With the increase in commercial pig farming, there is a simultaneous increase in the use of antibiotics for prophylaxis as well as therapeutics in China. In this study, we evaluated the prevalence and resistance diversity of salmonellae isolated from feces of asymptomatic, live and slaughtered pigs. We analyzed 1,732 pig fecal samples collected over 8 months, at Henan province of China. The salmonellae were isolated and identified by PCR. They were serotyped using commercial antisera and assayed for the MIC of 16 antibiotics by broth microdilution method. The average prevalence of Salmonella was 19.4% (95% CI: 17.6–21.4). Large farms (herd size ≥1,000) were found to have a higher prevalence as compared to the small- and medium-scale farms ( p < 0.0001). The prevalence of salmonellae in samples collected from the farms [11.77% (95% CI: 10.1–13.6)] and from the slaughterhouse [45.23% (95% CI: 40.3–50.30)] was statistically different ( p < 0.0001). Uncommon serovars of Salmonella such as Agama and common serovars such as Derby and Typhimurium were isolated. High resistance (>80%) was recorded toward ciprofloxacin (100%), tetracycline (99.4%), doxycycline (97%), sulfamethoxazole (85.8%), ampicillin (81.6%), and amoxicillin (80.4%). Multidrug resistance (MDR) to four, five, and seven classes of antibiotics was recorded to be approximately 25% in the most prevalent serovar like Derby. We conclude that the presence of alarmingly high resistance, toward the critical antibiotics such as fluoroquinolones and beta-lactams, in large swine farms in China, should draw public attention. These results highlight the need for continued antibiotic stewardship programs for judicious use of critical antibiotics in animal health as well as for producing safe pork.

Summary Astroviruses are a non‐enveloped virus with large host range breadth. AstV‐associated gastroenteritis in human and animal, nephritis in chicken, gout in gosling and hepatitis in duckling pose great threats to public health and poultry industry. Since early 2020, continuous emergence of fatal goose astrovirus (GAstV) infections characterized by articular and visceral gout was reported in China. Here, we described two outbreaks of emerging gout disease in two different goose farms of central China. Two virulent GAstV strains, designated as HNKF‐1/China/2020 and HNSQ‐6/China/2020, were isolated, and the fifth passage of the isolates could cause urate crystals accumulated in the allantoic fluid and even deposited around great vessels and embryo bodies. Meanwhile, the source of these GAstV outbreaks was tracked to goose hatcheries. The prevalence of GAstV in the goose embryos with hatch failure was confirmed, and embryo‐origin HNXX‐6/China/2020 was further isolated. The complete genome of these three newly isolates was then sequenced and analysed. The results showed that Chinese GAstVs have formed two distinct groups, and the three GAstV isolates, as well as most of the Chinese GAstVs, belong to the G‐I group. There are several amino acid mutations in the three newly identified GAstVs, such as A520T, S535R, V555I and A782T in ORF1a and Q229P in ORF2, suggesting the field stains, HNKF‐1/China/2020 and HNSQ‐6/China/2020, might derive from the weak goose embryo via vertical transmission. Moreover, the phylogenetic analysis of the complete viral genome and individual viral proteins revealed that Chinese GAstV strains have been constantly evolving towards more complicated and various directions. Our study reported the recently emerging GAstV outbreaks in central China, and further analysed the genetic characteristics of three virulent G‐I GAstV isolates from commercial goose farms and goose hatchery, indicating the diverse transmission of the virus and providing a basis for developing effective preventive measures and control strategies.

Infectious bronchitis virus (IBV), an ongoing emergence enveloped virus with a singlestranded positive-sense RNA genome, belongs to the Gammacoronavirus genus in the Coronaviridae family. IBV-associated tracheitis, nephritis, salpingitis, proventriculitis and egg drop have caused devastating economic losses to poultry industry worldwide. Since the end of 2018, a remarkably increasing number of commercial broilers and layers, vaccinated or not, were infected with IBV in China. Here, we described two IB outbreaks with severe respiratory system or kidney injury in IBV-vaccinated commercial poultry farms in central China. Other possible causative viral pathogens, including avian influenza virus (AIV), Newcastle disease virus (NDV) and Kedah fatal kidney syndrome virus (KFKSV), were excluded by reverse transcription-polymerase chain reaction (RT-PCR), and three virulent IBV strains, HeN-1/China/2019, HeN-2/ China/2019 and HeN-101/China/2019, were identified. Although the gross pathologic appearance of these two IB outbreaks was different, the newly identified IBV strains were all closely related to the ck/China/I0529/17 strain and grouped into GI-19 genotype clade based on the sequencing and phylogenetic analysis of the complete S1 genes. Moreover, there are still some evolutionary distance between the newly identified IBV strains, HeN-101/China/2019 in particular, and other GI-19 strains, suggesting that Chinese IBV strains constantly emerge and evolve towards different directions. In conclusion, this study provided an insight of the recently emerging IBV outbreaks in IBV-vaccinated commercial poultry farms and identified the genetic characteristics of three virulent GI-19 IBV strains, which shows the need to carry out proper preventive measures and control strategies.