Pituitary transcriptome profile from laying period to incubation period of Changshun green-shell laying hens.

BACKGROUND: Incubation behaviour, an instinct for natural breeding in poultry, is strictly controlled by the central nervous system and multiple neuroendocrine hormones and neurotransmitters, and is closely associated with the cessation of egg laying. Therefore, it is essential for the commercial poultry industry to clarify the molecular regulation mechanism of incubation behaviour. Here, we used high-throughput sequencing technology to examine the pituitary transcriptome of Changshun green-shell laying hen, a local breed from Guizhou province, China, with strong broodiness, in two reproductive stages, including egg-laying phase (LP) and incubation phase (BP). We also analyze the differences in gene expression during the transition from egg-laying to incubation, and identify critical pathways and candidate genes involved in controlling the incubation behaviour in the pituitary. RESULTS: In this study, we demonstrated that a total of 2089 differently expressed genes (DEGs) were identified in the pituitary, including 842 up-regulated and 1247 down-regulated genes. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that steroid biosynthesis pathway and neuroactive ligand-receptor interaction were significantly enriched based on DEGs commonly identified in pituitary. Further analysis revealed that SRC, ITGB4, ITGB3, PIK3R3 and DRD2 may play crucial roles in the regulation of incubation behaviour. CONCLUSIONS: We identified 2089 DEGs and the key signaling pathways which may be closely correlated with incubation in Changshun green-shell laying hens, and clarified the molecular regulation mechanism of incubation behaviour. Our results indicate the complexity and variety of differences in reproductive behaviour of different chicken breeds.

Differential analysis of ovarian tissue between high and low-yielded laying hens in the late laying stage and the effect of LECT2 gene on follicular granulosa cells proliferation.

The ovaries of high-yield laying hens exhibited signs of aging beyond 400 days of age, subsequently resulting in a decline in both egg production and egg quality. Oxidative stress, characterized by an increase in the production of reactive oxygen species (ROS), stands as one of the principal processes contributing to ovarian aging. Elevated ROS levels are implicated in the induction of apoptosis in granulosa cells (GCs), provoking mitochondrial impairment, and diminishing the capacity of the antioxidant defense system. This investigation stratified laying hens into two distinct groups, predicated upon their egg production levels: high-yield hens (HH) and low-yield hens (LL). The study focused on evaluating oxidative stress markers and identifying differentially expressed genes between these two groups. The findings revealed that the LL group exhibited follicular atresia, mitochondrial disruptions, and apoptotic occurrences in ovarian GCs. Notably, ROS levels, Malondialdehyde (MDA) concentrations, and 8-hydroxy-2'-deoxyguanosine (8-OHdG) concentrations in ovarian tissue and follicular GCs were substantially higher in the HH group. Furthermore, the RNA-sequencing results unveiled differential expression of the LECT2 gene between the HH and LL groups. Consequently, an overexpression vector for the LECT2 gene was successfully constructed and introduced into GCs. The quantitative polymerase chain reaction (QPCR) analysis exhibited significant downregulation (p < 0.01) of key apoptotic genes such as Caspase-3 and C-myc and significant upregulation (p < 0.01) of BCL2 following the overexpression of the LECT2 gene in GCs. In conclusion, oxidative stress emerges as a pivotal factor influencing the laying traits of both high and low-yield laying hens. The accumulation of reactive oxygen species (ROS) within the ovaries precipitates apoptosis in GCs, subsequently leading to follicular atresia and a reduction in egg production. Furthermore, we employed RNA sequencing technology to examine the ovarian matrix tissue in high and low laying hens during the late phase of egg laying. Our analysis revealed a substantial upregulation of the LECT2 gene in the ovarian matrix tissue of high laying hens. This observation implies that the LECT2 gene exerts a pivotal influence on driving the proliferation and differentiation of follicular GCs, thereby exerting a crucial regulatory role in follicular development.

Age of challenge is important in Salmonella Enteritidis studies in pullets and hens: a systematic review.

RESEARCH HIGHLIGHTS: Salmonella challenge chicken models do not always achieve high colonization levels in controls.The age of hen is important in achieving good caecal colonization.Challenge around sexual maturity provides the best control colonization outcome.A challenge dose rate of 105 CFU/ bird is adequate in birds under 30 weeks of age.

Interference between Escherichia coli genotypes from the E. coli peritonitis syndrome given simultaneously to productive SPF White Leghorn hens by intratracheal inoculation.

The purpose of the present study was to examine if potentiation of mortality occurred after simultaneous administration of several Escherichia coli genotypes, each capable of inducing the E. coli peritonitis syndrome, in comparison with single genotype application. Five groups of productive specified pathogen free White Leghorn hens were housed in isolators. Groups 1-4 consisted of 32 hens each, group 5 of 10 hens. At 32 weeks of age all groups were inoculated intratracheally. Groups 1 and 2 were inoculated with a mix of four E. coli genotypes and groups 3 and 4 with a mix of four other genotypes. Groups 1 and 3 were given 1 median lethal dose (LD50) of each genotype per hen and groups 2 and 4 had a dose of 0.1 LD50 per genotype per hen; group 5 was mock inoculated. The experiment ended one week after inoculations. In Group 5, no mortality occurred and gross lesions were absent at post-mortem examination. Mortality in groups 1 and 3 was 84% and 81%, respectively; in groups 2 and 4 59% and 66%, respectively. Although mortality in groups 1 and 3 exceeded the expected 50%, this could not be due to potentiation as cluster analysis of reisolates showed that in individual hens only one genotype was found, indicating interference between E. coli genotypes. In groups all four or only two genotypes were recovered, showing that not all genotypes will induce colibacillosis in all experimental groups. Therefore, broad protection can be best assessed by challenging with various single genotypes.RESEARCH HIGHLIGHTS All four or only two E. coli genotypes were found in groups of hens given mixes of four genotypes.In contrast, only one genotype was found in individual hens.E. coli genotypes interfere with each other in hens after given as a mix.Interference is likely based on a random process.Broad protection can best be assessed by challenging with single genotypes.

Orychophragmus violaceus and/or chicory forage affects performance, egg quality, sensory evaluation and antioxidative properties in native laying hens.

Orychophragmus violaceus (OV) and chicory (Cichorium intybus L., CC) can be used as fresh or dry forage for animals. To determine whether OV and/or CC have beneficial effects on performance and egg quality, a total of 1212 28-wk-old Beijing You Chicken (BYC) laying hens with similar performance were randomly allocated to 4 groups with 3 replicate pens per group, and 101 birds per pen. The birds were fed a basal diet (control), the basal diet + OV (3.507 kg/d/pen), the basal diet + CC (2.525 kg/d/pen), and the basal diet + OV + CC (OVC, 1.7535 kg/d/pen OV + 1.2625 kg/d/pen CC) for 3 wks after one wk of adaptation. The results showed that egg-laying rate was not affected by OV, CC and OVC (p > 0.05), but weekly average egg mass was significantly increased by OV and CC (p < 0.05). The feed egg ratio in the CC group (2.82) was significantly lower than that in the other three groups (p < 0.05). The eggshell thickness (EST), albumen height (AH) and Haugh unit (HU) were decreased by OV and CC (p < 0.05); while yolk color (YC) was increased in the CC and OVC groups (p < 0.05). Egg grade was decreased by OV (p < 0.05). Sensory evaluation showed that there was a trend for increased YC in OV, CC and OVC (p = 0.089). Serum total protein was significantly lower in OV group than those in the control and CC group (p < 0.05); serum albumin content was significantly decreased in OV, CC and OVC groups (p = 0.006). Serum glutathione peroxidase activity in CC and OVC groups was significantly higher than that in the control group (p < 0.05). In conclusion, the present study suggests that CC had a better effect on the performance of the native laying hens than OV. The OV and CC affected egg quality, while YC was increased in CC and OVC groups. The OVC improved YC and serum antioxidative properties of native laying hens without affecting the performance.

Effects of selenium-enriched yeast dietary supplementation on egg quality, gut morphology and caecal microflora of laying hens.

Selenium (Se) is an essential micronutrient for humans and animals and is a powerful antioxidant that can promote reproductive and immune functions. The purpose of this study was to evaluate the effects of supplemental dietary selenium-enriched yeast (SeY) on egg quality, gut morphology and microflora in laying hens. In total, 100 HY-Line Brown laying hens (45-week old) were randomly allocated to two groups with 10 replicates and fed either a basal diet (without Se supplementation) or a basal diet containing 0.2 mg/kg Se in the form of SeY for 8 weeks. The Se supplementation did not have a significant effect on egg quality and intestinal morphology of laying hens. Based on the 16S rRNA sequencing, SeY dietary supplementation effectively modulated the cecal microbiota structure. An alpha diversity analysis demonstrated that birds fed 100 mg/kg SeY had a higher cecal bacterial diversity. SeY dietary addition elevated Erysipelotrichia (class), Lachnospiraceae (family), Erysipelotrichaceae (family) and Ruminococcus_torques_group (genus; p < .05). Analysis of microbial community-level phenotypes revealed that SeY supplementation decreased the microorganism abundance of facultatively anaerobic and potentially pathogenic phenotypes. Overall, SeY supplementation cannot significantly improve intestinal morphology; however, it modulated the composition of cecal microbiota toward a healthier gut.

Synergistic cooperation between the ß-catenin and SF1 regulates progesterone synthesis in laying hen ovarian granulosa cells.

The development of ovarian follicles in poultry is a key factor affecting the performance of egg production. Ovarian follicle development is regulated via the Wnt/ß-catenin signaling pathway, and ß-catenin, encoded by CTNNB1, is a core component of this pathway. In this study, using ovary GCs from laying hens, we investigated the regulatory role of CTNNB1 in steroid synthesis. We found that CTNNB1 significantly regulates the expression of StAR and CYP11A1 (key genes related to progesterone synthesis) and the secretion of progesterone (P4). Furthermore, simultaneous overexpression of CTNNB1 and SF1 resulted in significantly higher levels of CYP11A1 and secretion of P4 than in cells overexpressing CTNNB1 or SF1 alone. We also found that in GCs overexpressing SF1, levels of CYP11A1 and secreted P4 were significantly greater than in controls. Silencing of CYP11A1 resulted in the inhibition of P4 secretion while overexpression of SF1 in CYP11A1-silenced cells restored P4 secretion to normal levels. Together, these results indicate that synergistic cooperation between the ß-catenin and SF1 regulates progesterone synthesis in laying hen ovarian hierarchical granulosa cells to promote CYP11A1 expression.

Chronic dietary deoxynivalenol exposure interferes the intestinal microbial community structure and antibiotic resistome in laying hens.

Antibiotic resistance genes (ARGs) are critical emerging pollutants that have attracted considerable attention. Deoxynivalenol (DON) is one of the most prevalent mycotoxins in cereal crops worldwide, arising severe health hazards to both humans and animals. Even if numerous researches argue in favor of a notorious influence of DON on the gut, the effects of dietary DON exposure on the ARG profile in poultry intestine remain obscure. In this study, two separate feeding experiments using Jing Tint 6 laying hens exposed to 4.5 or 9.0 mg/kg DON were performed to explore the impact of dietary DON exposure on the microbial community structure and the profiles of ARGs in the intestine via 16S rDNA sequencing and metagenomics sequencing, respectively. In addition, growth performance and intestinal barrier function were also determined to assess the feasibility of using DON-contaminated feedstuffs inappropriate for pigs' consumption in laying hens. Chronic ingestion of DON at 9.0 mg/kg did not alter zootechnical parameters. However, histomorphological impairments were observed in liver and jejunum. Additionally, metagenomic sequencing revealed that dietary DON exposure at 9.0 mg/kg level dramatically changed the gut microbial structure and shifted the ARG profile. The abundance of tetracycline ARG subtype in the layer cecum was decreased, whereas the abundance of vancomycin ARG subtype was increased upon DON exposure. Co-occurrence network analysis identified that Prevotella was the major ARG host in the intestine of laying hens. In summary, our findings demonstrated that DON-contaminated feedstuffs inappropriate for pigs' consumption should be prudently used in hen production, and shed new light on the interactions between mycotoxins and ARGs in the poultry intestine.

MicroRNA-129-1-3p protects chicken granulosa cells from cadmium-induced apoptosis by down-regulating the MCU-mediated Ca2+ signaling pathway.

Cadmium (Cd) is known as a female reproductive toxicant. Our previous study has shown that Cd can influence the proliferation and cell cycle of granulosa cells and induce apoptosis. MicroRNAs (miRNAs) play an important role in the regulation of Cd-induced granulosa cell damage in chickens. However, the mechanism remains unclear. In this study, we investigated the mechanisms by which microRNA-129-1-3p (miR-129-1-3p) regulates Cd-induced cytotoxicity in chicken granulosa cells. As anticipated, exposure to Cd resulted in the induction of oxidative stress in granulosa cells, accompanied by the downregulation of antioxidant molecules and/or enzymes of Nrf2, Mn-SOD, Cu-Zn SOD and CAT, and the upregulation of Keap1, GST, GSH-Px, GCLM, MDA, hydrogen peroxide and mitochondrial reactive oxygen species (mtROS). Further studies found that Cd exposure causes mitochondrial calcium ions (Ca2+) overload, provoking mitochondrial damage and apoptosis by upregulating IP3R, GRP75, VDAC1, MCU, CALM1, MFF, caspase 3, and caspase 9 gene and/or protein expressions and mitochondrial Ca2+ levels, while downregulating NCX1, NCLX and MFN2 gene and/or protein expressions and mitochondrial membrane potential (MMP). The Ca2+ chelator BAPTA-AM or the MCU inhibitor MCU-i4 significantly rescued Cd-induced mitochondrial dysfunction, thereby attenuating apoptosis. Additionally, a luciferase reported assay and western blot analysis confirmed that miR-129-1-3p directly target MCU. MiR-129-1-3p overexpression almost completely inhibited protein expression of MCU, increased the gene and protein expressions of NCLX and MFN2 downregulated by Cd, and attenuated mitochondrial Ca2+ overload, MMP depression and mitochondria damage induced by Cd. Moreover, the overexpression of miR-129-1-3p led to a reduction in mtROS and cell apoptosis levels, and a suppression of the gene and protein expressions of caspase 3 and caspase 9. As above, these results provided the evidence that IP3R-MCU signaling pathway activated by Cd plays a significant role in inducing mitochondrial Ca2+ overload, mitochondrial damage, and apoptosis. MiR-129-1-3p exerts a protective effect against Cd-induced granulosa cell apoptosis through the direct inhibition of MCU expression in the ovary of laying hens.

Deoxynivalenol and T-2 toxin cause liver damage and egg quality degradation through endoplasmic reticulum stress in summer laying hens.

The present study aimed to find whether low doses of mixed mycotoxins would affect egg quality in laying hens, and to explore the oxidative stress induced liver damage through endoplasmic reticulum during summer stress. A total of 96 Jinghong laying hens, 36 wks of age, were divided into four treatments, with eight repetitions per treatment and three hens per repetition. All the hens were raised in summer (average temperature: 31.3 ± 0.5℃; average humidity: 85.5 ± 0.2%) for 28d. One treatment was fed a basal diet as control (CON), and the other three treatments were fed the same diets containing 3.0 mg/kg deoxynivalenol (DON), 0.5 mg/kg T-2 toxin (T-2), and 1.5 mg/kg DON + 0.25 mg/kg T-2 toxin (Mix). Albumen height and Haugh unit were decreased (P < 0.05) in the Mix group on day 14 and 28. The activity of total antioxidant capacity, glutathione peroxidase, catalase, and superoxide dismutase were decreased (P < 0.05) in the DON, T-2, and Mix groups. The alkaline phosphatase level in DON, T-2, and Mix groups was significantly increased (P < 0.05). The level of interleukin-1ß, interferon-γ, and tumor necrosis factor-α in the Mix group were higher (P < 0.05) than CON, DON, and T-2 groups. Mix group upregulated the mRNA expressions of protein kinase RNA-like ER kinase, activating transcription factor4, IL-1ß, nuclear factor-κ-gene binding, and nuclear respiratory factor 2 in the liver (P < 0.05). The results showed that low doses of DON and T-2 toxin could cause oxidative stress in the liver, but DON and T-2 toxin have a cumulative effect on virulence, which can reduce egg quality and cause endoplasmic reticulum stress in the liver.

CircEML1 facilitates the steroid synthesis in follicular granulosa cells of chicken through sponging gga-miR-449a to release IGF2BP3 expression.

Non-coding RNAs (ncRNAs) induced competing endogenous RNAs (ceRNA) play crucial roles in various biological process by regulating target gene expression. However, the studies of ceRNA networks in the regulation of ovarian ovulation processing of chicken remains deficient compared to that in mammals. Our present study revealed that circEML1 was differential expressed in hen's ovarian tissues at different ages (15 W/20 W/30 W/68 W) and identified as a loop structure from EML1 pre-mRNA, which promoted the expressions of CYP19A1/StAR and E2/P4 secretion in follicular granulosa cells (GCs). Furthermore, circEML1 could serve as a sponge of gga-miR-449a and also found that IGF2BP3 was targeted by gga-miR-449a to co-participate in the steroidogenesis, which possibly act the regulatory role via mTOR/p38MAPK pathways. Meanwhile, in the rescue experiment, gga-miR-449a could reverse the promoting role of circEML1 to IGF2BP3 and steroidogenesis. Eventually, this study suggested that circEML1/gga-miR-449a/IGF2BP3 axis exerted an important role in the steroidogenesis in GCs of chicken.

Effect of Curcumin on Hepatic mRNA and lncRNA Co-Expression in Heat-Stressed Laying Hens.

Heat stress is an important factor affecting poultry production; birds have a range of inflammatory reactions under high-temperature environments. Curcumin has anti-inflammatory and antioxidant effects. The purpose of this experiment was to investigate the effect of dietary curcumin supplementation on the liver transcriptome of laying hens under heat stress conditions. In the animal experiment, a total of 240 Hy-Line brown hens aged 280 days were divided randomly into four different experimental diets with four replicates, and each replicate consisted of 15 hens during a 42-D experiment. The ambient temperature was adjusted to 34 ± 2 °C for 8 h per day, transiting to a range of 22 °C to 28 °C for the remaining 16 h. In the previous study of our lab, it was found that supplemental 150 mg/kg curcumin can improve production performance, antioxidant enzyme activity, and immune function in laying hens under heat stress. To further investigate the regulatory mechanism of curcumin on heat stress-related genes, in total, six samples of three liver tissues from each of 0 mg/kg and 150 mg/kg curcumin test groups were collected for RNA-seq analysis. In the transcriptome analysis, we reported for the first time that the genes related to heat stress of mRNA, such as HSPA8, HSPH1, HSPA2, and DNAJA4, were co-expressed with lncRNA such as XLOC010450, XLOC037987, XLOC053511, XLOC061207, and XLOC100318, and all of these genes are shown to be down-regulated. These findings provide a scientific basis for the possible benefits of dietary curcumin addition in heat-stressed laying hens.

Effects of dietary supplement of ε-polylysine hydrochloride on laying performance, egg quality, serum parameters, organ index, intestinal morphology, gut microbiota and volatile fatty acids in laying hens.

BACKGROUND: ε-polylysine hydrochloride (ε-PLH) is a naturally occurring antimicrobial peptide extensively utilized in the food and medical industries. However, its impact on animal husbandry remains to be further explored. Therefore, the present study aimed to determine the effect of ε-PLH on laying hens' health and laying performance. RESULTS: Dietary supplementation with ε-PLH to the diet significantly increased average egg weight during weeks 1-8. Meanwhile, compared with the control group, supplementation with ε-PLH decreased the feed egg ratio during weeks 9-12 and egg breakage rate during weeks 9-16 ，whereas it increased eggshell strength during weeks 1-4 and 13-16 . The ε-PLH 0.05% group increased yolk percentage during weeks 5-8 and yolk color during weeks 1-4 . Furthermore, ε-PLH supplementation significantly increased the concentrations of total protein, albumin, globulin and reproductive hormones estradiol, as well as decreased interleukin-1 beta and malondialdehyde in the serum. Compared with the control group, supplementation with 0.05% ε-PLH significantly increased the relative abundance of Cyanobacteria and Gastranaerophilales and decreased the abundance of Desulfovibrio and Streptococcus in the cecum microbiota. In addition, ε-PLH 0.1% supplementation also increased acetic acid content in the cecum. CONCLUSION: Dietary supplementation with ε-PLH has a positive impact on both productive performance and egg quality in laying hens. Furthermore, ε-PLH can also relieve inflammation by promoting the immunity and reducing oxidative damage during egg production. ε-PLH has been shown to improve intestinal morphology, gut microbial diversity and intestinal health. © 2023 Society of Chemical Industry.

Effects of different housing systems on the oxidative defence system, heterophil functions, cellular immune response and cytokines in laying hens.

1. This study investigated the effects of different housing systems on oxidative defence mechanisms, heterophil functions, cellular immune response and cytokine production in laying hens. One hundred and twenty laying hens were allocated into one of four groups: conventional cages, furnished cages, deep litter, and free range.2. Housing system did not affect malondialdehyde concentrations and enzymatic antioxidant status. Ascorbic acid values were higher in deep-litter hens than in those in conventional cages and free range.3. Phagocytic and chemotactic activities tended to rise in the deep-litter system, and oxidative burst was higher than in furnished cages. Cytotoxic T cells were decreased in furnished cages, both cytotoxic and helper T cells decreased in deep litter compared to free range.4. The IL-2 and IL-13 expression was higher in deep litter than in conventional cages, and IL-6 expression was higher in furnished cages than in free range.5. Housing system had no significant effects on the oxidative defence system; however, they affected heterophil functions, cellular defence mechanisms and cytokine production. The results suggested that breeders need to consider the housing system's potential effects on immune defence responses while applying a breeding strategy appropriate for animal welfare and consumer demand.

The impact of dietary oregano essential oil supplementation on fatty acid composition and lipid stability in eggs stored at room temperature.

*1. In many countries, eggs are not refrigerated and must be stored at room temperature. The objective of this study was to explore the effects of dietary oregano oil (275 mg/kg; ORE) versus an unsupplemented control diet (CON) on laying hens on the shelf life and fatty acid profile of eggs.2. Treatments were randomly distributed into 10 pens containing 27 birds each. A total of 200 eggs were collected from both groups on the same day and were stored for either 0, 10, 21 and 35 d. At each storage time, egg yolks were analysed for fatty acid profile and lipid peroxidation.3. The main indicator of lipid peroxidation, malondialdehyde (MDA), was significantly lower in ORE eggs compared to CON eggs (p = 0.001). Storage time had a significant impact on MDA concentrations (p = 0.023), with the highest found after 35 d. Significant differences were found for individual fatty acids, saturated (SFA), monounsaturated (MUFA) and polyunsaturated fatty acids (PUFA). Palmitic acid, stearic acid, oleic acid, linoleic acid and arachidonic acid were significantly lower in ORE eggs compared to CON eggs (p < 0.05). Palmitoleic acid (p = 0.002), linolenic acid (p = 0.001) and docosahexaenoic acid (DHA, p = 0.001) were significantly higher in ORE eggs.4. Storage only affected oleic, linolenic, linoleic, arachidonic and docosahexaenoic acids (p < 0.05). Total SFA, MUFA, n-6 and ratio of n-3 to n-6 (n-3:n-6) PUFA were significantly higher in CON eggs (p < 0.05). The ratio of SFA to PUFA (SFA:PUFA, p = 0.005) and total n-3 PUFA (p = 0.001) were significantly higher in ORE eggs.5. The n-3:n-6 ratio was significantly impacted by treatment (p = 0.021) and storage (p = 0.031) with no significant interaction. This ratio is important for human health indication and could lead to the development of designer eggs.

Association of keel bone morphometry with keel bone damage and skeletal quality in the laying hen.

1. The aim of this work was to identify a heritable keel bone phenotype with a correlation to keel bone damage and/or skeletal bone strength that could be easily measured in the living hen to aid selection to prevent welfare issues.2. The scoring system used reflected the observed damage, keel bone dimensions and shape compared to traditional measurements of bone quality.3. Increased keel bone damage was associated with poor humerus and tibia breaking strengths (p < 0.01). Bone damage was associated with higher whole keel density (p < 0.01) due to the effect of callus formation.4. Keel bone depth and area was moderately heritable at indices of 0.32 and 0.40, respectively. Keel bone depth was genetically correlated with tibia (0.36) and humerus density (0.68) and keel bone area was correlated with humerus density (0.59). Deeper keel bones and those with larger areas had small, negative phenotypic correlations with keel bone damage (-0.07 and -0.11, respectively). The second principal component of keel bone shape represented the caudal section of the keel bone and cranial edge concavity. The third principal component represented the differences in the caudal tip of the keel bone, the concavity of the dorsal edge and convexity of the ventral edge. Heritability estimates were 0.44 and 0.39, respectively.5. The results suggested that genetics contribute to morphometric traits. Hens with poorer skeletal quality are likely to accumulate more damage. Some of the traits may be a predictor of damage, although mid keel depth or concavity may simply reflect the effect of damage or deviation.

Dietary stinging nettle (Urtica dioica) improves carotenoids content in laying hen egg yolk.

1. This study assessed the addition of dried stinging nettle (SN) leaves at 0%, 2.5% and 5.0% in feed on egg production, egg quality, chemical composition and antioxidant content in eggs from laying hens.2. Seventy-two Hy-Line Brown laying hens, housed in 36 enriched layer cages, were used in the study from 43 to 47 weeks of age. Feeding dry SN leaves did not affect (p > 0.05) egg production variables.3. Dietary SN inclusion linearly increased (p < 0.001) carotenoid content more than six-fold, in addition to yellowness and redness of the yolks at the maximum inclusion. Providing eggs from hens fed carotenoid enriched diets, e.g. SN, may be used to increase carotenoids in human diets.

Partial budget analysis of laying hens' transition from cages to production systems of improved welfare: a case study in Greece.

1. In recent years, public concern regarding animal welfare has increased while, at the same time, cage systems for animal production have been greatly criticised by EU citizens. In addition, large food retailers promote food products that are made with eggs produced in cage-free systems.2. The objective of this study was to evaluate the economic viability of the transition of laying hens' to production systems; from conventional to alternative systems with improved welfare. Three independent scenarios were assumed as follows: transition from enriched colony cages to barn (S1), transition from barn to free-range (S2), and transition from free-range to organic (S3). Economic assessments of each transition was applied to a model farm in Greece with 12 000 hens, through partial budget analysis and net benefits and costs were estimated.3. The results showed a positive economic impact in all transitions to a production system of improved animal welfare (€12,044 in S1, €18,957 in S2 and €7,977 in S3) which indicated that they are economically sustainable. In all scenarios, unit cost increased by 19% in S1, 12% in S2, and 85% in S3.4. In conclusion, transitioning towards improved animal welfare production systems in laying hen farms could be an economically viable option for egg producers in compliance with societal demands and market trends.

Effect of different levels of single cell protein and probiotic microorganisms on performance, immunological responses, and intestinal histology in laying hens.

An experiment was conducted to evaluate the effects of single-cell protein (SCP), as a valuable by-product and substitute for soybean meal, and multistrain probiotics on the performance, blood biochemistry, intestinal histomorphology, ileal microbiota, and immune responses in laying hens. Leghorn laying hens were randomly assigned to nine experimental treatments with eight replicates of five birds each. Dietary treatments consisted of three levels of replacement of soybean meal with SCP (0.0%, 30%, and 60%) and three levels of probiotics (0.0, 50, 100 mg/kg) offered through 70 days of main recording. The result indicated that replacing 30% soybean meal with SCP in the diet significantly increased the eggshell weight, thickness, and strength; however, hens receiving 60% SCP replacement showed lower productive performance. During the second 35-d trial, hens receiving at least 50 mg/kg probiotics produced higher eggshell weight, thickness, and strength than the control hens. Remarkable lower levels of serum cholesterol content were observed in the SCP and probiotic-supplemented diets. The significant reduction in the ileal pH, Escherichia coli and Clostridium spp. enumerations and a remarkable increase in Lactobacillus count was observed after feeding incremental levels of probiotics. The highest villus height to crypt depth ratio, antibody titer against sheep red blood cells (in secondary response) and Newcastle disease vaccine, as well as egg production and egg mass, were found in the hens that received 30% SCP replacement in combination with 50 or 100 mg/kg probiotic (SCP × Probiotic). The present study concluded that feeding SCP, as a cheap protein alternative source, along with probiotics while reducing production costs can support productive performance via modulating the intestinal microbiomes and health indices and fortifying the immune system in laying hens.

Meta-Analysis of Positive Effects of Dietary Turmeric (Curcuma longa L.) on Performance of Commercial Laying Hens.

Turmeric improves performance in nonruminants, but results in laying hens are not consistent. This meta-analysis assessed the performance of laying hens fed turmeric powder (TP)-based diets. Nineteen studies retrieved from Google Scholar, Scopus, ScienceDirect, PubMed, and Web of Science databases were used for the meta-analysis. The outcome variables analysed were productive indices (feed intake [FI], feed conversion ratio [FCR], hen day production [HDP], egg weight [EW], egg mass [EM]), egg quality (Haugh unit [HU], shell thickness [SHT], shell strength [SHS], yolk cholesterol [YC]), serum biochemical parameters (serum cholesterol [SC], alanine transferase [ALT], and aspartate transferase [AST]), and moderator variables (layer strains, inclusion level, feeding duration, and hen's age). All analyses were performed on OpenMEE software and the R package. A random-effects model (REM) was used and results were presented as standardised mean difference (SMD) at a 95% confidence interval (CI). The results showed that dietary TP improved FCR (SMD = -0.31; 95% CI: -0.61, -0.01; p = 0.046) and HDP (SMD = 0.49; 95% CI: 0.29, 0.69; p < 0.001), but not EW, EM, HU, SHT, SHS, YC, and serum AST in layers. On the other hand, dietary TP decreased FI (SMD = -0.15; 95% CI: -0.26, -0.05; p = 0.004), SC (SMD = -75.18; 95% CI: -102.55, -47.80; p < 0.001), and ALT (SMD = -3.55; 95% CI: -4.71, -2.40; p < 0.001) in laying hens with proof of significant heterogeneity. However, meta-regression showed that layer strains and feeding duration accounted for most of the sources of heterogeneity. In conclusion, results suggest that dietary TP increased HDP and reduced FI, FCR, SC, and ALT in laying hens.