ZnO-NPs alleviate aflatoxin B1-induced hepatoxicity in ducklings by promoting hepatic metallothionein expression.

Aflatoxin B1 (AFB1) is a mycotoxin widely present in animal feed and human food, posing a serious threat to animal and human health. This study was aim to illustrate the mechanism of the protective role of MT against AFB1-induced hepatotoxicity, as well as to explore the feasibility of enhancing the tolerance of poultry to AFB1 by upregulating the expression of hepatic MT. After being exposed to AFB1 (50 ng/kg) primary duckling hepatocytes, the cell viability, the antioxidant index (SOD and GPx) and the mRNA levels of MT downstream genes (PTGR, p53, TrxR, AR and Bcl-2) significantly (p < 0.05) decreased, while the intracellular formation of (AFBO)-DNA adduct content, apoptosis, and MDA content significantly (p < 0.05) increased. Interestingly, overexpression of MT in primary duckling hepatocytes markedly (p < 0.05) reversed the detrimental impact of AFB1 and increased the expression of MT downstream genes. HepG2 cells were applied to study the mechanism how MT works to relieve the hepatic toxicity of AFB1. The ZnO-NPs (20 µg/mL) + AFB1 (20 µg/mL) group significantly (p < 0.05) increased the cell viability, the expression of NRF2, NQO1 and SOD, and expression of MT and MTF-1, as well as significantly (p < 0.05) decreased LDH, ROS and apoptotic rate, comparing with the AFB1 group. While joint treatment with AFB1 and ZnO-NPs, the hepatic toxicity exerted by AFB1 alone was reversed, along with the translocation of MTF-1 from the cytoplasm to the nucleus and upregulated its expression. Duckling trails were further carried out. A total number of 96 1-day-old healthy Cherry Valley commercial ducklings were randomly allocated according to a 2 by 2 factorial arrangement of treatments with the main factors including oral administration of AFB1 (0 vs. 40 µg/kg) and dietary supplementation of ZnO-NPs (0 vs. 60 mg/kg) for 7 days. It showed that AFB1 exposure caused body weight loss (p < 0.05), impaired liver structure and failure in hepatic function (activity of ALT, AST and concentration of TP and GLU) (p < 0.05), and decreases in antioxidant capacity(activity of SOD, CAT and concentration of GSH) (p < 0.05), along with the decrease in hepatic concentration of Zn, increase in expression of apoptosis-related genes and protein CAS3 and mRNA Bcl-2 expression (p < 0.05), and suppressed mRNA levels of antioxidant-related genes MT, SOD1, NRF2, and NQO1 (p < 0.05). In accordance with the cell test, dietary supplementation with ZnO-NPs mitigated the toxicity exerted by AFB1. In conclusion, ZnO-NPs has the protective effects against AFB1-induced hepatocyte injury by activating the expression of MTF-1 and the ectopic induction of MT expression, providing detailed information on the detoxification ability of MT on AFB1.

Effect of oral spray with Lactobacillus on growth performance, intestinal development and microflora population of ducklings.

OBJECTIVE: The aim of this study is to investigate the effect of oral spray with probiotics on the intestinal development and microflora colonization of hatched ducklings. METHODS: In Exp. 1, an one-way factorial design was used to study the antibacterial activity of the probiotics and metabolites on Escherichia coli (E. coli) without antimicrobial resistance. There were four experimental groups including saline as control and Lactobacillus, Bacillus subtilis, combined Lactobacillus and Bacillus subtilis groups. In Exp. 2, 64-day-old ducklings were allotted to 2 treatments with 4 replicated pens. Birds in the control group were fed a basal diet supplemented with Lactobacillus fermentation in the feed whereas birds in the oral spray group were fed the basal diet and administrated Lactobacillus fermentation by oral spray way during the first week. RESULTS: In Exp. 1, the antibacterial activities of probiotics and metabolites on E. coli were determined by the diameter of inhibition zone in order: Lactobacillus>combined Lactobacillusand Bacillus subtilis>Bacillus subtilis. Additionally, compared to E. coli without resistance, E. coli with resistance showed a smaller diameter of inhibition zones. In Exp. 2, compared to control feeding group, oral spray group increased (p<0.05) the final body weight at d 21 and average daily gain for d 1-21 and the absolute weight of the jejunum, ileum and total intestine tract as well as cecum Lactobacillus amount at d 21. CONCLUSION: Lactobacillus exhibited a lower antibacterial activity on E. coli with resistance than E. coli without resistance. Oral spray with Lactobacillus fermentation during the first week of could improve the intestinal development, morphological structure, and microbial balance to promote growth performance of ducklings from hatch to 21 d of age.

Immunization with a suicidal DNA vaccine expressing the E glycoprotein protects ducklings against duck Tembusu virus.

BACKGROUD: Duck Tembusu virus (DTMUV), a pathogenic flavivirus, emerged in China since 2010 and causing huge economic loss in the Chinese poultry industry. Although several vaccines have been reported to control DTMUV disease, few effective vaccines are available and new outbreaks were continuously reported. Thus, it is urgently to develop a new effective vaccine for prevention of this disease. METHODS: In this study, a suicidal DNA vaccine based on a Semliki Forest virus (SFV) replicon and DTMUV E glycoprotein gene was constructed and the efficacy of this new vaccine was assessed according to humoral and cell-mediated immune responses as well as protection against the DTMUV challenge in ducklings. RESULTS: Our results showed that the recombinant SFV replicon highly expressed E glycoprotein in DEF cells. After intramuscular injection of this new DNA vaccine in ducklings, robust humoral and cellular immune responses were observed in all immunized ducklings. Moreover, all ducklings were protected against challenge with the virulent DTMUV AH-F10 strain. CONCLUSIONS: In conclusion, we demonstrate that this suicidal DNA vaccine is a promising candidate facilitating the prevention of DTMUV infection.

Effects of feeding corn naturally contaminated with aflatoxin on growth performance, apparent ileal digestibility, serum hormones levels and gene expression of Na+, K+-ATPase in ducklings.

OBJECTIVE: A 14-d trial was conducted to determine the effects of feeding corn naturally contaminated with aflatoxin B1 (AFB1) on growth performance, apparent ileal digestibility, serum hormones levels and gene expression of Na+, K+-ATPase in ducklings. METHODS: A total of 704 ducklings were blocked on the basis of sex and body weight (BW), and then allocated randomly to one of the following two treatments: i) CON, basal diet and ii) AFB1, diets with 100% of normal corn replaced with AFB1 contaminated corn. There were 22 pens per treatment and 16 birds per pen. The concentration of AFB1 was 195.4 and 124.35 µg/kg in the contaminated corn and AFB1 diet, respectively. RESULTS: The AFB1 decreased average daily gain, average daily feed intake, d 7 BW, final BW in the whole trial, and feed conversion ratio (FCR) during d 8 to 14 and d 1 to 14 by 10% to 47% (p<0.05), while FCR during d 1 to 7 was increased (p<0.05). AFB1 did not affect mortality to 7 d of age, and then increased to 5.8% from 8 to 14 d of age (p<0.01). Apparent ileal gross energy digestibility was reduced by AFB1, whereas apparent ileal digestibility of dry matter, nitrogen, and amino acid was improved (p<0.01). Feeding AFB1 diets increased serum concentration of leptin and insulin-like growth factors-1 (IGF-1) (p<0.05), but had no effect on neuropeptide Y, ghrelin, cholecystokinin-8 or insulin (p>0.05). Dietary treatments did not influence relative expression of jejunal Na+, K+-ATPase gene (p>0.05). CONCLUSION: Taken together, feeding corn naturally contaminated with AFB1 reduced growth performance, improved apparent ileal digestibility, and affected serum leptin and IGF-1 in ducklings from d 1 to 14.

Experimental Infection of Common Eider Ducklings with Wellfleet Bay Virus, a Newly Characterized Orthomyxovirus.

Wellfleet Bay virus (WFBV), a novel orthomyxovirus in the genus Quaranjavirus, was first isolated in 2006 from carcasses of common eider (Somateria mollissima) during a mortality event in Wellfleet Bay (Barnstable County, Massachusetts, USA) and has since been repeatedly isolated during recurrent mortality events in this location. Hepatic, pancreatic, splenic, and intestinal necrosis was observed in dead eiders. We inoculated 6-week-old common eider ducklings with WFBV in an attempt to recreate the naturally occurring disease. Approximately 25% of inoculated eiders had onset of clinical disease and required euthanasia; an additional 18.75% were adversely affected based on net weight loss during the trial. Control ducklings did not become infected and did not have clinical disease. Infected ducklings with clinical disease had pathologic lesions consistent with those observed during natural mortality events. WFBV was reisolated from 37.5% of the inoculated ducklings. Ducklings surviving to 5 days postinoculation developed serum antibody titers to WFBV.

Evaluation of sulphur amino acid requirement of male Korean native ducklings from hatch to 21 day of age.

1. A dose-response experiment was conducted with male Korean native ducklings (KND) to evaluate the total sulphur amino acid (TSAA) requirement from hatch to 21 d of age. 2. A completely randomised design with 7 dietary TSAA concentrations (0.62%, 0.65%, 0.68%, 0.71%, 0.74%, 0.77% and 0.80%) were used with 6 replications per treatment. 3. Body weight (BW) and feed intake were measured weekly to calculate average daily gain (ADG), average daily feed intake (ADFI) and feed conversion ratio (FCR). One duckling per pen (n = 6) was killed by cervical dislocation to weigh empty body and drumsticks at the conclusion of experiment. 4. BW was improved significantly with increasing TSAA content, in a non-linear manner. A significant decrease of FCR was shown with increasing TSAA contents. TSAA requirement was determined by taking a mean value after fitting the data to both a linear-plateau and a quadratic-plateau model. Estimated TSAA requirements were 0.70%, 0.70%, 0.66% and 0.70% for the maximum BW, ADG and ADFI and for the minimum FCR, respectively. Increasing TSAA content improved quantity of full body weight (FBW), empty body weight (EBW) and drumstick weight (DSW), but there was no effect on proportion of DSW in relation to EBW and proportion of EBW to FBW. 5. In conclusion, the growth of male KND during 1 to 21 d of age was improved with increasing TSAA content, suggesting optimal TSAA requirements estimated by two analysis models.

Transcriptome analysis of the livers of ducklings hatched normally and with assistance.

OBJECTIVE: "Hatchability" is an important economic trait in domestic poultry. Studies on poultry hatchability focus mainly on the genetic background, egg quality, and incubation conditions, whereas the molecular mechanisms behind the phenomenon that some ducklings failed to break their eggshells are poorly understood. METHODS: In this study, the transcriptional differences between the livers of normally hatched and assisted ducklings were systematically analyzed. RESULTS: The results showed that the clean reads were de novo assembled into 161,804 and 159,083 unigenes (≥200-bp long) by using Trinity, with an average length of 1,206 bp and 882 bp, respectively. The defined criteria of the absolute value of log2 fold-change ≥1 and false discovery rate≤0.05 were differentially expressed and were significant. As a result, 1,629 unigenes were identified, the assisted ducklings showed 510 significantly upregulated and 1,119 significantly down-regulated unigenes. In general, the metabolic rate in the livers of the assisted ducklings was lower than that in the normal ducklings; however, compared to normal ducklings, glucose-6-phosphatase and ATP synthase subunit alpha 1 associated with energy metabolism were significantly upregulated in the assisted group. The genes involved in immune defense such as major histocompatibility complex (MHC) class I antigen alpha chain and MHC class II beta chain 1 were downregulated in the assisted ducklings. CONCLUSION: These data provide abundant sequence resources for studying the functional genome of the livers in ducks and other poultry. In addition, our study provided insight into the molecular mechanism by which the phenomenon of weak embryos is regulated.

Outbreaks of Human Salmonella Infections Associated with Live Poultry, United States, 1990-2014.

Backyard poultry flocks have increased in popularity concurrent with an increase in live poultry-associated salmonellosis (LPAS) outbreaks. Better understanding of practices that contribute to this emerging public health issue is needed. We reviewed outbreak reports to describe the epidemiology of LPAS outbreaks in the United States, examine changes in trends, and inform prevention campaigns. LPAS outbreaks were defined as ≥2 culture-confirmed human Salmonella infections linked to live poultry contact. Outbreak data were obtained through multiple databases and a literature review. During 1990-2014, a total of 53 LPAS outbreaks were documented, involving 2,630 illnesses, 387 hospitalizations, and 5 deaths. Median patient age was 9 years (range <1 to 92 years). Chick and duckling exposure were reported by 85% and 38% of case-patients, respectively. High-risk practices included keeping poultry inside households (46% of case-patients) and kissing birds (13%). Comprehensive One Health strategies are needed to prevent illnesses associated with live poultry.

The apparent metabolizable energy requirement of male Korean native ducklings from hatch to 21 days of age.

A study was conducted to determine the apparent metabolizable energy (AME) requirement of Korean native ducklings for hatch to 21 d of age. A total of 336 one-day-old male Korean native ducklings were used in a completely randomized design having 8 dietary treatments to provide a range of AME content from 2,600 to 3,300 kcal/kg (i.e., 100 kcal/kg disparity). Eight experimental diets containing varying levels of AME were formulated to meet the NRC (1994) nutrient specifications. Ducklings were randomly allocated to 48 pens (6 replicates per treatment and 7 ducklings per pen) and were offered their respective diets on an ad libitum basis for the period of study. Body weight and feed intake were measured weekly to calculate feed conversion ratio, energy intake, and protein intake. Two ducklings per pen (n = 6) were euthanized via cervical dislocation to weigh empty body and drumsticks at the conclusion of the experiment. Data were fitted to both linear-plateau and quadratic-plateau models for estimation of the AME requirements for Korean native ducklings for hatch to 21 d of age. The estimated AME requirements were 2,953, 3,007, and 2,950 kcal AME/kg diet for maximum daily gain, daily feed intake, and for minimum feed conversion ratio, respectively.

Natural Infection with H5N1 Highly Pathogenic Influenza (HPAI) Virus in 5- and 10-Day-Old Commercial Pekin Ducklings (Anas platyrhynchos domesticus).

Highly pathogenic avian influenza (HPAI) has resulted in catastrophic economic losses globally in poultry. This case report describes the diagnostic detection and pathology of HPAI H5N1 in 5-day-old commercial ducklings, which is an atypical age for detection of natural infection of HPAI in poultry. The pathology observed at 5 days of age was also compared to lesions observed in ducklings from the same flock evaluated at 10 days of age before depopulation. The California Animal Health and Food Safety (CAHFS) Laboratory, Tulare, received ten 5-day-old Pekin duckling (Anas platyrhynchos domesticus) carcasses for diagnostic evaluation due to mortality that started increasing at 3 days of age. The most common gross findings included bilateral pulmonary edema with congestion and enlarged, mottled livers and spleens. Microscopically, cerebral neuronophagia, pancreatic necrosis, and interstitial pneumonia with pulmonary edema were observed in the 5-day-old ducklings. Oropharyngeal and cloacal swabs were positive for avian influenza virus (AIV) by real-time reverse transcriptase PCR. The AIV was typed as HPAI, EA/AM 2.3.4.4b H5N1 goose/Guangdong clade lineage by the National Veterinary Services Laboratory. Ducks at the affected premises were depopulated 4 days after the 5-day-old ducklings were submitted to the CAHFS lab, at which time additional tissue samples were collected for comparison to 10-day-old ducklings on the same premises. Differences in microscopic lesions and AIV tissue distribution were observed between the 5-day and 10-day tissues collected. Notably, microscopic lesions were more severe in the brain and pancreas at 10 days of age. Findings in 10-day-old ducklings included cerebral lymphoplasmacytic perivascular cuffing, gliosis, neuronal degeneration, and pancreatic necrosis. AIV antigen distribution and intensity was greatest in the cerebral tissue of the brains at 10 days and in the lungs at 5 days of age. To the authors' knowledge, published studies are limited on AIV natural infection in domestic ducks less than 9 days of age.

Infección natural con el virus de la influenza altamente patógena (HPAI) H5N1 en patitos Pekín comerciales (Anas platyrhynchos domesticus) de 5 y 10 días de edad. La influenza aviar altamente patógena (HPAI) ha provocado pérdidas económicas catastróficas en todo el mundo entre las aves de corral. Este reporte de caso describe la detección diagnóstica y la patología de la infección por un virus de influenza aviar de alta patogenicidad H5N1 en patitos comerciales de 5 días de edad, que es una edad atípica para la detección de la infección natural del virus de la influenza aviar de alta patogenicidad en avicultura. La patología observada a los 5 días de edad también se comparó con las lesiones observadas en patitos de la misma parvada evaluados a los 10 días de edad, antes de la despoblación. El Laboratorio de Salud Animal y Seguridad Alimentaria de California (CAHFS), con sede Tulare, recibió 10 cadáveres de patito Pekín (Anas platyrhynchos domesticus) de 5 días de edad para su evaluación diagnóstica debido a que la mortalidad comenzó a aumentar a los 3 días de edad. Los hallazgos macroscópicos más comunes incluyeron edema pulmonar bilateral con congestión en hígado y bazos agrandados y moteados. Microscópicamente se observó neuronofagia cerebral, necrosis pancreática y neumonía intersticial con edema pulmonar en los patitos de 5 días de edad. Los hisopos orofaríngeos y cloacales fueron positivos para el virus de la influenza aviar (AIV) mediante transcripción reversa y PCR en tiempo real. El Laboratorio Nacional de Servicios Veterinarios clasificó al virus como de alta patogenicidad EA/AM 2.3.4.4b H5N1 clado de linaje de ganso/clado Guangdong. Los patos en las instalaciones afectadas fueron despoblados 4 días después de que los patitos de 5 días fueran enviados al laboratorio de CAHFS, momento en el cual se recolectaron muestras de tejido adicionales para compararlas con patitos de 10 días de las mismas instalaciones. Se observaron diferencias en las lesiones microscópicas y la distribución del tejido del AIV entre los tejidos recolectados de 5 y 10 días. En particular, las lesiones microscópicas fueron más severas en el cerebro y en el páncreas a los 10 días de edad. Los hallazgos en patitos de 10 días incluyeron infiltraciones linfoplasmocitarias perivasculares en el cerebro, gliosis, degeneración neuronal y necrosis pancreática. La distribución e intensidad del antígeno de influenza aviar fue mayor en el tejido cerebral de los cerebros a los 10 días y en los pulmones a los 5 días de edad. De acuerdo al conocimiento de los autores, los estudios publicados sobre la infección natural por el virus de la influenza aviar en patos domésticos de menos de 9 días de edad son limitados.

Effects of dietary inclusion of Moringa oleifera leaf meal on growth performance of Muscovy ducklings (Cairina moschata).

OBJECTIVE: The current experiment was performed to investigate the influence of different dietary levels of Moringa oleifera leaf meal (MOLM) on productive performance, nutrient digestibility, blood parameters, immune response, caecal microbiota, and carcass characteristics of Muscovy ducks (Cairina moschata) during 7 to 63 d of age. METHODS: A total of 240 unsexed 7-d-old ducklings were distributed into five (treatment) groups; each one contained six replicates with eight ducklings each. Birds of the first group were fed basal diet without MOLM and served as control, while the other four groups were fed basal diet with 0.25%, 0.50%, 1.0%, and 2.0% MOLM inclusion level, respectively. RESULTS: The obtained results revealed that including MOLM in the diets significantly improved body weight, body weight gain, feed conversion ratio and economic efficiency compared with the control group. Among the different MOLM inclusion treatments, increasing MOLM inclusion level decreased (p<0.05) such previous parameters. Decreasing MOLM inclusion levels in duckling diets increased (p>0.05) the digestibility of organic matter, crude protein, ether extract, and nitrogen free extract, however all MOLM treatments were significantly higher than the control group. Results also revealed that feeding ducks lower MOLM inclusion levels (0.25% or 0.50%) improved blood parameters (p<0.05) compared with the higher inclusion levels (1.0% or 2.0% MOLM) and the control group. Ducks fed different MOLM levels had significantly higher phagocyte index and activity, immunoglobulin G (IgG), IgM, total antioxidant capacity, glutathione peroxidase activity, and superoxide dismutase activity compared with control group. CONCLUSION: Despite the beneficial effects of all MOLM treatments on growth performance, nutrient digestibility, physiological status, and immune response of duckling, the increasing MOLM inclusion level in the diet had deleterious effects on such studied traits, consequently 0.25% was the best MOLM inclusion level in duckling diets.

The role of turmeric and black pepper oil nanoemulsion in attenuating cytokine storm triggered by duck hepatitis A virus type I (DHAV-I)-induced infection in ducklings.

The cytokine storm induced by duck hepatitis A virus type 1 (DHAV-1) infection significantly contributes to severe, rapid deaths and economic losses in the duck industry in Egypt. This study aimed to investigate the potential inhibitory effect of a nanoemulsion containing turmeric and black pepper oil on the immune response and pathogenesis of DHAV-1 in ducklings. A total of 105 ducklings from nonvaccinated breeders were divided into 5 experimental groups, each comprising 21 birds. The negative control group (G1) remained noninfected with DHAV-1 and nontreated with nanoemulsion, while the positive control group (G2) was infected with DHAV-1 but not treated with nanoemulsion. The other 2 groups (G3, the supplemented group which was noninfected with DHAV-1), and group 4 (the prophylactic group G4) which was infected with DHAV-1, both received nanoemulsion throughout the experiment. Group 5 (G5, the therapeutic group), on the other hand, which was infected with DHAV-1 received nanoemulsion only from the onset of clinical signs. At 5 days old, the ducklings in the positive control (G2), the prophylactic (G4), and the therapeutic group (G5) were infected with DHAV-1. All the ducklings in the infected groups exhibited depression, anorexia, and opisthotonos, and their livers displayed various degrees of ecchymotic hemorrhage, liver enlargement, and microscopic pathological lesions. Notably, the positive control group (G2) experienced the most severe and pronounced effects compared to the other infected groups treated with the nanoemulsion. Meanwhile, the viral RNA loads were lower in the liver tissues of the infected ducklings treated with the nanoemulsion (G4, and G5) compared to the positive control group G2. Additionally, the nanoemulsion effectively modulated proinflammatory cytokine expression, antioxidant enzymes, liver enzymes, and lipid profile of treated ducklings. In conclusion, the turmeric and black pepper oil nanoemulsion has the potential to be a therapeutic agent for regulating and modulating the immune response, decreasing DHAV-1-induced cytokine storms, and minimizing mortality and economic losses in the duck business. More research is needed to understand how turmeric and black pepper oil nanoemulsion alleviates DHVA-1-induced cytokine storms and lowers duckling mortality.

Effects of dietary nano-selenium supplementation on Riemerella anatipestifer vaccinated and challenged Pekin ducklings (Anas platyrhynchos).

Riemerella anatipestifer (RA) is a common disease causing economic losses to duck farms worldwide. Novel supplements are crucially needed to control this bacterium, enhance poultry performance, and produce synergistic effects with vaccines in stimulating the immune system. This study investigated the effect of nano-selenium (Nano-Se) on the vaccinated (VAC) and challenged (Ch) Pekin ducklings (Anas platyrhynchos) with RA. Five experimental groups (G1-G5) were included in this study: G1 was the control group, G2 was the RA-challenged group, G3 was the Nano-Se+Ch group, G4 was the VAC+Ch group, and G5 was the Nano-Se+VAC+Ch group. The Nano-Se (0.3 mg/kg diet) was supplemented for 5 weeks post-vaccination (PV). The ducklings were vaccinated subcutaneously with the RA vaccine at 7 days of age and challenged with RA at the 3rd week PV. Blood, pharyngeal swabs and tissue samples were collected at the 3rd week PV and at different times post-challenge (PC). The growth performance (weight gain and feed conversion ratio), clinical signs, gross lesions, mortality, bacterial shedding, haematological, immunological, and biochemical parameters, cytokines production, and histopathological lesion scores showed significant differences (P < 0.05) between the challenged (G2) group and the supplemented (G3 & G5) groups. G5 showed the highest (P < 0.05) growth performance, phagocytic activity, IgM and IgG, splenic interleukin-2 (IL-2), IL-10, and interferon-gamma (IFN-γ) gene expressions, and the lowest mortality, bacterial shedding, hepatic and renal damage, heterophil/lymphocyte ratio and lesion scores compared to the other groups. In conclusion, the supplementation of nano-selenium for five weeks in the diet can improve the growth performance, immune status, and cytokines production in ducklings vaccinated and challenged with RA.

Evidence of vertical transmission of fowl adenovirus 8b in ducks.

Fowl adenovirus mainly causes hydropericardium hepatitis syndrome (HHS), inclusion body hepatitis (IBH) and gizzard erosion (GE), etc. In 2015, the first outbreak of HHS was reported in broiler chickens in central China, followed by an outbreak in waterfowl. The first outbreak of HHS in broiler flocks in central China in 2015, followed by outbreaks in waterfowl, has severely restricted the healthy development of the poultry industry. During the investigation, fowl adenovirus was detected in ducklings from a total of seven hatcheries in Shandong, Inner Mongolia and Jiangsu provinces. In addition, the DNA of fowl adenovirus was detected in breeding ducks and their progeny. To test the hypothesis that FAdV can be transmitted vertically, sixty 250-day-old Cherry Valley breeder ducks were divided equally into three groups for experimental infection. FAdV-8b SDLY isolate (duck/Shandong/SDLY/2021, SDLY) preserved in our laboratory was injected intramuscularly into group A and inoculated orally into group B. FAdV-8b DNA was detected in the yolk membranes, embryos and allantoic fluid of duck embryos in the FAdV-infected group after inoculation. In addition, the FAdV-8b hexon gene isolated from yolk membranes, embryos, allantoic fluid and duck eggs was close to 100% nucleotide homology to the FAdV-8b hexon gene isolated from laying duck ovaries, indicating that fowl adenovirus can be transmitted vertically in ducks. These findings provide evidence for the possible vertical transmission of fowl adenovirus from breeder ducks to ducklings.

The impact of Bacillus subtilis DSM32315 and L-Threonine supplementation on the amino acid composition of eggs and early post-hatch performance of ducklings.

Poultry requires Threonine, an essential amino acid, and its metabolites for proper metabolic function. Threonine is crucial in the biosynthesis of mucin, which is essential for intestinal health and nutrient absorption. Bacillus subtilis (B. subtilis) is a potential substitute for antibiotic growth promoters in the poultry industry. The current study was designed to evaluate the simultaneous effect of L-Threonine (Thr) and B. subtilis DSM32315 supplementation on laying duck breeders in order to maximize performance. A total number of 648 female 23-week-old Longyan duck breeders were assigned to a 3 × 2 factorial design with six replicates of 18 birds per replicate. L-Thr was added to the control diet at concentrations of 0, 0.7, and 1.4 g/kg, equating to 3.9, 4.6, and 5.3 g Thr/kg, with or without B. subtilis strain DSM 32315 (0.0 and 0.5 g/kg). Increasing Thr concentrations improved egg production and ducklings' hatchling weight (p < 0.05). In addition, L-Thr supplementation resulted in a tendency for decreased feed conversion ratio without affecting egg quality. There was no significant effect (p > 0.05) of the dietary Thr levels on egg yolk and albumen amino acid concentrations. In contrast, the addition of B. subtilis decreased the concentrations of amino acids, excluding proline, in the egg white (albumen) and the egg yolk (p < 0.05). Furthermore, the supplementation of B. subtilis decreased (p < 0 0.001) the hatching weight of ducklings. The addition of B. subtilis without L-Thr decreased (p < 0.05) the hatchability of fertile eggs and the hatching weight of ducklings compared to those of ducks fed dietary L-Thr along with B. subtilis (p < 0.001). The combining L-Thr at 0.7 g/kg with B. subtilis DSM 32315 at 0.5 g/kg could increase eggshell quality, hatchability, and hatching weight. The current study revealed that the combination supplemented of L-Thr and B. subtilis DSM 32315 is recommended due to its positive effects on the eggshell percentage, hatchability and the body weights of newly hatched ducklings when dietary Thr was added at a rate of 0.7 g/kg and B. subtilis DSM 32315 at 0.5 g/kg. In addition, adding L-Thr separately at 0.7 g/kg could improve the egg production of duck breeders. Further studies are required to find the proper dosages of B. subtilis DSM 32315 with co-dietary inclusion of limiting amino acids in the diets of duck breeders. The findings of these trials will support feed additive interventions to transition into antibiotic-free diets.

Immunopotentiators improve the antioxidant defense, apoptosis, and immune response in Shaoxing ducklings.

The abuse of antibiotics for agricultural purposes has been under scrutiny. Therefore, there is an urgent need to find antibiotic substitutes in animal production. The effects of chlorogenic acid, ß-D-Glucan, astragalus flavone, CpG-DNA, and chicken IgG on spleen antioxidant capacity, apoptosis, and the immune response in Shaoxing ducklings were investigated in this study. The ducklings treated with ß-D-Glucan, astragalus flavone, CpG-DNA, and chicken IgG showed significant reduction in catalase and superoxide dismutase activities. The five immunopotentiators facilitated caspase 3 expression and reduced Bcl2 expression in the spleen. Compared to the control group, the protein level of COX2 was significantly upregulated in the chlorogenic acid, CpG-DNA, and chicken IgG groups. The protein level of iNOS expression was significantly improved in all immunopotentiator groups, except for the astragalus flavone group. The five immunopotentiators induced IL-1ß, IFN-α, IFN-ß, TNF-α, RIG-I, TLR3, and TLR7 gene expression. In summary, chlorogenic acid, ß-D-Glucan, astragalus flavone, CpG-DNA, and chicken IgG, as immunopotentiators, improved the innate immune response in the ducklings, which not only provides a new avenue for the development of efficient approaches to prevent pathogen infections, but also offers an alternative to antibiotics in animal production.

Curcumin activates the Nrf2 Pathway to alleviate AFB1-induced immunosuppression in the spleen of ducklings.

Ducklings is one of the most susceptible poultry to Aflatoxin B1 (AFB1) which widely existed in duckling products will also in turn affect human health. Curcumin (CUR) has significant effects on immune regulation and anti-oxidation. But whether CUR alleviates toxic effects on duckling spleen induced by AFB1 remains largely unknown. In this study we treated duckings with AFB1 and CUR for 21 days before harvesting serum and spleen tissue for analyses. The results showed that AFB1 damaged the spleen tissue of ducklings by activating the NF-κB signaling pathway. And the addition of CUR not only promoted the growth of ducklings, but also enhanced the immune function of the spleen and reduced the damage of AFB1 to the spleen tissue. At the same time, CUR activated the Nrf2 signaling pathway, upregulated the expression of related antioxidant enzymes, inhibited the NF-kB signaling pathway, and ultimately reducing the inflammation of the duckling spleen induced by AFB1. It has been suggested from these results that Nrf2 pathway might be a potential therapeutic target for CUR to treat AFB1-induced immunosuppression in ducklings.

Effect of TMUV on immune organs of TMUV infected ducklings.

Tembusu Virus (TMUV), a pathogenic member of Flavivirus family, acts as the causative agent of egg-laying and has severely threatened the duck industry over the past few years. Thus far, the pathogenicity of such virus has been extensively studied, whereas TMUV on immune system has been less comprehensively assessed, especially on ducklings that exhibit more susceptible to TMUV attack. Accordingly, in the present study, 5-day-old ducklings were infected with TMUV-TC2B (104 TCID50) via intravenous injection, and mock ones were inoculated with phosphate-buffered saline (PBS) in identical manner as control. At 1 day-post inoculation (dpi), the innate immunity was strongly activated, and reacted rapidly to TMUV invasion, which was reflected as the significantly up-regulated IFN-stimulated genes (ISGs), especially in immune organs (e.g., thymus, bursa of Fabricius (BF) and spleen). Subsequently, under the continuous monitoring, the levels of IgA, IgM and IgG acting as the representative immunoglobulins (Igs) were constantly higher than those of mock ducklings, demonstrating that humoral immunity also played a major role in anti-virus infection. Despite the immune system activated positively, TMUV still caused systemic infection, and in particular, the immune organs were subject to severe damage in the early infection. With our constant observation, the injury of spleen and BF turned out to be getting more serious, and at 6 dpi, TMUV antigen was widely detected in both of two immune organs by immunohistochemistry (IHC) and main histopathological lesion presented as lymphocytopenia. Moreover, the elevated apoptosis rate of splenic lymphocytes and the alteration of immune organ index also revealed the damage of lymphoid organs and similarly, it is worth noting that severe damages were detected in thymus of TMUV-infected ducklings as well. In brief, the present study systematically described the dynamic damage of immune system after being attacked by TMUV and presented insights into the research of pathogenicity.

Comparative consequences of two sources of aflatoxins in ducklings experimental aflatoxicosis.

The purpose of this study was to investigate the effect of two aflatoxins (AFs) sources for experimental induction of aflatoxicosis in ducklings. Dietary supplementation of aflatoxin-contaminated grounded rice grains previously was cultured by Aspergillus parasiticus and dietary supplementation of aflatoxin methanolic extract of contaminated rice grains. A total number of 18 four-day-old ducklings were treated with varying sources of AFs. Treatments included: A: Control (basal diet without AFs), B: Contaminated feed with 0.20 mg kg-1 AFs (ground rice grains), C: Contaminated feed with 0.20 mg kg-1 AFs (methanol extract of contaminated rice grains). Results showed a significant decrease in serum levels of total protein, albumin, glucose, triglyceride, cholesterol, HDL, LDL and creatinine. The serum's hepatic enzymes levels were not affected in AFs-treated groups but lactate dehydrogenase (LDH) concentration increased by the two AFs sources. The relative weight of the liver and spleen was significantly increased in AFs-fed groups. Histopathological liver examination showed the vacuolar degeneration with small and large lipid droplets in hepatocytes in the AFs- contaminated groups. Dietary AFs resulted in a significant decrease of villus height, villus width and villus surface area of the small intestine compared to the control group. In conclusion, the results showed that the induction of experimental aflatoxicosis via two investigated AFs sources had slight differences concerning the studied parameters. It seems the group consumed ground rice grains indicated slightly fewer aflatoxicosis symptoms than the methanolic extract.

Molecular Characterization, Virulence and Antimicrobial Susceptibility Testing of Riemerella anatipestifer Isolated from Ducklings.

This pilot study aimed to characterize Riemerella anatipestifer from ducklings, testing their susceptibility to antimicrobial agents and to detect their virulence markers. Seven R. anatipestifer isolates with 11.67% infection rate were identified out of sixty freshly dead ducklings and confirmed by PCR assay targeting gyrB gene. The gyrB gene sequences of R. anatipestifer isolates were 100% identical to each other and also showed 100% sequence similarity to the published gyrB genes. Four virulence genes namely ompA, prtC, hagA, and sspA were identified in all isolates except sspA was detected in 5 isolates. The antibiogram revealed higher sensitive to imipenem, amikacin, and rifampin, while, a remarkably high resistance was displayed against ampicillin, penicillin, cefipime, trimethoprim/sulfamethoxazole, gentamicin, ceftazidime, streptomycin and cefoperazone. Proper and rapid identification of R. anatipestifer with detection of their antimicrobial susceptibility and its virulence potential is essential for understanding the epidemiology of R. anatipestifer and to apply the effective control strategies.