Poultry and Avian Diseases. Encyclopedia of Agriculture and Food Systems. Elsevier; 2014. pp. 504-20. [DOI: 10.1016/b978-0-444-52512-3.00183-2]

Insights into microstructure and expression of markers of proliferation, apoptosis and T cells in the spleen of cattle egret (Bubulcus ibis)

The spleen is the largest secondary lymphoid organ with significant roles in pathogen clearance. It is involved in several avian diseases. The cattle egret is a wild insectivorous bird of agricultural and socioeconomic importance. Data related to microstructural features of cattle egret spleen are lacking. The present study investigated the gross anatomical, histological and immunohistochemical characteristics of the cattle egret spleen. Proliferation (PCNA and PHH3), apoptosis (cleaved caspase 3, C.CASP3) and T-cell (CD3 and CD8) markers were assessed. Grossly, the spleen appeared brownish red, oval-shaped and located at the oesophago-proventricular junction. Histologically, the spleen was surrounded by a thin capsule sending a number of trabeculae which contained branches of the splenic vessels. The white pulp consisted of the periarteriolar lymphoid sheath and periellipsoidal lymphatic sheath (PELS). The red pulp was formed of sinusoids and cords. The penicillar capillaries, which represent the terminal segments of the splenic arterial tree were highly branched, wrapped by prominent ellipsoids and directly connected to the splenic sinusoids, suggesting a closed type of circulation. Immunohistochemically, proliferating cell nuclear antigen (PCNA)-expressing cells were distributed with high counts throughout the splenic parenchyma, being highest within the splenic cords and PELS. Both PHH3- and C.CASP3-expressing cells revealed a similar pattern to that of PCNA, although with fewer counts. Large numbers of T cells were observed throughout the splenic parenchyma, mainly within the cords, as revealed by CD3 and CD8 immunoreaction. The present study provides a clear insight into the precise structure of the spleen in cattle egrets and thus improves our understanding about birds' immunity.

Disruption and recovery of outdoor bioaerosols before, during, and after the COVID-19 outbreak at a campus in Central China: pathogen composition, particle size distribution, influencing factors, and exposure risk

Before (2019), during (2020), and after (2021) the COVID-19 outbreak, different response methods and measures were taken on campuses to control the spread of COVID-19 within schools. These response methods may have changed the outdoor bioaerosol characteristics, which may affect staff and student health. Therefore, we analyzed the bacterial concentrations, particle size distribution, microbial populations, exposure risks, and environmental influences of bioaerosols at a campus before, during, and after the COVID-19 outbreak. This study used eight-stage Andersen samplers to collect and analyze culturable bacteria in bioaerosols from various locations, high-throughput sequencing to analyze microbial species, principal component analysis to compare differences in samples, RDA to investigate the effects of environmental factors on bioaerosols, and hazard quotient (HQ) and BugBase to evaluate human health risks. The study findings revealed that average bacterial concentrations before, during, and after COVID-19 were 75 CFU m-3, 136 CFU m-3, and 78 CFU m-3, respectively. Moreover, the average percentage of bacteria attached to PM2.5 was 49.2%, 42.7%, and 29.9%, respectively. High-throughput sequencing revealed that species composition changed significantly during the three years of COVID-19. The proportion of Pantoea and Bacillus increased with the development of COVID-19 and these became the dominant strains after COVID-19, whereas Pseudomonas had the maximum proportion during COVID-19. Both risk assessment and BugBase phenotype prediction results indicated that the potential pathogenic risk was the highest in the outdoor environment of the campus during COVID-19 and that bioaerosol contamination was the most severe compared to the outdoor bioaerosol characteristics of the campus recovered after COVID-19.

Metagenomic Characterization of Poultry Cloacal and Oropharyngeal Swabs in Kenya Reveals Bacterial Pathogens and Their Antimicrobial Resistance Genes

Poultry enteric bacterial diseases are of significant economic importance because they are responsible for production losses due to weight loss, increased morbidity and mortality, and increased cost of production arising from poor feed conversion and treatment. This cross-sectional purposive study characterized enteric bacterial pathogens in poultry from selected agroclimatic regions in Kenya and investigated their antimicrobial resistance gene profiles. Cloacal (n = 563) and oropharyngeal (n = 394) swabs were collected and pooled into 16 and 14 samples, respectively, to characterize bacterial pathogens and their antimicrobial resistance gene profiles. We report that Proteobacteria, Chlamydiae, and Firmicutes are the most dominant phyla present in both cloacal and oropharyngeal swabs of the six poultry species studied, indicating the colonization of the poultry gut by many pathogenic bacteria. Using KEGG and COG databases, some pathways related to metabolism, genetic information, and cellular processing were detected. We also report the abundance of antimicrobial resistance genes that confer resistance to β-lactamases, aminoglycosides, and tetracycline in most of the poultry analyzed, raising concern about the dangers associated with continuous and inappropriate use of these antibiotics in poultry production. The antimicrobial resistance gene data generated in this study provides a valuable indicator of the use of antimicrobials in poultry in Kenya. The information generated is essential for managing bacterial diseases, especially in backyard poultry raised under scavenging conditions.

Investigation of the Effect of Three Commercial Water Acidifiers on the Performance, Gut Health, and Campylobacter jejuni Colonization in Experimentally Challenged Broiler Chicks

This study investigated the effect of three commercial water acidifiers on the performance, gut health, and C. jejuni colonization in experimentally challenged broiler chicks. A total of 192 one-day-old broiler chicks (Ross 308^®) were randomly allocated into 6 treatment groups with 4 replicates according to the following experimental design: group A, birds were not challenged and received tap water; group B, birds were challenged and received tap water; groups C, D, E, and F, birds were challenged and received tap water treated with 0.1% v/v SPECTRON^®, with 0.1-0.2% v/v ProPhorce™ SA Exclusive, with 0.1-0.2% v/v Premium acid, and with 0.1-0.2% v/v Salgard^® Liquid, respectively. The continuous water acidification evoked undesirable effects on broilers' performance and to an increased number of birds with ulcers and erosions in the oral cavity and the upper esophageal area. ProPhorce™ SA Exclusive and Premium acid significantly reduced the C. jejuni counts in the crop, whereas Salgard^® Liquid significantly reduced the C. jejuni counts in the ceca of birds. At slaughter age, only Premium acid significantly reduced C. jejuni counts in the ceca of birds. All the tested products ameliorated the changes induced by C. jejuni infection in the pH in the ceca of birds. It can be concluded that besides the effectiveness of the tested products in controlling C. jejuni in broilers, their continuous application evoked undesirable effects on broilers' performance, leading to the need to modify the dosage scheme in future investigations.

Salt-contaminated water inducing pulmonary hypertension and kidney damage by increasing Ang II concentration in broilers

NaCl is the main component of freshwater salinization. High NaCl concentration in drinking water can cause pulmonary hypertension syndrome (PHS) and kidney damage in broilers. To explore the effect of NaCl in drinking water on broilers' kidneys, this study divided 80 chickens into four groups. With the control group fed with pure water, broiler chickens were fed with fresh water (FW, NaCl 1 g/L), low salt-contaminated water (L-SCW, NaCl 2.5 g/L), and high salt-contaminated water (H-SCW, NaCl 5 g/L). The results show that ascites heart index (AHI) and hematocrit (HCT) of broilers increase in L-SCW and H-SCW, the serum blood urea nitrogen and creatinine of broilers increase significantly, the kidney index increases, the kidney sections show vacuolar degeneration and fibrotic degeneration, and the TUNEL results show that the kidneys possess obvious apoptosis. In addition, the detection of RAAS-related genes (AGT gene in the liver, REN in the kidney, ACE in the lung) demonstrates that after using salt-contaminated water, the transcription levels of AGT, REN, and ACE rise significantly, and the concentration of angiotensin II (Ang II) also increases significantly. In order to verify the effect of Ang II on broiler kidneys, this research used exogenous Ang II to treat chicken embryonic kidney (CEK) cells. The results show that the cell activity of CEK decreased with the increase of the concentration of exogenous Ang II. Meanwhile, the flow cytometry assay shows that Ang II could promote the apoptosis of CEK cells. These results indicate that the salt-contaminated water can aggravate PHS and cause kidney damage. The mechanism may be related to the increase of Ang II.