农林科学最新文献

Myiasis due to parasitic fly larvae (maggots) can have major consequences for animal health and welfare. The European hedgehog Erinaceus europaeus is frequently presented in rehabilitation centres and veterinary practices due to health problems, including myiasis. In the present study, 557 hedgehogs presented at wildlife rehabilitation centres in Northern Germany during 2018-2021 were examined for the presence of dipteran eggs and larvae. Overall, 15.6% of animals carried fly eggs and/or larvae. Four different dipteran species were identified by PCR and sequencing of the internal transcribed spacer 2 (ITS-2) region. Lucilia sericata was detected on 25.3% [22/87] of affected hedgehogs, followed by Calliphora vicina (12.6% [11/87]), Lucilia ampullacea (11.5% [10/87]) and Lucilia caesar (9.2% [8/87]). Myiasis prevalence was significantly higher during the summer compared to spring and autumn. Fly eggs were found all over the body, while larvae were detected most frequently in the body's natural orifices and in wounds. Regarding rehabilitation success, myiasis occurred significantly more frequently in animals that died or were euthanized compared to those released back into the wild. Although the high death rate probably arose in combination with underlying disease, this illustrates that myiasis represents a serious health issue that should be diagnosed and treated immediately.

Coccidiosis is a global disease caused by protozoans, typically including Eimeria spp., which pose a significant threat to the normal growth and development of young animals. Coccidiosis affects mainly the gut, where parasite proliferation occurs. The intestinal barrier, which consists of chemical, mechanical, biological, and immune defences, plays a crucial role in protecting the host against pathogens, xenobiotics, and toxins present in the gastrointestinal tract. When animals ingest sporulated Eimeria spp. oocysts, these parasites primarily reproduce in the intestinal tract, causing damage to the structure and function of the intestine. This disruption of intestinal homeostasis adversely affects animal health. Numerous studies have also revealed that Eimeria-infected animals experience slower bone growth rates, inferior meat quality, reduced egg production and quality, as well as impaired growth and development. Therefore, the purpose of this review is to examine the underlying mechanisms through which Eimeria spp. regulate intestinal damage and disturb the balance of the internal environment. Specifically, this review will focus on their effects on the structural basis of the host intestine's chemical, mechanical, biological and immune barriers. This understanding is crucial for the development of effective drugs to prevent the invasion of Eimeria spp. into the intestine, which is of paramount importance for maintaining host health.

The Duck Tembusu virus (DTMUV) was first reported in China in 2010 and has since caused substantial economic losses in the poultry breeding industry. In the autumn of 2022, an outbreak of an infectious disease resembling DTMUV was reported in Guangdong Province, China, which caused significantly high mortality in goose embryos, and decreased egg production. This study identified one strain of the new subgenotype 3 of DTMUV, designated as DTMUV GDZQ2022, responsible for these effects. Comprehensive genomic sequencing of this strain was conducted to analyse its genetic variations. Additionally, the isolated and purified virus was inoculated into goose embryos and goslings to assess its pathogenicity. The GDZQ2022 genome displayed over 88% nucleotide homology with other DTMUV strains from China and Southeast Asia. Phylogenetic analysis of the E gene classified GDZQ2022 within the subgenotype 3 of DTMUV. Pathogenicity experiments on goose embryos and goslings showed that the GDZQ2022 strain induced typical clinical signs of DTMUV, particularly severe neurological manifestations. Although GDZQ2022 exhibited high virulence in goose embryos, its virulence in goslings was minimal, resulting in a low mortality rate. Pathological examinations detected significant histological lesions in the brains, livers, and spleens of the infected goslings. In conclusion, this study presents the first evidence of a novel DTMUV strain proliferating among young geese in China, underscoring the genetic diversity of DTMUV and contributing to our understanding of the pathogenicity of the subgenotype 3 Tembusu virus in goose embryos and goslings.RESEARCH HIGHLIGHTSPathogenicity of subgenotype 3 duck Tembusu virus in goose embryos and goslings was shown for the first time.DTMUV GDZQ2022 strain is highly pathogenic in goose embryos.The virulence of the DTMUV GDZQ2022 strain in goslings is relatively mild.Infected goslings exhibit typical clinical manifestations, with a low mortality rate.

We characterized 15 H5N1 HPAI viruses from different small- and medium-scale poultry flocks across Bangladesh during 2018-2021 based on their complete genome sequences. The antigenic relatedness of H5N1 HPAI viruses from different timepoints was analysed. During 2020-2021, 42.11% of the flocks tested positive for at least one of the respiratory infections, with 15.79% showing influenza A virus, of which 8.77% tested positive for HPAIV H5N1. Co-infections with two to four pathogens were detected in 15.8% of flocks. Phylogeny and gene constellation analyses based on complete genome sequences of 15 HPAI viruses revealed the continuing circulation of H5 clade 2.3.2.1a genotype G2 viruses. In the HA protein of the study isolates, functionally meaningful mutations caused the loss of an N-linked glycosylation site (T156A), a modified antigenic site A (S141P), and a mutation in the receptor binding pocket (E193R/K). Consequently, antigenic analysis revealed a significant loss of cross-reactivity between viruses from different host species and periods. Most viruses displayed oseltamivir resistance markers at positions V96, I97, S227, and N275 (N1 numbering) of the NA protein. In addition, for the PB2, M1, and NS1 proteins, significant mutations were noticed that have been associated with polymerase activity and increased virulence for mammals in all study isolates. These results highlight the need for intensified genomic surveillance of HPAI circulating in poultry in Bangladesh and for establishing appropriate control measures to decrease the circulation of these viruses in poultry in the country.

Mycoplasma gallisepticum (Mg) and Mycoplasma synoviae (Ms) are regarded as the most important avian mycoplasma species for today's chicken and turkey farming industry from clinical and economical perspectives. Control strategies for Mg and Ms have become more efficient due to investments in mycoplasma research over the last 70 years. These investments have contributed to the further implementation of serological and molecular testing, the development of vaccines, and the improvement of antimicrobial treatment strategies. However, the increasing spotlight on welfare, the pressure on prudent use of antimicrobials, and the expected global increase in poultry production, are going to have an impact on the future control of avian mycoplasmas in commercial poultry. In this paper a group of avian mycoplasma experts discuss the future challenges in mycoplasma control considering the background of these expected changes and the relevance for future avian mycoplasma research.

Two vaccination-challenge trials were performed using a commercial infectious bronchitis virus (IBV) BR1 vaccine, given alone or combined with a commercial IBV Mass vaccine against challenges with IBV M41, 793B, D388 (QX), Q1, Brasil-1 or Variant 2 challenge viruses, which includes the IB viruses that are dominant in South America. The efficacy of the vaccines against the challenge viruses was investigated by determination of the ciliary activity of the tracheal epithelium after challenge. The level of protection induced by the IBV BR1 vaccine alone against the six IBV challenge strains, of which five were of heterologous genotypes, varied from 50% to 100% with an average of 80%. The level of protection induced by the combination of the IBV BR1 and IBV Mass vaccines against the six IBV challenge strains, of which four were of heterologous genotypes, varied from 80% to 100% with an average of 92%. Vaccination with IBV BR1 alone provided a high level of protection against most tested challenge viruses, though the combination of IBV BR1 and IBV Mass was more consistent, showing less variation and compliance with the criterium mentioned in the European Pharmacopoeia 10th edition (at least 80% protection) for all tested challenge viruses. These trials show that vaccination with a combination of IBV BR1 and IBV Mass vaccines provides high levels of protection against the circulating IBV strains in South America.

Inclusion body hepatitis (IBH) is an economically important viral disease primarily affecting the poultry industry. In this study, we isolated a strain of FAdV-8b (strain SDYT) from naturally infected ducks and the hexon and fiber gene sequences were analysed by polymerase chain reaction (PCR) amplification. In order to study the pathogenicity of FAdV-8b in Cherry Valley ducks, we inoculated 10- and 20-day-old ducks with 0.3 ml of FAdV-4 virus (TCID₅₀ of 10^5.5/0.1 ml) either orally or intramuscularly. Clinical signs, gross lesions and histopathological changes, cytokines, viral load and antibody levels were observed and recorded within 15 days after infection. Pathomorphological investigations revealed that ducks in the experimental group exhibited hepatitis. Histopathology showed multiple organ damage, including serious liver and kidney lesions. Furthermore, elevated levels of inflammatory cytokines and antibodies were noticed, due to the infection and innate immune response. At a later stage of infection, immunosuppression occurred, resulting in decreased levels of cytokines. Determination of viral load showed that the virus was present in several organs, with the highest viral DNA load found in the liver, followed by the kidney. Compared to birds infected orally, the intramuscular group exhibited the highest viral load. In summary, this study increases our understanding of the pathogenicity of FAdV-8b in ducks and establishes a model that will inform antiviral drug testing and vaccine evaluation for IBH, thereby preventing and reducing the spread of IBH in the poultry industry.RESEARCH HIGHLIGHTSA strain (SDYT) of fowl adenovirus 8b (FAdV-8b) was successfully isolated from ducks.Cherry Valley ducks were successfully infected with FAdV-8b.Different routes of infection can lead to duck mortality, more pronounced when birds are injected intramuscularly.FAdV-8b (SDYT) was distributed in various tissues and organs of ducks, causing different degrees of lesions.

The use of copper nanoparticles (CuNP) in the diet of broiler chickens has been studied as a potential alternative to antibiotic growth promoters. This study aimed to analyse the antimicrobial properties of CuNP in the feed and water of broiler chickens against Salmonella Enteritidis and to assess the intestinal integrity and toxicity of CuNP supplementation in their diet. The antimicrobial activity of CuNP against S. Enteritidis was tested in microplates to evaluate three water samples with different mineral compositions and in an in vitro digestibility model that simulated the three primary intestinal compartments of birds to assess feed samples. To evaluate in vivo intestinal integrity and toxicity, the birds were divided into four groups (30 birds per group): (1) basal diet (control); (2) basal diet + CuNP (100 ppm); (3) basal diet + enramycin (10 ppm); and (4) basal diet + CuNP (100 ppm) + enramycin (10 ppm). Intestinal samples were collected for histomorphometric evaluation and lactic acid bacteria count, while chest muscle and whole blood samples were collected to determine copper content. A significant reduction in the S. Enteritidis count was observed in both in vitro treatments (water and feed) with CuNP inclusion, compared to the control group. No significant differences in histomorphometric measurements, weight gain, or total lactic acid bacterial counts were found compared to those in the control. These results demonstrate the effectiveness of CuNP in reducing the occurrence of S. Enteritidis and their non-interference with the intestinal integrity of broiler chickens, highlighting the potential of CuNP as an alternative antimicrobial agent in the poultry production chain.RESEARCH HIGHLIGHTSSupplementation with CuNP in feed and water reduced Salmonella Enteritidis count.Supplementation with CuNP did not affect intestinal integrity of broilers.CuNP did not affect weight gain or total lactic acid bacterial counts.The results demonstrate the potential of CuNP as alternative antimicrobials.

Nontyphoidal serovars of Salmonella enterica subsp enterica frequently colonize the intestinal tracts of chickens, creating risks of contamination of meat and egg food products. These serovars seldom cause disease in chickens over 3 weeks of age. Colonization is generally transient but can continue to circulate in a flock for many months. Vaccination of breeders and layers is the most effective method of control of infections with serovars Enteritidis and Typhimurium, and the development of these vaccines or other preventative treatments requires challenge studies to demonstrate efficacy. However, establishing a successful challenge model where the control birds are colonized to a sufficient extent to be able to demonstrate a statistically significant reduction from the vaccine or treatment is problematic. A meta-analysis of published S. Enteritidis challenge studies was performed to pursue the best challenge model conditions that provide consistent control colonization outcomes. Challenge at sexual maturity was significantly more effective in achieving at least 80% colonization of control hens.RESEARCH HIGHLIGHTSSalmonella challenge chicken models do not always achieve high colonization levels in controls.The age of hen is important in achieving good caecal colonization.Challenge around sexual maturity provides the best control colonization outcome.A challenge dose rate of 10⁵ CFU/ bird is adequate in birds under 30 weeks of age.