Oxidative stress is a frequent concern in the breeding of laying hens, and limit the healthy development of poultry. Dexamethasone (DXM) has been demonstrated to induce oxidative stress. Conversely, betaine is an alkaloid with a potent antioxidant activity. The study was designed to investigate the ameliorative effect of betaine on DXM-induced oxidative stress in laying hens. The results revealed that DXM treatment significantly decreased laying rate, shell strength, albumen height, Haugh unit, egg weight, folk weight and albumen weight, alongside increased malondialdehyde (MDA) and decreased total antioxidant capacity (T-AOC) in serum and liver (P < 0.05). In contrast, dietary betaine addition reversed those parameters mentioned above (P < 0.05). Hepatic RNA-seq analysis showed that there existed 110 up- and 88 down-regulated genes in DXM group when compared with the control. Meanwhile there were 117 upregulation and 169 downregulation genes in BT group when compared with DXM group. Besides, we found that dietary betaine addition significantly down-regulated cell adhesion molecules, glycerolipid metabolism and glycolysis gluconeogenesis pathways. In addition, a total of 44 and 94 differential metabolites were identified respectively from Con vs. DXM and DXM vs BT. More importantly, dietary betaine addition significantly increased the levels of pantothenic acid, gamma-Aminobutyric acid, equol and choline, all of which were related to antioxidant and anti-inflammatory properties. Furthermore, gut microbiota analysis indicated that the Chao and Observed_species indexes were remarkably higher in BT group (P<0.05). Heatmap analysis revealed that Subdoligranulum, Prevotella, Blautia, YRC22, Bacteroides, Ruminococcus and Coprococcus were notably restored in BT group (P<0.05). Taken together, our findings collectively illustrate that dietary betaine addition could attenuate DXM-induced oxidative stress, improve egg quality and gut microbes of laying hens.

During storage, irreversible changes occur in eggs, resulting in a decline in their quality, predominantly affecting the albumen. Ovomucoid, a major protein found in egg white, belongs to the Kazal-type serine proteinase inhibitors and serves to protect the embryo from microorganisms. Notably, in chicken eggs, it is a significant allergen. There is a possibility that its polymorphism also influences the quality and stability of table eggs. Hence, this study aimed to evaluate the potential effect of polymorphism in the ovomucoid gene and protein on quality changes during the storage of eggs derived from 2 strains of Japanese quail, encompassing various utility types. Eggs from selected females of laying and meat-type breeds were stored for 14 wk, with egg quality traits assessed 10 times during this duration. DNA was isolated from each female, and sequencing was conducted on all exons of the ovomucoid gene. In total, 5 SNPs were identified in exons and adjacent intronic sequences, with SNP1 (13:12355585), SNP4 (13:12356594), and SNP5 (13:12358538) leading to amino acid substitutions in the ovomucoid protein. Notably, all SNPs except SNP5 were identified in the ovomucoid gene of Japanese quail for the first time. The results demonstrated that in the F33 strain, SNP1, SNP3, and SNP4 exhibited significant associations with egg weight, whereas in the S22 strain, SNP5 significantly affected yolk color and various eggshell quality traits, including eggshell weight, eggshell thickness, and breaking strength, throughout the storage period. Furthermore, a haplotype block containing 2 SNPs (3 and 4) was identified, exhibiting 2 distinct haplotypes that significantly affected egg weight, eggshell weight, and breaking strength at various storage time points during egg quality analyses. These findings provide novel insights into the genetic basis of egg quality during storage and have the potential to be integrated into breeding programs for these strains.

This study aimed to evaluate the effect of different environmental enrichment tools on behavior, welfare, productive performance, and egg quality traits of Naked Neck chickens. A total of 1080 Naked Neck female chickens (30 weeks old) were used in the present study. A completely randomized experimental design, with 3 treatments having 4 replicates of 90 birds each, was applied. Treatments consisted of 3 different range areas A (121.9 m2), B (152.4 m2), and C (190.5 m2). Behavior (walking, feeding/foraging, sitting, aggressiveness wing flapping, perching, dust bathing, and range use), welfare (foot pad dermatitis, lameness, gait score, and feather pecking), productive performance (egg weight, egg production %, egg mass, and feed intake), egg quality traits (morphometry, egg weight, shell, albumen, and yolk characteristics) were evaluated. There was no influence (P > 0.05) of different range area on bird\'s behavior, and egg quality traits except walking and rang usage. The range area C promoted productive performance including egg weight, egg production %, egg mass and feed intake, but it did not influence welfare traits. It might be concluded that Naked Neck chicken when reared in free range with different range enrichments did not reveal any difference regarding behavioral parameters, egg morphometry, and egg quality traits. The range area within minimum length and effectively used environmental enrichments (perching and dust bathing area) should be used for backyard poultry to obtain ideal performance.

Indigenous animal genetic resources should be preserved because of their well adaptation to the environment, their tolerance to low food availability and their sociocultural importance. The characterization of the quality of the products generated by heritage breeds may bring more arguments to encourage the raising of these animals. This study aimed at evaluating the egg performance and quality of Spanish indigenous Black Castellana (BC) breed as compared with a selected strain (Lohmann LSL-Classic). Four groups of 30 hens were arranged: 1) Lohmann hens fed a control diet; 2) BC hens fed the control diet; 3) Lohmann hens fed a diet including linseed at 70 g/kg (omega-3 diet); 4) BC hens fed the omega-3 diet. Egg production was higher by 12.3% for Lohmann hens but, since BC eggs were heavier by 15.4%, no effect of genetics was found on daily egg mass. Feed intake was higher by 5.0% for BC hens. Nonetheless, no difference was detected for feed conversion ratio. Eggshell was thicker by 6.78% in Lohmann eggs. Haugh units did not differ among freshly laid and stored eggs in Lohmann hens, whereas Haugh units decreased in stored BC eggs (80.5 vs. 76.7 vs. 72.3 at 0, 14, and 30 d of storage). Yolks of BC eggs contained less fat (57.5 vs. 60.8% DM), more protein (32.8 vs. 31.9% DM) and more cholecalciferol (1.25 vs. 1.22 μg/g DM), and showed lower proportion of saturated fatty acids (29.0 vs. 37.0%) and higher proportions of monounsaturated (45.7 vs. 39.6%) and polyunsaturated (25.2 vs. 23.4%) fatty acids. Feeding the omega-3 diet reduced the yolk proportions of saturated (32.5 vs. 33.5%) and monounsaturated (42.0 vs. 43.3%) fatty acids and increased those of polyunsaturated (25.4 vs. 23.2%) and ω-3 (7.05 vs. 2.42%) fatty acids. No effect due to genetics or diet was found on yolk color score or on yolk content in cholesterol, cobalamin, retinol and γ-tocopherol. This study represents the first exhaustive characterization of eggs from Spanish indigenous Black Castellana breed.

Micelle silymarin (MS) is recognized for its diverse range of beneficial properties, which encompass anti-inflammatory, antioxidant, hepatoprotective, and antidiabetic effects. The main objective of this study was to examine the effects of micelle silymarin on the performance, egg quality, blood profile, and absorption rate of silymarin in laying hens. In experiment 1: 288 Hy-Line brown laying hens, 28 wk old, were utilized for this experiment. The hens were randomly allocated into 3 dietary treatment groups, with each group comprising eight replicates of 12 hens, each housed in individual pens with access to feed and water. Over a 12-wk feeding trial, the hens were provided with a basal diet supplemented with different levels of MS: 0, 0.03, and 0.06%. In experiment 2: For this experiment, 192 Hy-Line Brown laying hens were divided into 2 dietary treatment groups, with each group comprising eight replications of 12 hens. The dietary treatments were: TRT1, basal diet + powder silymarin 4%; TRT2, basal diet + MS 4%. From the first experiment, the findings revealed that incorporating micelle silymarin (MS) into the hens\' diet significantly increased egg weight at wk 6 (P < 0.05). Similarly, at wk 12 and throughout the entire experiment, significant effects were observed on downgraded egg count, egg production, egg weight, and feed conversion ratio (FCR) (P < 0.05). Moreover, Haugh Units (HU) and albumen height showed a linear improvement (P < 0.05) at wk 4 with MS supplementation. Furthermore, there was a linear increase in egg yolk color, albumen height, and eggshell thickness at wk 8 with MS supplementation (P < 0.05). Furthermore, a layers-fed diet supplemented with MS showed a linear increase (P < 0.05) in HU, egg weight, yolk color, albumen height, eggshell strength, and eggshell thickness in wk 12. Regarding blood profile parameters, the study revealed linear reductions for aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) (P < 0.05), whereas there was a tendency for albumin, triglyceride, and cholesterol (P < 0.10). In the second experiment, it was observed that the blood absorption rate of silymarin was higher in TRT2 compared to TRT1 at 2- and 4-h intervals following administration. In summary, increasing MS supplementation in the diet of laying hens enhanced egg production, egg quality, and blood profile. Additionally, silymarin absorption was higher in its micelle form than in its powder form.

Genistein (GEN) and Glycitein (GLY), are types of isoflavone extracted mainly from soy plants, although GEN is associated with stronger antioxidant and growth-promoting effects. The impact of dietary GEN and GLY on reproductive performance, egg quality, and bone quality were investigated in the study. Additionally, to explore the underlying mechanism of action, the serum hormone levels and reproductive-related genes were investigated. A total of 378 Hy-Line Brown laying hens (120 days old) were randomly allocated to 3 dietary groups (Control), (GLY, and GEN at 50 mg/kg respectively) for a period of 8 wk. Each treatment has 126 birds (7 replicates of 18 birds each). Results were analyzed in 2 phases: wk 1 to 4, and 5 to 8 of feeding trial. The results indicated that supplemental GEN significantly increased egg number, hen-day production (HDP), and egg mass during wk 1 to 4, whereas, both glycitein and genistein increased egg number, egg weight, egg mass, HDP and improved feed-egg-ratio during wk 5 to 8. Egg quality analysis revealed significant improvements in eggshell quality; gloss, thickness, strength, and albumen quality indices (albumen height, Haugh unit, thick albumen fraction) due to dietary treatments. Also, the tibia strength, Ca content in the tibia ash and bone mineral content, were significantly increased by the dietary treatments. Significant increases in the serum levels of E2, LH, FSH, T3, T4, and GH, and the activity of antioxidant enzymes; SOD, CAT, GSH while reducing the level of MDA, was notable with the treatments. Additionally, reproductive-related genes: ESR1, FSHR, PRLR, GNRH1 were significantly upregulated by the supplementation of GEN and GLY. The efficacy of GEN in relation to the evaluated parameters was superior to that of GLY. Conclusively, we speculate that the improvement on laying performance, egg quality and tibia quality may be related to promoting effect of isoflavones on calcium metabolism, antioxidant function, reproductive hormones and related genes. Therefore, supplemental GEN at a dosage level of 50 mg/kg, can be used to promote laying performance, sustain egg production and maintain the physiological function of young laying hens.

Yeast culture (YC) plays a significant role in enhancing the performance and health of poultry breeding. This study investigated the impact of different YC supplementation concentrations (basal diet with 1.0 g/kg and 2.0 g/kg of YC, YC1.0, and YC2.0) on egg production performance, egg quality, antioxidant properties, intestinal mucosal structure, and intestinal flora of laying hens. Both YC1.0 and YC2.0 groups significantly enhanced the egg protein height, Haugh unit, and crude protein content of egg yolks compared to the control group (p < 0.05). The supplementation with YC2.0 notably increased the egg production rate, reduced feed-to-egg ratio, and decreased the broken egg rate compared to the control group (p < 0.05). Additionally, YC supplementation enhanced serum total antioxidant capacity (T-AOC) and glutathione peroxidase (GSH-PX) activity while reducing malondialdehyde (MDA) content (p < 0.05). Moreover, YC supplementation promoted duodenal villus height and villus ratio in the duodenum and jejunum (p < 0.05). Analysis of cecal microorganisms indicated a decrease in Simpson and Shannon indices with YC supplementation (p < 0.05). YC1.0 reduced the abundance of Proteobacteria, while YC2.0 increased the abundance of Bacteroidales (p < 0.05). Overall, supplementation with YC improved egg production, quality, antioxidant capacity, intestinal morphology, and cecal microbial composition in laying hens, with significant benefits observed at the 2.0 g/kg supplementation level.

Supply problems and rising soybean meal prices have an impact on increasing feed costs. Hemp seed meal (HSM) with high protein content has the potential to be used as an alternative to soybean meal. This study evaluated the impact of dietary HSM of Narlı Sarayı variety as a substitute for soybean meal on productive performances, egg quality and yolk fatty acid composition. A total of 120 Lohmann Brown laying hens aged 50 weeks were allocated into 4 groups and 10 repetitions. Birds received treatment without HSM (control group), or soybean meal substituted with 4%, 8% and 12% HSM. Dietary 4% significantly increased (p < 0.05) egg production and decreased FCR compared with 8% and 12% HSM group but did not differ from the control group in an overall period of 6 weeks. The inclusion of the 12% HSM group significantly decreased (p < 0.05) egg production. Meanwhile, there was no influence of hemp seed meal (p > 0.05) on feed intake, egg weight, body weight change, egg shape index, albumen index, albumen weight, Haugh unit, yolk weight, yolk index and eggshell thickness. Dietary 8% and 12% HSM significantly increased (p < 0.05) eggshell weight and yolk colour compared with control and 4% HSM groups. There was a significant increase (p < 0.05) in omega-3 fatty acid concentration and a decrease in yolk omega-6 to omega-3 fatty acids ratio with an increase in dietary HSM. It was concluded that dietary up to 12% HSM of the Narlı Sarayı variety decreased egg production and increased FCR. Increasing dietary levels of HSM increased eggshell weight, yolk colour and omega-3 fatty acids content and decreased the omega-6 to omega-3 fatty acids ratio.

This study investigated the effects of dietary chlorogenic acid (CGA) on the productive and reproductive performance, egg quality, antioxidant function, and intestinal microenvironment of laying hens. Thus, 162 healthy Hy-Line Brown breeding hens (63 weeks old) were randomly allocated to 3 groups, each receiving a basal diet plus supplementation: 0, 250, and 500 mg/kg CGA, respectively. Per the in vitro test, CGA had obvious inhibitory effects on Salmonella enteritis and avian pathogenic Escherichia coli and strong free radical scavenging ability. Per the breeder laying hen experiment, the CGA diets had no significant influence on egg production or reproductive performance (P < 0.05). Nevertheless, compared with the control diet, 250 mg/kg CGA significantly increased eggshell thickness, egg weight, yolk color, and Haugh unit (P < 0.05). Compared with the control diet and 500 mg/kg CGA, 250 mg/kg CGA significantly (P < 0.05) elevated antioxidant capacity by reducing serum malondialdehyde content, upregulating heme oxygenase-1, and downregulating heat shock proteins mRNA levels in the ileum. Compared with the control diet and 500 mg/kg CGA, 250 mg/kg CGA (P < 0.05) enhanced intestinal barrier function, shown by the upregulation of ileal Occludin and Mucin-2 mRNA levels; furthermore, 250 mg/kg CGA (P < 0.05) increased anti-apoptotic capacity by increasing B-cell leukemia/lymphoma 2 gene expression and downregulated Bcl2 Associated X mRNA levels in the liver and ileum of late breeder laying hens (P < 0.05). Lastly, 250 mg/kg CGA (P < 0.05) increased cecal g_CHKCI001 and short-chain fatty acid-producing bacteria g_Prevotellaceae UCG-001, positively related to gut health, and in the cecum, 500 mg/kg CGA significantly (P < 0.05) increased g_Shuttleworthia abundance, negatively related to gut health. Our findings suggest that dietary inclusion of 250 mg/kg CGA promotes egg quality, intestinal microbial composition, gut barrier integrity, and the antioxidant capacity of aged breeder laying hens.

Dietary calcium supply is essential for bone development and egg production in laying hens. This study investigated the effects of low dietary calcium and lipopolysaccharide (LPS) induced immune challenge in aged laying hens. A total of thirty-two Hy-Line Brown laying hens at 80 weeks old with an average laying rate of 62% were randomly divided into two groups and fed a normal calcium diet (3.57% Ca, NCA) or low calcium diet (2.08% Ca, LCA). At 88 weeks, the experiment was designed using a 2 × 2 factorial arrangement, and hens were intraperitoneally injected with saline (SAL) or LPS (0.5 mg/kg, 0.5 mg/kg, or 1.5 mg/kg body weight) once every 48 h intervals over 5 days. Production performance, egg quality, and bone physiology were evaluated. Results showed that LPS challenge decreased the hen-day egg production, egg mass, and eggshell traits (p < 0.05), but increased (p < 0.05) the calcium content of the tibia compared to SAL-injected hens. LCA diet decreased (p < 0.05) the hen-day egg production, and eggshell traits such as weight, percentage, strength, and thickness compared to the NCA diet. LCA diet increased the serum alkaline phosphatase (ALP) activity (p < 0.01) and tibial expression of ALP (p < 0.05) compared to NCA diet. LPS injection suppressed both the serum ALP activity (p < 0.05) and tibial expression of ALP (p < 0.001) compared to SAL injection. Furthermore, LPS injection increased (p < 0.05) the expression of both pro and anti-inflammatory cytokines in the spleen and tibia. The expression of cathepsin K ( Cts K ) and matrix metalloproteinase 9 ( MMP-9 ) were downregulated by LPS injection (p < 0.001). Broken and shell-less egg production and calcium content of eggshell, as well as tibial mRNA expression of osteocalcin ( Ocn ), tumor necrosis factor-alpha ( TNF-α ) and tartrate-resistant acid phosphatase ( TRAP ) were affected by the interaction (p < 0.05) of diet and injection. Therefore, this study demonstrated that to certain extents, low dietary calcium and LPS challenge dysregulated bone homeostasis and metabolism, with detrimental effects on the performance and eggshell quality of aged laying hens.