Brown breed showed significantly higher Haugh units compared to the other breeds. Moreover, brown breed scored the best for eggshell breaking strength trait (the highest crack resistance), followed by gray, black, and black-barred breeds, respectively (P < 0.005). Total ultrastructural score for mammillary layer measurements was significantly higher in black-barred breed if compared with black, brown, and gray breeds. Gray, brown, and black Saudi native breeds had an outstanding eggshell ultrastructure and, in turn, stiffer and stronger eggshell comparable with black-barred counterpart under high ambient temperatures. At the national level, for cross-breeding and selection programs aimed at producing good quality table and hatching eggs the use of gray, brown, and black breeds can be recommended due to excellent ultrastructural properties of their eggshell.

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-β 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. [ABSTRACT FROM AUTHOR]

The objective of the present study was to determine the relationship between eggshell thickness and other eggshell characteristics in eggs produced in litter housing system and enriched cages. Eggs were collected from 200 birds of ISA Brown genotype at 40–42 weeks of age. Half of the birds were housed in enriched cages (750 cm2/hen, 10 hens/cage) and the other half were housed in littered pens (9 hens/m2, 10 hens/pen). Eggs in each housing system were split into three categories varying in shell thickness: the first category (thin shells 0.28–0.30 mm), the second category (medium shells 0.33–0.36 mm) and the third category (thick shells 0.39–0.41 mm). Results indicated that eggshell parameters differ significantly according to eggshell thickness. Significant interaction of shell category and housing system were observed in eggshell strength. As expected, the eggshell strength was increased with eggshells becoming thicker. Moreover, eggs with the thickest shells from enriched cages had significantly stronger shells than those from litter system. Eggshell weight was significantly increased in the thick eggshell category being higher in enriched cages (7.23 g) than in litter system (5.14 g). The Pearson’s correlation coefficients showed a positive correlation between eggshell parameters and eggshell thickness in both housing systems. Moreover, the correlation between eggshell thickness and eggshell strength was higher on litter (0.64, p

ABSTRACT The present study aimed at evaluating the effects of a coating based on copaiba oil on the quality of eggs stored for different periods. Eggs were coated with copaiba oil solutions (4, 8, 12, 16, or 20% copaiba oil) or not (control) and stored for 1, 7, 14, 21, 28 or 35 days at room temperature. The following parameters were evaluated: egg weight loss, egg components (albumen, yolk, and eggshell) relative weights, egg specific gravity, Haugh units, eggshell quality, and sensorial attributes. Eggs stored for 35 days presented the highest weight losses. Coating (20% copaíba oil solution) reduced egg weight loss up to 41.02%. Coated eggs presented better internal quality (yolk and albumen heights, specific gravity, and eggshell strength). Sensorial attributes were negatively affected by storage time (aroma and flavor), and copaiba oil solution (aroma, appearance, and flavor), with the natural odor of copaiba described by the tasters. Egg internal, external, and sensorial quality worsened with storage time. Solutions containing 16 and 20% copaiba oil can be used as a biofilm to coat eggs, preserving its internal and external quality, and may affect their sensory characteristics, and therefore, may be a viable alternative for maintaining the internal quality of eggs stored at room temperature for long periods.

In order to study the effect of manganese sources in the form of sulphate, hydroxychloride and methionine-chelated manganese organic complex on egg quality of aged laying hens, an experiment was conducted using 384 Hy-line W-36 laying hens at 65 week of age for 8 weeks in completely randomized design with 6 treatments, 4 replications and 16 hens in each replication. The experimental treatments included control (with no Mn supplementation), control plus 50, 70 and 90 mg of Mn as hydroxychloride per kg of diet, control plus 70 mg of manganese as manganesemethionine organic complex per kg of diet and 70 mg of manganese as manganese sulphate per kg of diet. The results showed that the different manganese sources had no significant effect on body weight, feed intake, egg production rate, yolk index, specific gravity and Haugh unit of egg. All treatments had better feed conversion ratio in weeks 6, 8 and in the entire experimental period when compared to control group (P<0.05). All treatments increased egg weight at 8th week and entire experimental period and eggshell thickness, eggshell percentage and eggshell breaking strength during different weeks of experiment when compared to control group (P<0.05). The increase in eggshell strength with 90 mg/kg of manganese hydroxychloride in comparison to 70 mg/kg of manganese sulphate was significant (P<0.05), however no significant difference was observed between 50 mg/kg manganese hydroxychloride and 70 mg/kg manganese-methionine organic complex. The use of manganese organic source or manganese hydroxychloride increased blood and tibia manganese concentrations (P<0.05) in comparison to control group. Generally, the results showed that 50 mg/kg of manganese hydroxychloride can be replaced for 70 mg/kg of manganese-methionine organic complex or manganese sulphate in the diet of aged laying hens. [ABSTRACT FROM AUTHOR]

This paper presents a review describing genetic and phenotypic attributes of eggshell quality traits that are considered worldwide in genetic selection of layers. Eggshell strength plays a key role in production of both table and hatching eggs; hence, breeding companies include quite a variety of traits associated with eggshell strength in their breeding criteria. While the level of eggshell resistance to mechanical damage, as the ultimate manifestation of eggshell strength, can be estimated based on recording of other indicative traits, the eggshell strength itself has got to be negotiated by hatching ease. It appears, however, that space for eggshell strength selection exists as genetic correlations between strength and hatchability are still close to null or even moderately positive. Unfavourable genetic correlations between breaking strength and other economically important traits such as albumen height, and, in particular, egg production and egg weight support the choice of braking strength as the breeding goal component. The most common indirect method of eggshell strength evaluation is specific gravity whereas from the breeder's point of view ultrasonic eggshell thickness measurement should be considered as a good choice selection criterion. [ABSTRACT FROM AUTHOR]

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

The paper deals with the evaluation of the effect of hen breed on the egg response to the non-destructive impact. The eggs of four hen breeds (Leghorn White, Rhode Island Red, Bar Plymouth Rock and Sussex Light) were tested. An experimental system was set up to generate the impact force, measure the response wave signal, and analyse the frequency spectrum in the three direction of loading (sharp end, equator, blunt end). The egg dynamic resonance frequency was obtained through the analysis of the dynamically measured frequency response of an egg excited by light impact of a bar. The results showed that the dominant frequency was significantly affected by the hen bread and not significantly affected by excitation velocity. The dominant frequency enables to estimate the eggshell strength under quasi static compression.

Egg quality and eggshell ultrastructural properties of four Saudi native chicken breeds were compared to detect genetic differences. A total of 480 laying hens at 28 weeks of age, representing four Saudi native breeds of chicken (black, black-barred, gray, and brown) kept under hot environmental conditions (34 ± 1°C) were randomly assigned to the current experiment. Laying hens were housed in individual cages in an open-sided house during hot summer season. A total of 360 intact eggs were randomly collected (90 from each breed) for egg quality assessment. Eggshell samples were prepared to evaluate ultrastructural measurements using a scanning electron microscope. No significant variations between the breeds concerning egg weight, egg-shape index, yolk index, albumen (%), yolk (%), shell (%), and shell thickness traits were detected. Brown breed showed significantly higher Haugh units compared to the other breeds. Moreover, brown breed scored the best for eggshell breaking strength trait (the highest crack resistance), followed by gray, black, and black-barred breeds, respectively (P < 0.005). Total ultrastructural score for mammillary layer measurements was significantly higher in black-barred breed if compared with black, brown, and gray breeds. Gray, brown, and black Saudi native breeds had an outstanding eggshell ultrastructure and, in turn, stiffer and stronger eggshell comparable with black-barred counterpart under high ambient temperatures. At the national level, for cross-breeding and selection programs aimed at producing good quality table and hatching eggs the use of gray, brown, and black breeds can be recommended due to excellent ultrastructural properties of their eggshell. [ABSTRACT FROM AUTHOR]

The objective of the present study was to determine the relationship between eggshell thickness and other eggshell characteristics in eggs produced in litter housing system and enriched cages. Eggs were collected from 200 birds of ISA Brown genotype at 40–42 weeks of age. Half of the birds were housed in enriched cages (750 cm2/hen, 10 hens/cage) and the other half were housed in littered pens (9 hens/m2, 10 hens/pen). Eggs in each housing system were split into three categories varying in shell thickness: the first category (thin shells 0.28–0.30 mm), the second category (medium shells 0.33–0.36 mm) and the third category (thick shells 0.39–0.41 mm). Results indicated that eggshell parameters differ significantly according to eggshell thickness. Significant interaction of shell category and housing system were observed in eggshell strength. As expected, the eggshell strength was increased with eggshells becoming thicker. Moreover, eggs with the thickest shells from enriched cages had significantly stronger shells than those from litter system. Eggshell weight was significantly increased in the thick eggshell category being higher in enriched cages (7.23 g) than in litter system (5.14 g). The Pearson’s correlation coefficients showed a positive correlation between eggshell parameters and eggshell thickness in both housing systems. Moreover, the correlation between eggshell thickness and eggshell strength was higher on litter (0.64,p < 0.001) in comparison with enriched cages (0.48,p < 0.001). Results of the present study indicated that in thin shells, housing system plays an important role in determining the eggshell strength. [ABSTRACT FROM PUBLISHER]

Strategies that would increase eggshell quality could be of considerable value to egg producers. This research demonstrated the effective use of fibroblast growth factor 23 (FGF-23) peptide vaccines to increase eggshell quality of Single Comb White Leghorn laying hens (from 69 to 72 wk of age). Hens, fed a standard diet (containing 900 IU/kg vitamin D3), were intramuscularly injected (and boosted) with either a control vaccine (n = 14 hens) or one of 2 FGF-23 peptide vaccines (peptides NP1, GMNPPPYS; and NP7, YTSTERNSFH; n = 15 hens for each peptide). During peak antibody titer, eggs were collected for shell and internal quality analysis, hens were artificially inseminated, and the hatchability of fertilized eggs was determined. Laying hens vaccinated with either FGF-23 peptide NP1 or NP7 had increased (P < 0.05) plasma phosphate level (mmol/L; NP1 = 1.74, NP7 = 1.76, control = 1.47), egg specific gravity (NP1 = 1.083, NP7 = 1.083, control = 1.079), and eggshell strength (g of force; NP1 = 4002, NP7 = 4157, control = 3102) when compared to control vaccinated hens. FGF-23 peptide NP1 vaccinated hens also had increased eggshell thickness (mm, P < 0.001), shell weight (g, P = 0.032), and shell index (% of whole egg, P = 0.023) when compared to control vaccinated hens. FGF-23 peptide NP7 vaccinated hens tended to have decreased eggshell weight (P = 0.064) when compared to control vaccinated hens. Hatchability of fertilized eggs was not affected in incubations 1 and 3, but tended to be decreased (P = 0.097) by FGF-23 peptide NP1 vaccination in incubation 2. In conclusion, vaccines to FGF-23 peptides increased eggshell quality of laying hens with minimal adverse effects on egg internal quality. The effect of FGF-23 peptide vaccination on hatchability remains to be clarified. [ABSTRACT FROM AUTHOR]

The aim of the study was to assess the condition of eggshells hygienised with an silver stabilized hydrogen peroxide of different concentrations. Eggs were treated with a solution of the preparation and stored for four weeks. In preliminary investigations the elastic deformation of eggshells was measured and analysed in order to determine the influence of a preparation concentrated at 0.01-3% on the eggshell strength. The research proved that a preparation concentrated at 1-3% significantly reduced the eggshell strength. At the next stage of the research, having excluded the high concentrations with a negative effect on eggshell strength, i.e. 1-3%, the experiment was conducted again. It was followed by a microbiological analysis in which the total count of aerobic bacteria, yeasts, moulds ad also bacteria from the Pseudomonas genus and Enterobacteriaceae family were measured. The investigations confirmed that the preparation concentrated at 0.01-0.9% did not have a significant influence on eggshell strength. Hygienisation in solutions concentrated at 0.01-0.9% caused complete inactivation of bacteria of the Enterobacteriaceae family, yeasts and moulds. Immediately after treatment with the preparation concentrated at 0.3% the count of aerobic bacteria and the bacteria of the Pseudomonas genus decreased by 1.9 log CFU/g and 0.7 log CFU/g, respectively. The hygienisation of eggs with the preparation concentrated at 0.9% and storing them for four weeks under controlled conditions reduced the count of aerobic bacteria by 1.9 log and the count of Pseudomonas bacteria by 1.7 log, as compared with the reference sample. [ABSTRACT FROM AUTHOR]

Silkie fowl are very famous in China and Japan, however the egg production rate of the Silkie fowl is very low because of broodiness. Authors have examined the polymorphisms of the 5′-flanking region of the prolactin gene in Taihe Silkie fowl and identified a 24-bp In/Del locus, but no In/In Silkie individuals have been found. In this study, In/In individuals were constructed from an In/Del×In/Del population in order to examine the unique characteristics of Silkies. The relationships between production traits and DNA markers of the three candidate genes were studied. To produce In/In Silkie individuals, male and female individuals with the In/Del locus in the fourth generation of the Silkie fowl selection population were crossed. Genotyping was performed for the prolactin In/Del locus, the DNA marker of neuropeptide Y, and the dopamine D2 receptor. In this study, 27 Del/Del, 39 In/Del, and 21 In/In female individuals and 13 Del/Del, 26 In/Del, and 17 In/In male individuals were found. All In/In individuals had the Silkie fowl characteristics. A significant effect of neuropeptide Y was found on eggshell strength (p

The influence of a developing bird embryo on eggshell thinning is well known, however this phenomenon has been described mainly for poultry, and in wild birds is poorly understood. This study focussed on Capercaillie (Tetrao urogallus), in which the effect of a developing embryo on the change of eggshell thickness has not been described. However, problems relating to a large number of dead embryos and eggs cracking during incubation are observed in captive breeding centres giving us the opportunity to test how the developing embryo affects the eggshell and thereby its properties, including eggshell strength and thickness. In total, 196 unhatched eggs, including 146 infertile and 50 eggs with embryos which died at various stages of development, were analysed in relation to eggshell shape, thickness and strength. Moreover, 102 posthatched eggshells were also examined. Although the strength of eggshell was affected by egg shape and shell thickness, contrary to expectations, the stage of embryonic development had no significant influence on eggshell strength. As has been demonstrated in other species, etching of eggshells by the developing embryo reduces shell thickness in Capercaillie but it has minimal effect on the strength of the eggshell. Egg viability is not compromised during the later stages of development by contact incubation with the female. The eggshell of infertile eggs or eggs containing early-dead embryos were 10% thicker than posthatched eggshells and eggs with late-dead embryos, confirming that eggshell thinning in Capercaillie is typical for precocial species. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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.

An analysis of eggs' quality parameters (egg weight, eggshell strength, eggshell thickness and egg index) was performed in two Lohman Brown flocks of commercial laying hens at advanced age. Two farms equipped with battery cages were the places where the experiment was performed. The first farm (F1) was small, family-owned farm equipped with moderately efficient ventilation, and in the second farm (F2) a highly efficient tunnel ventilation with water pads cooling equipment was installed. Egg weight and eggshell strength were analyzed in the laboratory for testing egg quality, using Egg Multi Tester EMT 5200 and Eggshell Gauge (Robotmation Co. Ltd., Tokyo, Japan), computerized equipment that gives unbiased values, while shell thickness and egg index were measured using a micrometer. No significant differences in the average values of egg size (63.09; 63.33 g), shell thickness (0.38; 0.38 mm) and egg index (75.49; 76.56) were registered between F1 and F2 farms, respectively. Average shell strength values revealed that layers kept on F2 farm produce eggs with stronger eggshell (3,434.16 g/cm²) compared to the farm F1 (3,344.82 g/cm²), mainly due to the fact that the drop of the eggshell quality in the first farm in the hot summer period (July) was drastic (2,914.00 g/cm²). The other explanation of this situation could be the significant drop of egg size in the farm equipped with cooling pads at the beginning of the hot season (May-June) which most probably helps the layers in maintaining their Ca reserves that later help their metabolism maintain its shell-forming capacities. The conclusion is that high summer temperatures influence the eggshell strength resulting in lower strength, but the cooling equipment mitigates this negative effect. [ABSTRACT FROM AUTHOR]

An analysis was performed of eggs' quality parameters in the period of the high-temperature summer (July, August) heat-stress period (egg weight, yolk color, Hough units and eggshell strength) in two flocks of commercial laying hens at advanced age. Each flock consisted of ISA Brown (IB) and DeKalb White (DK) mixed-genetic layers kept in two separate hen-houses equipped with battery cages. The first flock (F1-7334 DK and 8233 IB) was at the 72nd week of age at the start of the monitored period, and the second one (F2-7833 DK and 8815 IB) at the 92nd week of age after being molted at the 70th week of age. In-house environment ventilation as well as hens' feeding (following technical recommendations) were approximately same for both hen-houses throughout the laying cycle. Eggshell quality of 240 egg samples (30 eggs/month/breed F1 or F2) was analyzed in the laboratory for testing egg quality using Eggshell Gauge (Robotmation Co. Ltd., Tokyo, Japan), a computerized equipment that gives unbiased values. Both genotypes yielded high egg production close to the technological level. Molted ISA Brown layers produce eggs that on average have 400 g/cm² stronger shells than the eggs of non-molted layers (mean values of 4,027.63 vs. 3,569.83 g/cm² in July and 3,748.67 vs. 3,334.70 g/cm² in August). Same tendency was registered in DeKalb White layers' flock (mean values of 3,743.83 vs. 3,535.67 g/cm² in July and 3,400.23 vs. 3,104.53 g/cm² in August). The data obtained confirm that heat stress negatively influences shell strength and that molting improves layers' shell strength production capacity and helps mitigation of heat-stress negative effects. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background Economic losses resulting from poor eggshell quality are critical issue for the poultry industry, challenging researchers to find practical solutions to improve the resistance of eggshells to external pressure. Although many studies have proposed non-destructive methods to improve shell strength, relatively few long-term experiments are documented which use non-destructive deformation as a selection criterion. Using REML under a five-trait animal model, this study evaluates a long-term selection experiment for non-destructive deformation that was conducted on two divergent lines of White Leghorns and provides insight into how the selection process affects other traits related to eggshell strength (breaking strength, shell thickness, shell percentage, and shell weight). The evolution of the genetic parameters over the course of the experiment was analyzed also. Results The heritability estimates for non-destructive deformation were 0.388 (±0.032) for the strong line and 0.415 (±0.030) for the weak line. For eggshell breaking strength, heritability values were 0.347 (±0.028) for the strong line and 0.482 (±0.032) for the weak line. Strong genetic correlations were found between non-destructive deformation and eggshell breaking strength (−0.774±0.031 and −0.840±0.022 for the strong and weak lines, respectively). Estimated heritabilities for the other traits varied from 0.448 to 0.591 for the strong line and from 0.493 to 0.672 for the weak line. In addition, these traits showed large negative genetic correlations with non-destructive deformation, from −0.623 to −0.903 for the strong line and from −0.730 to −0.934 for the weak line. Moreover, the regression coefficients associated with the generation means of the breeding values revealed an asymmetric response between the two lines, and further analysis of the evolution of the genetic parameters over the course of the experiment hinted at possible reasons for this asymmetry. Conclusions The large genetic correlation between non-destructive deformation and eggshell breaking strength and the similarity of the heritability estimates for these two traits (medium to moderately high), suggest that non-destructive deformation can be used instead of breaking strength as a means to evaluate eggshell strength. Nevertheless, additional research is necessary to better understand the effect of selection for non-destructive deformation on factors not considered in this study, such as egg production and hatching rate. [ABSTRACT FROM AUTHOR]

The paper deals with the evaluation of the effect of hen breed on the egg response to the nondestructive impact. The eggs of four hen breeds (Leghorn White, Rhode Island Red, Bar Plymouth Rock and Sussex Light) were tested. An experimental system was set up to generate the impact force, measure the response wave signal, and analyse the frequency spectrum in the three direction of loading (sharp end, equator, blunt end). The egg dynamic resonance frequency was obtained through the analysis of the dynamically measured frequency response of an egg excited by light impact of a bar. The results showed that the dominant frequency was significantly affected by the hen bread and not significantly affected by excitation velocity. The dominant frequency enables to estimate the eggshell strength under quasi static compression. [ABSTRACT FROM AUTHOR]

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 mitogen‑activated 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. [ABSTRACT FROM AUTHOR]

Earlier studies on breeding birds indicated no effect of dietary energy-content on feed intake. This observation is contradictory to results for other animals and/or poultry where feed intake decreases with an increase in dietary energy level. Literature revealed that a lack of certain nutrients may cause animals to consume more feed than necessary to satisfy their nutrient requirements for these limiting nutrients. In this study eight diet groups were evaluated. A standard commercial diet plus one of the following supplements: (i) Standard diet without a vitamin and mineral premix pack (control diet), (ii) with a normal premix pack, (iii) with normal vitamin and 2 x trace elements (M x 2), (iv) with normal trace elements and 2 x vitamins, (v) with a normal premix pack and limestone added as calcium source; (vi) with a normal premix pack and monocalcium phosphate added as phosphorus source, (vii) with a normal premix pack and soybean oilcake added as crude protein source, (viii) with a normal premix pack and linseed added as a fatty acid source. Significant differences were recorded in the quantity of feed ingested by birds between the diet with surplus minerals (M x 2) (Group 3) (2.3 ± 0.3 kg/bird/day), the diet with no vitamins and minerals added (Group 1) (2.7 ± 0.3 kg/bird/day) and the diet with added fatty acids in the form of linseed (Group 5) (2.9 ± 0.5 kg/bird/day). This indicates the possibility that ostriches may adjust feed intake to satisfy their mineral requirements. No statistically significant relationship was found between the thickness and strength of the shell. Significant differences in shell strength (mean value of 154.7, 109.9, 140.4, 142.7, 153.0, 143.4, 138.4 and 151.1 N/cm², respectively) were found between all treatments, but no specific pattern could be identified. Results further revealed no effect of dietary treatment on egg production, dead-in-shell eggs (DIS), infertile eggs or chick production. Further experiments that include certain dietary treatments during the five months rest period are currently being done to quantify the effect of the addition of minerals and vitamins during this period on the production of breeding ostriches. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Silkie fowl are very famous in China and Japan, however the egg production rate of the Silkie fowl is very low because of broodiness. Authors have examined the polymorphisms of the 5'-flanking region of the prolactin gene in Taihe Silkie fowl and identified a 24-bp In/Del locus, but no In/In Silkie individuals have been found. In this study, In/In individuals were constructed from an In/DelXIn/Del population in order to examine the unique characteristics of Silkies. The relationships between production traits and DNA markers of the three candidate genes were studied. To produce In/In Silkie individuals, male and female individuals with the In/Del locus in the fourth generation of the Silkie fowl selection population were crossed. Genotyping was performed for the prolactin In/Del locus, the DNA marker of neuropeptide Y, and the dopamine D2 receptor. In this study, 27 Del/Del, 39 In/Del, and 21 In/In female individuals and 13 Del/Del, 26 In/Del, and 17 In/In male individuals were found. All In/In individuals had the Silkie fowl characteristics. A significant effect of neuropeptide Y was found on eggshell strength (p<0.05) in female birds, and a significant effect of prolactin and dopamine D2 receptor gene was found on the body weight at 50 day in male birds (p<0.05). [ABSTRACT FROM AUTHOR]