The present study was conducted to investigate the pathogeneicity of Newcastle Disease Virus (NDV) genotype VII.1.1 "NDV-CHICKEN-EGY-ALEX-NRC-2020" strain in combination with Infectious Bursal Disease Virus (IBDV) "IBDV/Egypt/Qalubia/17" and/or some commercial immunostimulants (Lector ® and Orego ® ) in commercial broiler chickens. The pathogenicity studies parameters included the effects on protection, growth performance and clinico-pathological changes. The results indicated that, immunostimulants can keep maternal immunity longer where lector ® was the best; the decline in HI titers also indicates that bird groups not contract ND natural infection. The results of performance parameters after immunostimulants administration and challenged with IBDV at 14-days of age and NDV GenotypeVII.1.1 at 21-days of age in broiler chickens proved that administration of Lector ® and Orego ® solution had positive effect on average body weight gain and feed conversion rates than control non medicated groups; where the Lector medicated groups showed higher rates of average weight followed by Orego ® medicated groups. Regarding signs and mortality in infected groups IBD signs varied from mild in lector ® , moderate in Orego ® while sever signs were in non-medicated group. The mortalities began at 5 th day post-challenge (pch) in non-medicated groups with total 10-20%; while the mortalities in NDV began at 3 rd day pch in group non-medicated with 50% to reach 100% mortality rate in 7 th pch. At necropsy both IBD and NDV infection lesions were found in dead birds of all challenged groups. Chicken groups challenged by IBDV or NDV after treatment with Lector showed milder histopathological changes than Orego solution and non-treated groups showed the most sever lesions. Chicken groups challenged with both virulent IBDV and NDV either treatment with Lector ® or Orego ® solution or non-treated showed no marked difference in histopathological lesions. The results of total and differential leucocytes indicated that lector had a great high effect in WBCs levels specially lymphocytes and monocytes. In conclusion the used immunostimulants are of low value against IBD and ND virulent viruses challenge. In conclusion, is recommended to apply a strict hygienic measures and suitable vaccination programmes to protect chickens against both IBD and NDV infection as the current control and prevention regimes, including vaccines and vaccination protocol are not adequate against either single or mixed infection infections with IBD and/or ND.

Background and Aim: Respiratory viral infections have a considerable detrimental impact on animal welfare as well as significant financial ramifications in the poultry industry. Avian influenza virus (AIV) subtypes H5 and H9, Newcastle disease (ND), and infectious bronchitis (IB) are the most economically significant illnesses impacting the poultry sector worldwide, including Egypt. From January to October 2022, this study examined the presence of respiratory viral infections (AI-H5, AI-H9, ND, and IB) in 359 flocks of broiler chickens (33–38 days) in six Egyptian governorates (Beheira, Gharbia, Giza, Monufiya and Qalyoubia). Results Out of 359 flocks examined, 293 tested positive, whereas 66 tested fully negative for the four viruses tested with the highest positive results in Beheira. Out of 293 positive flocks, 211 were positive to a single virus with Beheira having the highest rate, followed by Qalyoubia, Giza, and Monufiya. NDV was found to be the highest across all governorates, followed by IBV, AI-H9, and AI-H5. Double infection was detected in 73 flocks with either H9 or ND or both H9 and IB would co-infect one another. The most common viral co-infection was H9 + IB, ND + IB, and ND + H9. Giza had the greatest prevalence of co-infection with ND + H9, H9 + IB, and ND + IB in the governorates, followed by Monufiya and El Buhyera. Only 6 out of 359 flocks were tribally infected with ND + H9 + IB in three governorates: Giza, Monufiya, and Beheira. According to the number of flocks and the month of the year, July had the fewest tested flocks (23) and both September and October had the most (48 flocks). The positive flocks were highest in October and lowest in January. Conclusion The results revealed that IBV and H9 as a single or a mixed infection had a great role in the respiratory infection in broiler. The used vaccine (regardless their origin and type) is not able to protect broiler chickens from developing infection and shedding of virus to the poultry environment. Therefore, poultry vaccines need regular evaluation, renovation in face infective field virus mutants and also, poultry farms must be adopting more biosecurity measures.

In the commercial broiler, cellulitis is considered one of the most economically prevalent problems due to the presence of the lesion leading to increased condemnations and carcass downgrading. Clinically cellulitis is a deep infection of broiler chicken skin caused by many bacterial species, mainly Escherichia coli (E. coli) and/ or Staphylococcus aureus (S. aureus), causing severe economic losses in poultry. This study was done on 14-day old broiler Ross 308 chickens subcutaneous (s.c) injected with E. coli and/ or S. aureus to induce cellulitis. Clinical signs, mortality, pathological lesion, and growth performance were determined. Hematological parameters, liver and kidney functions were also recorded. Colistin+ Doxycycline combination (Doxyforte ® ) was used to control the infection. Clinically, site of infection was appeared red, swollen accompanied with increased skin thickness, postmortem lesions in the 3 rd day post infection with s.c. yellowish suppurative exudates, pericarditis and perihepatitis were prominent E. coli infected with hepatic subcapsular hemorrhage mostly in S. aureus groups. Hematological parameters were mostly affected in all infected non-treated groups compared to negative control without significant difference. Histopathological changes of infected non-treated groups showed inflammation of s.c tissue with massive heterophils and mononuclear cell infiltration, hydropic degeneration of the hepatocytes and congested splenic sinusoids. While treated groups showed limited skin inflammatory condition at the site of injection and return of skin to normal color and thickness. Doxycycline+ colistin combination helps in reduction of lesions in treat infected birds, with marked improvement in measured parameters. We recommended active actions to prevent causes and factors helping in including cellulitis, regular lowering bird density, enhancing restrict biosecurity, modulating the vaccination timing, improving management practices, as well as application of probiotics to improve and restore good gut health.