Microbiota continuum along the chicken oviduct and its association with host genetics and egg formation

Eggshell depigmentation in the late phase of production is associated with altered Microbiota and Metabolism of the uterus in laying hens

The significant depigmentation of brown eggshells occurs in the in the late-phase laying hens, which directly affects consumer acceptance. However, the biological mechanism of eggshell depigmentation based on uterine metabolism has not been elucidated. In this study, a total of 4 group were as follows: 1) 65-week-old laying hens with normal color; 2) 65-week-old laying hens with light color; 3) 80-week-old laying hens with normal color; 4) 80-week-old laying hens with light color. Variations in the pigment contents, uterine antioxidant capacity, uterine microbiota, and uterine metabolomics were examined in current study. Results showed that significantly decreased L* values and increased a* and b* values were observed in the depigmentation group (P < 0.05). The protoporphyrin IX content of the uterus with eggshell depigmentation was significantly decreased in 65-week-old laying hens (P < 0.05). Uterine MDA content was significantly increased in the depigmentation groups at 65 and 80 weeks of age, accompanied by reduced SOD and increased IgA levels (P > 0.05). The abundance of Proteobacteria and Campilobacterota was markedly reduced in the uterus with eggshell depigmentation, whereas Firmicutes was elevated at 65 weeks of age (P < 0.05). Further, Psychrobacte as biomarkers can accurately distinguish between normal color and depigmentation in eggshells (AUC = 0.91). A total of 51 differential metabolites were significantly enriched in the down-regulated sphingolipid metabolism, linoleic acid metabolism, citrate cycle, oxidative phosphorylation, PPAR signaling pathway, FoxO signaling pathway, and apoptosis at 65 weeks of age (P < 0.05). Meanwhile, there were 82 differential metabolites were significantly up-regulated at 80 weeks of age, which mainly enriched in up-regulated linoleic acid metabolism, purine metabolism, and pentose phosphate pathway (P < 0.05). These findings elucidate the specific metabolic mechanisms responsible for eggshell depigmentation in 65- and 80-week-old laying hens, contributing to the improvement of eggshell depigmentation by the precise nutritional modulation in the late-phase laying hens.

Brown-shell eggs shows high incidence of blood and meat spots accompanied by unique microbial distribution patterns

Introduction

The blood and meat spots in eggs are recognized as defects for egg quality. The frequency of blood and meat spots in brown-shell eggs is much higher than that in white-shell eggs in previous studies. However, the actual occurrence frequency and their effects on the microbial composition in eggs remain poorly understood.

Methods

In this study, we examined the frequency of blood and meat spots in brown-shell and white-shell eggs, respectively, from Rhode Island Red and White Leghorn chickens at seven ages.

Results

The results showed that blood and meat spots in brown-shell eggs exhibit much higher average frequency (63.99%) than that in white-shell eggs (1.37%). Furthermore, we analyzed the relationship between the presence of blood and meat spots and the microbial community distribution in the egg albumen and yolk. Briefly, we selected brown-shell eggs (n = 112) from Rhode Island Red, among which 51 eggs showing blood/meat spots were classified as RIR_CASE, and 61 normal eggs without blood/meat spot were classified as RIR_CON. Additional white-eggshell eggs (n = 124) without blood/meat spots from White Leghorn were selected as WL_CON. 16S rRNA sequencing was performed in both egg white and yolk. The results indicated that neither egg white nor yolk is sterile, with Proteobacteria identified as the dominant bacterial phyla. The microbial alpha diversity in both egg white and yolk of RIR_CASE was significantly lower compared to RIR_CON and WL_CON. Beta diversity analysis showed that the Weighted UniFrac Distance between RIR_CASE and RIR_CON in the egg yolk group was significantly larger than the distance between WL_CON and RIR_CON. It suggested that the difference of microbial diversity was mainly caused by blood and meat spots other than by chicken breeds. LEfSe analysis identified eight microbial taxa closely linked to the presence of blood and meat spots in egg white or yolk. Moreover, through the combination of random forest analysis, we identified the unique microbial biomarkers Comamonas_F and Chryseobacterium in the egg white of the RIR_CASE group.

Discussion

Our study indicates that eggs with blood and meat spots occur at a higher frequency in brown-shell chickens and are accompanied by a distinct microbial community distribution.

Kaempferol and Vitamin E Improve Production Performance by Linking the Gut-Uterus Axis Through the Reproductive Hormones and Microbiota of Late-Laying Hens

This study evaluated the effects of kaempferol (KAE), and vitamin E (VE) on the performance, reproductive hormones, and the composition of the cecum and uterus microbiota in late-laying hens. A total of 192 49-week-old Jinghong No. 1 laying hens were randomly divided into four groups, with six replicates in each group and eight laying hens in each replicate, pre-reared for one week and formally tested for ten weeks. The CON group was fed basal diets, the VE group, the KAE group, and the KAE + VE group were fed a basal diet to which was added 0.2 g/kg VE, 0.4 g/kg KAE, and 0.2 g/kg VE + 0.4 g/kg KAE, respectively. The results are as follows. Compared to the CON group, the VE group, the KAE group, and the KAE + VE group significantly increased the egg production rate, average daily egg weight and significantly decreased the feed-to-egg ratio. The VE + KAE group significantly improved the Haugh unit. The VE group, the KAE group, and the KAE + VE group considerably enhanced the eggshell strength, eggshell relative weight, eggshell thickness, yolk color, and relative yolk weight. The serum E2 and LH levels of the KAE group and the KAE + VE group and the serum FSH levels of the KAE + VE group were significantly higher. In the ovary, the KAE group and the KAE + VE group's ESR1 gene expression levels were significantly higher, and the KAE + VE group's FSHR gene expression levels were markedly higher. In the uterus, the KAE group and the KAE + VE group's ESR1 gene expression levels were dramatically higher, and the KAE + VE group's ESR2 and FSHR gene expression levels were significantly higher. 16S rRNA gene sequencing revealed a significant aggregation of cecum and uterus colonies in the Beta diversity PCoA. In the cecum, Firmicutes, Bacteroidetes, and WPS-2 were the dominant phylums. In the uterus, the Firmicutes, Proteobacteria, and Bacteroidetes were the dominant phylums. The KAE + VE group's F/B was significantly higher at the phylum level than in the CON group and the VE group. In summary, the addition of VE and KAE to the diet can improve the production performance of late-laying hens, increase the content of reproductive hormones, and stabilize the cecal and uterus microbiota, which may be related to the hormone and microbiota linkage of the gut-uterus axis.

Research Note: Correlation between the reproductive tract microbiota and speckled eggs in laying hens

The microbiomes of the reproductive tract play a crucial role in the egg production and quality and reproductive health of laying hens. Speckled eggs are characterized by shells with brown spots of varying sizes and commonly produced by brown-shelled laying hens. Speckles reduce the economic value of eggs. However, the relationship between oviduct and cloacal microbiomes and the presence of speckled eggs in laying hens remains unclear. In this study, we collected samples from the reproductive tracts (uterus, vagina, and cloaca) of hens laying speckled eggs and those laying normal eggs and compared their microbial structures and relative abundances through 16S rRNA sequencing. We found that the microbial community structure in the reproductive tracts of the hens laying speckled eggs was similar to that in the reproductive tracts of the hens laying normal eggs; however, the relative abundances of Clostridium in the uterus and Turicibacter and Gallibacterium in the vagina of the hens from the speckled group (7.27%, 6.83% and 0.10%, respectively) were significantly higher than those in the normal group (2.00%, 0% and 0%, respectively [P < 0.05]). Additionally, 8, 24, and 11 bacterial taxa in the uterus, vagina, and cloaca were different between the groups of hens laying speckled and normal eggs. At the same time, Clostridium in the uterus may be associated with eggshell speckles. However, further investigations are necessary to understand the functions of these microbiota in the reproductive tracts of laying hens. This study provides novel insights into methods for reducing the occurrence of speckled eggs in laying hens.

Lactobacillus crispatus-Mediated Gut-Reproductive Tract Axis-Alleviated Microbial Dysbiosis and Oviductal Inflammation in a Laying Hen Model

Oviductal inflammation (OI) significantly reduces the egg production and economic returns in poultry farming. While Lactobacillus crispatus (LAC) is effective against inflammation, its role in treating or preventing oviductal inflammation is understudied. In this study, we investigated the therapeutic mechanisms of LAC on oviductal inflammation, with a focus on reproductive tract health, microbiome, gene expression, and cytokine levels. This study involved 24 Jingfen No. 6 laying hens aged 60 weeks, divided into four groups: the CON, OI, OI + LAC, and OI + heat-killed Lactobacillus crispatus (HLAC) groups. And it included a 10-day adaptation, a 7-day period for the development of OI using inflammation-inducing drugs (the control received saline), followed by an 8-day treatment in which the CON and OI groups received 1 mL of MRS broth daily, and the OI + LAC and OI + HLAC groups were treated with live and heat-killed Lactobacillus crispatus (109 CFUs/mL), respectively, with six hens in each group. This study showed that Lactobacillus crispatus supplementation significantly reduced the oviductal inflammation and atrophy in the hens, with the affected hens showing markedly lower egg production rates (p < 0.001) compared to the control and treated groups (OI + HLAC and OI + LAC). The daily intake of fresh (OI + LAC, p = 0.076) or heat-killed (OI + HLAC, p < 0.01) Lactobacillus crispatus notably enhanced the feed conversion efficiency. The OI group suffered significant ovarian damage and vascular rupture, more so than the CON group, while Lactobacillus crispatus supplementation mitigated this damage. The IL-1β, IL-6, and IL-8 levels were significantly elevated in the OI group compared to those in the OI + LAC group (p < 0.05), with a significant reduction in the TNF-α levels in the latter (p < 0.001). The supplementation improved the microbial composition in the cecum, isthmus, and shell gland, enriching the cecum with beneficial bacteria, such as Ruminococcus_torques_group and Megamonas. This approach fostered ovarian health and follicle differentiation and preserved the epithelial cell barrier function in the shell gland, reducing inflammatory damage in the genital tract. This dual efficacy underscores the role of the probiotic in diminishing oviductal inflammation, regardless of its state.

Research Note: Analysis of microbial diversity on the shell surface of eggs collected from geographically distinct farms in China

Micro-organisms on the eggshell surface of affect the quality of the egg. Sometimes, these microbes even pose a serious threat to the health of the egg's consumer. Bacterial 16S rDNA and fungal internal transcribed spacer region were sequenced to analyze the microbial diversity on the shell surface of the eggs collected from 4 distinct regions of China: Guyuan (GY; 1.5 million hens), Langfang (LF; 0.1 million hens), Beihai (BH; 1.2 million hens), and Dongguan (DG; 0.2 million hens). The results showed a higher bacterial and fungal abundance on the eggs collected from the northern and southern China farms, respectively. The dominant bacterial phylum detected across all egg samples was Firmicutes. In addition, the shell surfaces of the DG and LF samples harbored abundant levels of Proteobacteria. The dominant fungal phyla detected across all egg samples were Ascomycota and Basidiomycota. The bacterial compositions on eggshell surfaces differed significantly across all geographic regions, and the fungal composition differed significantly between samples collected from the southern and northern farms (P < 0.05). The abundance and composition of microbial colonies on the eggshell surface varied based on their geographical location (climate and environment) and farming scale (management). Our findings provide an important reference for optimizing the cleaning and disinfection methods for fresh eggs collected from different sources.

Comparative analysis of reproductive tract microbiomes in modern and slower-growing broiler breeder lines

Introduction

The reproductive tract microbiome in hens is of interest because bacteria in the reproductive tract could potentially affect fertilization and egg production, as well as integrate into the forming egg and vertically transmit to progeny.

Methods

The reproductive tract microbiome of 37-week-old modern commercial Cobb breeding dams was compared with that of dams from a broiler Legacy line which has not undergone selection since 1986. All animals were kept together under the same management protocol from day of hatch to avoid confounders.

Results

In regards to reproductive abilities, Cobb dams' eggs weighed more and the magnum section of their reproductive tract was longer. In regards to microbiome composition, it was found that the reproductive tract microbiomes of the two lines had a lot in common but also that the two breeds have unique reproductive tract microbiomes. Specifically, the order Pseudomonadales was higher in the magnum of Legacy dams, while Verrucomicrobiales was lower. In the infundibulum, Lactobacillales were higher in the Legacy dams while Verrucomicrobiales, Bacteroidales, RF32 and YS2 were lower.

Discussion

our results show that breeding programs have modified not only the physiology of the reproductive tract but also the reproductive tract microbiome. Additional research is required to understand the implications of these changes in the reproductive tract microbiome on the chicken host.

Comamonas testosteroni as the cause of mortality in embryonated chicken eggs of breeding broiler hens in Costa Rica

Mortality of chicken embryos and first-week chickens was reported in a commercial incubator company in Costa Rica. Six 1-day-old Cobb chickens and twenty-four embryonated chicken eggs were examined in the Laboratory of Avian Pathology and the Laboratory of Bacteriology of the National University of Costa Rica. Twelve dead-in-shell embryos showed maceration and were immersed in a putrid, turbid, slightly thick brown liquid. Additionally, the other 12 embryonated eggs had milky yellow-orange content. The livers of those embryos had congestion, haemorrhages and multifocal cream foci of necrosis. Granulocytic infiltration was observed in the bursa of Fabricius, myocardium, liver, lung and kidney. Livers and egg yolks from six embryonated chickens and all 1-day-old chickens were aseptically collected and cultured. In addition, tissues from six better conserved embryos and all 1-day-old chickens were fixed in buffered formalin and embedded in paraffin. Biochemical and molecular tests identified Comamonas testosteroni as the cause of the early, middle and late embryo mortality. As all the eggshells from the sampled embryonated eggs were dirty with soiled a fecal matter, contamination after manipulating the eggs was considered the source of infection. C. testosteroni is an environmental microorganism that has rarely been reported to cause human disease. To our knowledge, this is the first report of C. testosteroni causing mortality in a hatchery. Cleaning and disinfection using ozone were implemented in the hatchery to eliminate the embryo mortality associated with C. testosteroni.

The improvement of immunity and activation of TLR2/NF-κB signaling pathway by Romboutsia ilealis in broilers

This study was conducted to investigate the effects of Romboutsia ilealis on the immune function of broilers and the underlying mechanisms. A total of 48 one-day-old Arbor Acres broilers were allocated to 4 groups as follows: broilers treated daily with 1 mL live R. ilealis in general anaerobic medium broth media (0, 1 × 104, 1 × 106, and 1 × 108 CFU/mL) from days 1 to 7. Samples were collected on days 8 and 14. The results showed that R. ilealis had no negative effect on the body weight of broilers (P > 0.05). R. ilealis significantly increased the levels of lysozyme, IFN-γ, IFN-γ/IL-4, and IgG in the serum (P < 0.05). R. ilealis significantly increased the levels of IL-4, IFN-γ, sIgA, lysozyme, and iNOS in the ileal mucosa (P < 0.05). R. ilealis significantly increased the mRNA levels of TLR2, TLR4, NF-κB, IL-1β, TNF-α, IFN-γ, IgA, pIgR, iNOS, and MHC-II in the ileum (P < 0.05). R. ilealis significantly increased the relative abundance of Enterococcus and Paracoccus in the jejunum and ileum, ileal Candidatus Arthromitus, and cecal Romboutsia and Intestinimonas (P < 0.05). Correlation analysis showed that Enterococcus, Paracoccus, Romboutsia, and Intestinimonas were significantly positively correlated with humoral immune function (P < 0.05). In conclusion, R. ilealis boosted the immune system, activated the intestinal TLR2/NF-κB signaling pathway, and improved the gut microbiota in broilers.

Uterine microbial communities and their potential role in the regulation of epithelium cell cycle and apoptosis in aged hens

BACKGROUND

Alterations of the uterine microbiome are closely associated with various intrauterine diseases and physiological conditions, which are well-established in mammals. However, as representative oviparous animals, the research on the uterine microbial ecosystem and its functions with physiological homeostasis is limited in chickens. Additionally, continuous egg-laying disrupts the oviducal immune defenses of aged hens, susceptible to pathogen invasion, causing poor egg quality and food-borne infections in humans. Here, we investigated aging-related changes in the oviduct microbial colonization and transmission from the gut to eggs and their roles in a hen model.

RESULTS

The results of 16S rDNA sequencing showed significant differences in the oviduct microbial composition between young (38 weeks) and aged (77 weeks) laying hens. SourceTracker analysis further revealed differences in the effects of microbial transmission on the oviducal microbiota between young and aged hens. Enhanced barrier defense with cell apoptosis suppression and cell cycle arrest of the uterus were observed in aged hens reducing microbial transmission from the lower to upper reproductive tract. In addition, a total of 361 significantly differential metabolites were identified using metabolomics in the aged uterine microbiota, especially in products of amino acid metabolism and biosynthesis of various secondary metabolites, which might have essential effects on cell apoptosis by regulating immune responses and cell cycle. Notably, antibiotics disrupted uterine microbiota by dietary intervention and direct perfusion did not retard aging-related physiological changes but further aggravated aging processes by disrupting the cell cycle and apoptosis.

CONCLUSIONS

The microbiota continuum along the reproductive tract in aged birds differs from that in young birds, especially with a significant shift in the uterus. The aged uterine microbiota probably contributes to the regulation of cell cycle and apoptosis by microbial metabolites primarily involved in amino acid metabolism and biosynthesis of various secondary metabolites. These findings provide new insights into the roles of the reproductive tract microbiota in regulating the cell programming of the aged host, contributing to the exploration of the microbiome as a target for diagnosing aging health status and therapy for gynecological diseases in women. Video Abstract.

Microbiota Profiles of Hen Eggs from the Different Seasons and Different Sectors of Shanghai, China

Hen eggs are one of the most popular foods worldwide, and their safety is critical. Employing 16S rRNA full-length sequencing is an effective way to identify microorganisms on or in eggs. Here, hen eggs collected from poultry farms over four seasons, as well as from markets in Shanghai, were analyzed with third-generation sequencing. Firmicutes (44.46%) and Proteobacteria (35.78%) were the two dominant phyla, and Staphylococcus, Acinetobacter, Aerococcus, Psychrobacter, and Lactobacillus were the dominant genera. The dominant genera on the eggshell surfaces from the farms varied with the seasons, and the highest contamination of Staphylococcus (32.93%) was seen in the eggs collected during the summer. For the market samples, Pseudomonas was the most abundant in content, with Staphylococcus being the most-often genera found on the eggshell surfaces. Moreover, several potential pathogenic bacteria including Riemerella anatipestifer (species), Klebsiella (genus), and Escherichia/shigella (genus) were detected in the samples. The results revealed the impacts of weather on the microbiota deposited on an eggshell's surface, as well as the impacts due to the differences between the contents and the surface. The results can help disinfect eggs and guide antibiotic selection.

Effects of tea residues-fermented feed on production performance, egg quality, antioxidant capacity, caecal microbiota, and ammonia emissions of laying hens

This study was to assess the effects of tea residues-fermented feed (TR-fermented feed) on production performance, egg quality, serum antioxidant capacity, caecal microbiota, and ammonia emissions of laying hens. A total of 1,296 Lohmann laying hens have randomly distributed four groups with six parallels and fed with diets TR-fermented feed at the rates of 0 (control), 1, 3, and 5%. The inclusion of 1% (TR)-fermented feed resulted in a significant increase in egg-laying rate and average egg weight of birds, and a reduction in the feed-to-egg ratio when compared to the control group (p < 0.05). The addition of 1 and 3% of (TR)-fermented feed significantly improved the Haugh unit of eggs (p < 0.05). The eggshell thickness was observed to increase by almost one-fold upon the inclusion of 3 and 5% (TR)-fermented feed in the basal diet (p < 0.05). The supplementation of 3% (TR)-fermented feed significantly increased the content of methionine, tyrosine, proline, essential amino acids (EAA), alpha linoleic acid (C18:3n6), docosanoic acid (C22:0), docosahexaenoic acid (C22:6n3), twenty-three carbonic acids (C23:0), ditetradecenoic acid (C24:1) and total omega-3 polyunsaturated fatty acids (∑ω-3 PUFA) in the eggs (p < 0.05). The addition of a certain amount of (TR)-fermented feed can enhance the activity of glutathione peroxidase (GSH-PX) and superoxide dismutase (SOD) in chicken serum, and reduce the level of malondialdehyde (MDA) (p < 0.05). The ammonia concentration in the hen house of laying hens in the treatment groups decreased significantly (p < 0.05). Bacteroidetes and Firmicutes, the main phyla in the cecal bacterial community, were differentially abundant in each group, comprising greater than 55 and 33%, respectively. Collectively, this research indicates that (TR)-fermented feed supplementation improves the performance of laying hens and reduces ammonia emissions and can be used in industry-scale layer production.

Maternal effects drive intestinal development beginning in the embryonic period on the basis of maternal immune and microbial transfer in chickens

BACKGROUND

Nutrition drives immunity and health in animals, and maternal immunity benefits offspring. In our previous study, a nutritional intervention strategy was found to promote the immunity of hens, which subsequently improved immunity and growth in offspring chicks. Maternal effects clearly exist, but how are mothers' immune advantages transferred to their offspring, and how do they benefit them?

RESULTS

Here, we traced the beneficial effects back to the process of egg formation in the reproductive system, and we focused on the embryonic intestinal transcriptome and development, as well as on maternal microbial transfer in offspring. We found that maternal nutritional intervention benefits maternal immunity, egg hatching, and offspring growth. The results of protein and gene quantitative assays showed that the transfer of immune factors into egg whites and yolks depends on maternal levels. Histological observations indicated that the promotion of offspring intestinal development begins in the embryonic period. Microbiota analyses suggested that maternal microbes transfer to the embryonic gut from the magnum to the egg white. Transcriptome analyses revealed that offspring embryonic intestinal transcriptome shifts are related to development and immunity. Moreover, correlation analyses showed that the embryonic gut microbiota is correlated with the intestinal transcriptome and development.

CONCLUSIONS

This study suggests that maternal immunity positively influences offspring intestinal immunity establishment and intestinal development beginning in the embryonic period. Adaptive maternal effects might be accomplished via the transfer of relatively large amounts of maternal immune factors and by shaping of the reproductive system microbiota by strong maternal immunity. Moreover, reproductive system microbes may be useful resources for the promotion of animal health. Video Abstract.

The Role of Biofilms in the Pathogenesis of Animal Bacterial Infections

Biofilms are bacterial aggregates embedded in a self-produced, protective matrix. The biofilm lifestyle offers resilience to external threats such as the immune system, antimicrobials, and other treatments. It is therefore not surprising that biofilms have been observed to be present in a number of bacterial infections. This review describes biofilm-associated bacterial infections in most body systems of husbandry animals, including fish, as well as in sport and companion animals. The biofilms have been observed in the auditory, cardiovascular, central nervous, digestive, integumentary, reproductive, respiratory, urinary, and visual system. A number of potential roles that biofilms can play in disease pathogenesis are also described. Biofilms can induce or regulate local inflammation. For some bacterial species, biofilms appear to facilitate intracellular invasion. Biofilms can also obstruct the healing process by acting as a physical barrier. The long-term protection of bacteria in biofilms can contribute to chronic subclinical infections, Furthermore, a biofilm already present may be used by other pathogens to avoid elimination by the immune system. This review shows the importance of acknowledging the role of biofilms in animal bacterial infections, as this influences both diagnostic procedures and treatment.

Microbial composition of egg component and its association with hatchability of laying hens

The internal quality of eggs is critical for human consumption and embryonic development. However, microorganisms inside eggs have not been thoroughly investigated for their roles in determining the egg's internal quality. Here, a total of 21 hens were selected from more than 1,000 chickens based on their hatching results and were divided into high- and low-hatchability groups. Then, we collected 72 eggs from these 21 hens to obtain egg whites and yolks, including 54 fresh eggs and 18 eggs after 12 days of incubation. We characterized the microbial composition of egg yolks and whites, the microbial change along incubation, and differences in microbial abundance between the high- and low-hatchability groups. The results indicated that egg whites are not sterile. Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes were the dominant phyla in egg yolk and white. There was a large difference in the microbial composition between egg whites and yolks, and this difference increased after 12 days of incubation. Egg whites have lower microbial diversity than egg yolks owing to the presence of antibacterial substances such as lysozyme in the egg white. After a 12-day incubation, the microbial diversity decreased in egg whites but increased slightly in egg yolks. Meanwhile, the microbes in egg white can migrate to egg yolk during incubation. Additionally, Genus Muribaculaceae was identified as a biomarker in egg yolks incubated for 12 days and was more often detected in healthy groups. On the contrary, more genus Rothia were found in the fresh egg yolk of the low hatchability groups and was considered to have low virulence. These findings shed light on the composition and differences in microbiota between egg yolks and whites and may open new avenues for studying embryonic development in chickens.

Bacterial communities of the oviduct of turkeys

Bacterial communities in the reproductive tract of avian species play an important role in keeping birds healthy and encouraging growth. Infection can occur during egg formation with pathogens that can be transmitted to the embryo. In this study, we investigated the bacterial composition in the turkey reproductive tract using a taxa identification based on the amplicon sequence of the V3–V4 region of the 16S rRNA gene. The microbial composition and relative abundance of bacteria differed between individual birds. Among the 19 phyla detected in turkey oviduct were unique taxa like Planctomycetes or Petescibacteria. Differences in composition of bacterial diversity were found at the family and genus level. Oviducts contained also several genus with well-recognized avian pathogens like Escherichia-Shigella, Enterococcus, Staphylococcus, and Ornithobacterium. Some of the bacteria described in this study have not been so far identified in turkeys. The objective of this study was to identify bacterial communities in the turkey oviduct and compared the composition of the oviduct with that in chickens broadening the knowledge of the microbial composition in the reproductive tract of poultry.

Delayed access to feed early post-hatch affects the development and maturation of gastrointestinal tract microbiota in broiler chickens

Background

The first two weeks of post-hatch (PH) growth in broilers (meat-type birds) are critical for gut development and microbiota colonization. In the current broiler production system, chicks may not receive feed and water for 24 to 72 h due to variations in hatching time and hatchery management. Post-hatch feed delay affects body weight, feed efficiency, mortality, and gut development. The goal of this study was to investigate changes in the microbiome in broiler chickens early PH and the effect of delayed access to feed on the microbiota.

Results

Chicks either received feed and water immediately after hatch or access to feed was delayed for 48 h to mimic commercial hatchery settings (treatment, TRT). Both groups were sampled (n = 6) at -48, 0, 4 h, and 1 (24 h), 2 (48 h), 3 (72 h), 4 (96 h), 6 (144 h), 8 (192 h), 10 (240 h), 12 (288 h) and 14 (336 h) days PH. Ileal (IL) and cecal (CE) epithelial scrapings (mucosal bacteria, M) and digesta (luminal bacteria, L) were collected for microbiota analysis. Microbiota was determined by sequencing the V3-V4 region of bacterial 16S rRNA and analyzed using QIIME2. The microbiota of early ileal and cecal samples were characterized by high abundance of unclassified bacteria. Among four bacterial populations (IL-L, IL-M, CE-L, CE-M), IL-M was the least affected by delayed access to feed early PH. Both alpha and beta diversities were affected by delayed access to feed PH in IL-L, CE-M and CE-L. However, the development effect was more pronounced. In all four bacterial populations, significant changes due to developmental effect (time relative to hatch) was observed in taxonomic composition, with transient changes of bacterial taxa during the first two weeks PH. Delayed access to feed has limited influence on bacterial composition with only a few genera and species affected in all four bacterial populations. Predicted function based on 16S rRNA was also affected by delayed access to feed PH with most changes in metabolic pathway richness observed in IL-L, CE-L and CE-M.

Conclusions

These results show transient changes in chicken microbiota biodiversity during the first two weeks PH and indicate that delayed access to feed affects microbiota development. Proper microbiota development could be an important factor in disease prevention and antibiotic use in broiler chickens. Moreover, significant differences in response to delayed access to feed PH between luminal and mucosal bacterial populations strongly suggests the need for separate analysis of these two populations.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-022-02619-6.

Intestinal microbiota of layer hens and its association with egg quality and safety

The intestinal microbiota has attracted tremendous attention in the field of the poultry industry due to its critical role in the modulation of nutrient utilization, immune system, and consequently the improvement of the host health and production performance. Accumulating evidence implies intestinal microbiota of laying hens is a potential mediator to improve the prevalent issues in terms of egg quality decline in the late phase of laying production. However, the regulatory effect of intestinal microbiota on egg quality in laying hens remains elusive, which requires consideration of microbial baseline composition and succession during their long lifespans. Notable, although Firmicutes, Bacteroidetes, and Proteobacteria form the vast majority of intestinal microbiota in layer hens, dynamic intestinal microbiota succession occurs throughout all laying periods. In addition to the direct effects on egg safety, intestinal microbiota and its metabolites such as short-chain fatty acids, bile acids, and tryptophan derivatives, are suggested to indirectly modulate egg quality through the microbiota-gut-liver/brain-reproductive tract axis. These findings can extend our understanding of the crosstalk between intestinal microbiota and the host to improve egg quality and safety. This paper reviews the compositions of intestinal microbiota in different physiological stages of laying hens and their effects on egg quality and proposes that intestinal microbiota may become a potential target for modulating egg quality and safety by nutritional strategies in the future.

Multi-Omics Analysis After Vaginal Administration of Bacteroides fragilis in Chickens

The reproductive tract of chickens is an important organ for egg formation. The vagina is in close contact with the external environment, which may lead to the invasion of a variety of pathogenic bacteria, affect the internal and external quality of eggs, and even increase mortality and cause economic loss. In recent years, probiotics as a substitute for antibiotics have brought economic benefits in livestock and poultry production. In the present study, we investigated the effects of vaginal administration of Bacteroides fragilis on the cloacal microbiota, vaginal transcriptome and metabolomics of chickens and evaluated the beneficial potential of B. fragilis. The results showed that B. fragilis treatment could affect the microbial composition of the cloaca. Transcriptome analysis found that the immune-related genes CCN3, HAS2, and RICTOR were upregulated, that the inflammatory genes EDNRB, TOX, and NKX2-3 were downregulated, and that DEGs were also enriched in the regulation of the inflammatory response, cellular metabolism, and synaptic response pathways. In addition, the differential metabolites were mainly related to steroid hormone biosynthesis, unsaturated fatty acid biosynthesis, and arachidonic acid metabolism, and we identified associations between specific differential metabolites and genes. Overall, this study provides a theoretical basis for the application of B. fragilis as a potential probiotic in livestock and poultry production.

Properties, Genetics and Innate Immune Function of the Cuticle in Egg-Laying Species

Cleidoic eggs possess very efficient and orchestrated systems to protect the embryo from external microbes until hatch. The cuticle is a proteinaceous layer on the shell surface in many bird and some reptile species. An intact cuticle forms a pore plug to occlude respiratory pores and is an effective physical and chemical barrier against microbial penetration. The interior of the egg is assumed to be normally sterile, while the outer eggshell cuticle hosts microbes. The diversity of the eggshell microbiome is derived from both maternal microbiota and those of the nesting environment. The surface characteristics of the egg, outer moisture layer and the presence of antimicrobial molecules composing the cuticle dictate constituents of the microbial communities on the eggshell surface. The avian cuticle affects eggshell wettability, water vapor conductance and regulates ultraviolet reflectance in various ground-nesting species; moreover, its composition, thickness and degree of coverage are dependent on species, hen age, and physiological stressors. Studies in domestic avian species have demonstrated that changes in the cuticle affect the food safety of eggs with respect to the risk of contamination by bacterial pathogens such as Salmonella and Escherichia coli. Moreover, preventing contamination of internal egg components is crucial to optimize hatching success in bird species. In chickens there is moderate heritability (38%) of cuticle deposition with a potential for genetic improvement. However, much less is known about other bird or reptile cuticles. This review synthesizes current knowledge of eggshell cuticle and provides insight into its evolution in the clade reptilia. The origin, composition and regulation of the eggshell microbiome and the potential function of the cuticle as the first barrier of egg defense are discussed in detail. We evaluate how changes in the cuticle affect the food safety of table eggs and vertical transmission of pathogens in the production chain with respect to the risk of contamination. Thus, this review provides insight into the physiological and microbiological characteristics of eggshell cuticle in relation to its protective function (innate immunity) in egg-laying birds and reptiles.

Recovered microbiome of an oviparous lizard differs across gut and reproductive tissues, cloacal swabs, and faeces

Microbial diversity and community function are related, and can be highly specialized in different gut regions. The cloacal microbiome of Sceloporus virgatus females provides antifungal protection to eggshells, a specialized function that suggests a specialized microbiome. Here, we describe the cloacal, intestinal, and oviductal microbiome from S. virgatus gravid females, adding to growing evidence of microbiome localization in reptiles and other taxa. We further assessed whether common methods for sampling gastrointestinal (GI) microbes - cloacal swabs and faeces - provide accurate representations of these microbial communities. We found that different regions of the gut had unique microbial communities. The cloacal microbiome showed extreme specialization averaging 99% Proteobacteria (Phylum) and 83% Enterobacteriacaea (Family). Enterobacteriacaea decreased up the GI and reproductive tracts. Cloacal swabs recovered communities similar to that of lower intestine and cloacal tissues. In contrast, faecal samples had much higher diversity and a distinct composition (common Phyla: 62% Firmicutes, 18% Bacteroidetes, 10% Proteobacteria; common families: 39% Lachnospiraceae, 11% Ruminococcaceae, 11% Bacteroidaceae) relative to all gut regions. The common families in faecal samples made up <1% of cloacal tissue samples, increasing to 43% at the upper intestine. Similarly, the common families in gut tissue (Enterobacteriaceae and Helicobacteraceae) made up <1% of the faecal microbiome. Further, we found that cloacal swabs taken shortly after defaecation may be contaminated with faecal matter. Our results serve as a caution against using faeces as a proxy for GI microbes, and may help explain high between-sample variation seen in some studies using cloacal swabs.

Managing Gut Microbiota through In Ovo Nutrition Influences Early-Life Programming in Broiler Chickens

The chicken gut is the habitat to trillions of microorganisms that affect physiological functions and immune status through metabolic activities and host interaction. Gut microbiota research previously focused on inflammation; however, it is now clear that these microbial communities play an essential role in maintaining normal homeostatic conditions by regulating the immune system. In addition, the microbiota helps reduce and prevent pathogen colonization of the gut via the mechanism of competitive exclusion and the synthesis of bactericidal molecules. Under commercial conditions, newly hatched chicks have access to feed after 36-72 h of hatching due to the hatch window and routine hatchery practices. This delay adversely affects the potential inoculation of the healthy microbiota and impairs the development and maturation of muscle, the immune system, and the gastrointestinal tract (GIT). Modulating the gut microbiota has been proposed as a potential strategy for improving host health and productivity and avoiding undesirable effects on gut health and the immune system. Using early-life programming via in ovo stimulation with probiotics and prebiotics, it may be possible to avoid selected metabolic disorders, poor immunity, and pathogen resistance, which the broiler industry now faces due to commercial hatching and selection pressures imposed by an increasingly demanding market.

Association of female reproductive tract microbiota with egg production in layer chickens

BACKGROUND

The microbiota of the female reproductive tract is increasingly recognized as playing fundamental roles in animal reproduction. To explore the relative contribution of reproductive tract microbiomes to egg production in chickens, we investigated the microbiota in multiple reproductive and digestive tract sites from 128 female layer (egg-producing) chickens in comparable environments.

RESULTS

We identified substantial differences between the diversity, composition, and predicted function of site-associated microbiota. Differences in reproductive tract microbiota were more strongly associated with egg production than those in the digestive tract. We identified 4 reproductive tract microbial species, Bacteroides fragilis, Bacteroides salanitronis, Bacteroides barnesiae, and Clostridium leptum, that were related to immune function and potentially contribute to enhanced egg production.

CONCLUSIONS

These findings provide insights into the diverse microbiota characteristics of reproductive and digestive tracts and may help in designing strategies for controlling and manipulating chicken reproductive tract microbiota to improve egg production.

The digestive and reproductive tract microbiotas and their association with body weight in laying hens

Body weight at the onset of egg production is a major factor influencing hen productivity, as suitable body weight is crucial to laying performance in laying hens. To better understand the association between body weight and microbial community membership and structure in different sites of the digestive and reproductive tracts in chickens, we performed 16S rRNA sequencing surveys and focused on how the microbiota may interact to influence body weight. Our results demonstrated that the microbial community and structure of the digestive and reproductive tracts differed between low and high body weight groups. In particular, we found that the species Pseudomonas viridiflava was negatively associated with body weight in the 3 digestive tract sites, while Bacteroides salanitronis was negatively associated with body weight in the 3 reproductive tract sites; and further in-depth studies are needed to explore their function. These findings will help extend our understanding of the influence of the bird digestive and reproductive tract microbiotas on body weight trait and provide future directions regarding the control of body weight in the production of laying hens.