Success rates of inoculation of the various compartments of embryonated chicken eggs at different incubation days

Longitudinal volumetric analysis of in ovo compartments in chicken eggs using ultra-high-field magnetic resonance imaging

Introduction

The chicken egg, with its in ovo compartments, is a widely used and popular animal model in experimental studies. This study aimed to quantify the volumes of the yolk/yolk sac, amniotic fluid, and chicken embryo in ovo using non-invasive ultra-high-field magnetic resonance imaging (UHF-MRI).

Materials and methods

In total, 64 chicken eggs were examined using a 7 T UHF-MRI scanner, acquiring T2-weighted anatomical images of the entire egg from developmental day 1 to 16 (D1-D16). Four eggs were scanned each developmental day, and the volumes of the yolk/yolk sac, amniotic fluid, and embryo were quantitatively assessed.

Results

UHF-MRI facilitated the in ovo quantitative assessment of the yolk/yolk sac starting from D1 and the embryo from D5 onward. The yolk/yolk sac volume increased from D1 to D6 before progressively decreasing until D14. The amniotic cavity could be detected on D6, with its fluid volume increasing steadily until D14. The embryo's volume increased consistently throughout the developmental period, reaching its peak at D16.

Discussion

UHF-MRI allows in vivo assessment of embryonic development, providing non-invasive, longitudinal insights into the volumes of the yolk/yolk sac, amniotic fluid, and chicken embryo. The investigation method described in this study may provide a standardized model for biomedical research in the developing chicken embryo, supporting various experimental applications.

Quercetin attenuates lipopolysaccharide-induced hepatic inflammation by modulating autophagy and necroptosis

Lipopolysaccharide (LPS) from Gram-negative bacteria initially induces liver inflammation with proinflammatory cytokines expressions. However, the underlying hepatoprotective mechanism of quercetin on LPS-induced hepatic inflammation remains unclear. Specific pathogen-free chicken embryos (n = 120) were allocated control vehicle, PBS with or without ethanol vehicle, LPS (125 ng/egg) with or without quercetin treatment (10, 20, or 40 nmol/egg, respectively), quercetin groups (10, 20, or 40 nmol/egg). Fifteen-day-old embryonated eggs were inoculated abovementioned solutions via the allantoic cavity. At embryonic d 19, the livers of the embryos were collected for histopathological examination, RNA extraction, real-time polymerase chain reaction, and immunohistochemistry investigation. We found that the liver presented inflammatory response (heterophils infiltration) after LPS induction. The LPS-induced mRNA expressions of inflammation-related factors (TLR4, TNFα, IL-1β, IL-10, IL-6, MYD88, NF-κB1, p38, and MMP3) were upregulated after LPS induction when compared with the PBS group, while quercetin could downregulate these expressions as compared with the LPS group. Quercetin significantly decreased the immunopositivity to TLR4 and MMP3 in the treatment group when compared with the LPS group. Quercetin could significantly downregulate the mRNA expressions of autophagy-related genes (ATG5, ATG7, Beclin-1, LC3A, and LC3B) and necroptosis-related genes (Fas, Bcl-2, Drp1, and RIPK1) after LPS induction. Quercetin significantly decreased the immunopositivity to LC3 in the treatment group when compared with the LPS group; meanwhile, quercetin significantly decreased the protein expressions of LC3-I, LC3-II, and the rate of LC3-II/LC3-I. In conclusions, quercetin can alleviate hepatic inflammation induced by LPS through modulating autophagy and necroptosis.

Effects of in ovo vaccination time on broiler performance parameters under field conditions

Hatchery performance is often evaluated based on descriptors such as hatchability, 7-d mortality, and cost. In addition to these descriptors, it is useful to include in this analysis aspects of chick quality through post-hatch performance. Realizing the bird's complete genetic potential necessitates meeting various criteria, with effective support for the chick's immune system being among the pivotal factors. To be effective, in ovo vaccination systems must deliver the vaccines to specific sites in the egg, a circumstance that directly depends on when the injection is made. We examined production data to evaluate the impact of in ovo vaccination time on performance parameters of male Ross308AP chicks. A comprehensive survey was conducted examining records from 3,722 broiler flocks produced and raised by the same company under standard nutrition and management conditions. The selected data specifically pertained to flocks that underwent slaughter between 41 and 45 d. In our analysis, 4 different linear models were built, one for each response variable: mean weight (MW), body weight gain (BWG), corrected feeding conversion rate (cFCR), and total mortality (TM). The linear models used in the analyses included as main predictor the timing of in ovo vaccination (440, 444, 448, 452, 456, 458, and 460 h of incubation), and as additional predictors: age of the breeding flock (26-35, 36-55 and 56-66 wks old), slaughter age, identity of the hatchery, and the season at which the data was collected. Our results showed that the timing of in ovo vaccination significantly affected BWG and cFCR, with procedures performed at 460 h of incubation showing the best outcomes. Breeding flock age affected all response variables, with older breeding flocks delivering increased MW, BWG and TM, and middle-aged flocks increased cFCR. Increasing slaughter age reduced BWG while MW, cFCR and TM were all increased. These data emphasize the benefits of performing in ovo vaccination as close as possible to 460 h of incubation to extract the best BWG and cFCR from Ross308AP male broiler.

Enterococcus cecorum lesion strains are less sensitive to the hostile environment of albumen and more resistant to lysozyme compared to cloaca strains

RESEARCH HIGHLIGHTS

Egg albumen inhibits Enterococcus cecorum cloaca strains more than lesion strains.Enterococcus cecorum lesion strains are resistant to high concentrations of lysozyme.Lysozyme resistance could enhance survival in albumen and body fluids.

Quercetin Alleviates Inflammation and Energy Deficiency Induced by Lipopolysaccharide in Chicken Embryos

Energy deficiency causes multiple organ dysfunctions after LPS induction. Quercetin is a phenolic compound found in herbal medicines. However, the effects of quercetin in alleviating LPS-induced energy deficiency remain unclear. In the present study, an in vivo LPS-induced inflammation model was established in chicken embryos. Specific pathogen-free chicken embryos (n = 120) were allocated to control, PBS with or without ethanol, quercetin (10, 20, or 40 nmol, respectively), and LPS (125 ng/egg) with or without quercetin groups. Fifteen day old embryonated eggs were injected with the abovementioned solutions via the allantoic cavity. On embryonic day 19, the tissues of the embryos were collected for histopathological examination using frozen oil red O staining, RNA extraction, real-time quantitative polymerase chain reaction, and immunohistochemical investigations. The glycogen and lipid contents in the liver increased after LPS stimulation as compared with the PBS group, whereas quercetin decreased the accumulation as compared with the LPS group. The mRNA expressions of AMPKα1 and AMPKα2 in the duodena, ceca, and livers were upregulated after LPS induction as compared with the PBS group, while quercetin could downregulate these expressions as compared with the LPS group. The immunopositivity of AMPKα2 in the villus, crypt, lamina propria, tunica muscularis, and myenteric plexus in the duodena and in the cytoplasms of hepatocytes significantly increased after LPS induction when compared with the PBS group (p < 0.01), whereas the immunopositivity to AMPKα2 in the quercetin treatment group significantly decreased when compared with the LPS group (p < 0.01 or p < 0.05). The LPS-induced high expressions of transcription factor PPARα and glucose transporter (SGLT1) were blocked by quercetin in the duodena, ceca, and livers. Quercetin treatment improved the LPS-induced decrease in APOA4 in the duodena, ceca, and livers. The mRNA expression of PEPT1 in the duodena and ceca increased after LPS challenge, whereas quercetin could downregulate PEPT1 gene expression. These data demonstrate that quercetin improved the energy deficiency induced by LPS in chicken embryos. The LPS-induced inflammation model was established to avoid the effect of LPS exposure from the environment and intestinal flora. The results form the basis the administration of quercetin pretreatment (in ovo infection) to improve the energy state of chicken embryos and improve the inflammation response.

Quercetin Ameliorates Lipopolysaccharide-Induced Duodenal Inflammation through Modulating Autophagy, Programmed Cell Death and Intestinal Mucosal Barrier Function in Chicken Embryos

Diarrhea has been a global health problem for centuries, and the treatment has become increasingly difficult duo to the antibiotics overuse and resistance. Quercetin is a common flavonoid of extracts of vegetables, fruits, and traditional Chinese herbs, however, the mechanism of quercetin alleviating LPS-induced duodenal inflammation remains elusive. Specific pathogen-free chicken embryos (n = 120) were allocated to groups including control, PBS with or without alcohol, LPS (125 ng/egg) with or without quercetin (10, 20, or 40 nmol/egg, respectively), and quercetin groups (10, 20, or 40 nmol/egg). Fifteen day-old embryonated eggs were inoculated with abovementioned solutions via the allantoic cavity. At embryonic day 19, the duodena of the embryos were collected for histopathological examination, RNA extraction and real-time polymerase chain reaction, immunohistochemical investigations, and Western blotting. The results demonstrated quercetin enhanced the inflammatory cell infiltration in the Peyer's patch of the intestinal mucosa after LPS induction. The LPS-induced expressions of these inflammation-related factors (TLR4, IL-1β, MMP3, MMP9, NFKB1, IFNγ, IL-8, IL-6) were completely blocked by quercetin. Quercetin also decreased the protein expression of TLR4, IL-1β, MMP3, and MMP9 after LPS induction. Quercetin could down-regulate autophagy gene expression (ATG5, LC3-1, LC3-2, and LKB1), and decreased the protein expression of ATG5, and LC3-1/LC3-2 after LPS induction. Quercetin treatment prevented LPS-induced increases of the gene expressions of programmed cell death factors (TNFα, Fas, CASP1, CASP3, CASP12, Drp1, and RIPK1); meanwhile, quercetin decreased the protein expression of CASP1 and CASP3 after LPS challenge. LPS reduced the gene expression of mucin 2, but upregulated the mRNA and protein expression of claudin 1, occludin, and ZO-1, and this was balanced by quercetin. This evidence suggests that quercetin can alleviate duodenal inflammation induced by LPS through modulating autophagy, programmed cell death, intestinal barrier function.

Assessment of the best inoculation route for virulotyping Enterococcus cecorum strains in a chicken embryo lethality assay

AbstractThe study aim was to determine the best inoculation route for virulotyping Enterococcus cecorum in a chicken embryo lethality assay (ELA). Twenty-eight genetically different strains were used. Fourteen strains were isolated from cloaca swabs of broiler reproduction chickens (cloaca strains) and fourteen strains from broilers with E. cecorum lesions (lesion strains). In all ELAs, 12 days incubated embryonated broiler eggs were inoculated with approximately 100 colony forming units of E. cecorum/egg. Twenty embryos per inoculation route and strain were used in each of three experiments. In Experiment 1, four cloaca and four lesion strains were inoculated via various routes, i.e. albumen, amniotic cavity, allantoic cavity, chorioallantoic membrane, intravenous or air chamber. The albumen inoculation route showed low mortality with cloaca strains, high mortality with lesion strains and the largest difference in mortality between these groups of strains (≥60%). This route was therefore used in subsequent experiments. In Experiment 2, the same strains were used to test reproducibility, which proved to be generally good. All 28 strains were thereafter used in Experiment 3. In the three experiments, mortality by cloaca and lesion strains ranged from 0 to 25% and from 15 to 100%, respectively. Recovery rates, assessed in all experiments after albumen inoculation, were significantly lower from eggs inoculated with cloaca strains, compared to lesion strains inoculated eggs (P <0.05). However, the bacterial load of eggs with positive recovery was similar in both groups. In conclusion: the albumen inoculation route appeared to be the best to virulotype E. cecorum strains.

In vivo typing of Escherichia coli obtained from laying chickens with the E. coli peritonitis syndrome

RESEARCH HIGHLIGHTS

Even at high doses not any E. coli strain can induce EPSSubstantial differences in virulence exist within very virulent E. coli strainsThe embryo lethality test is a useful alternative for biotyping E. coli in laying hensBroiler colibacillosis may represent a source of EPS strains for layers and vice versa.