British Poultry Science

Brown, I. H.

doi: 10.1080/00071668.2026.2653036pmid: 42145115

1. Since 2020, H5 high pathogenicity avian influenza (HPAI) viruses of clade 2.3.4.4b have spread rapidly to all continents except Oceania. This panzootic presents an unprecedented threat to global poultry health, with severe uncertainties as to when it will peak or resolve. The complex epidemiology across multiple ecosystems creates unparallelled challenges following the spread of virus to and within multiple orders of wild birds. 2. Sustained infection in numerous species of wild mammals, together with a substantial outbreak in US dairy cattle, increases the animal health threat and elevates risk for increased zoonotic infections. In developed commercial production systems, biosecurity can still be deficient and, if not addressed, can exacerbate the problem further. 3. The virus is currently phenotypically stable but continually evolving at the genetic level and these changes need continual tracking to understand future risk and adaptive interventions. This disease not only threatens poultry production and food security worldwide but has a significant impact on biodiversity and improved tracking and knowledge of ecology in wild populations is required. 4. Vaccination is a single tool that has potential utility as part of a holistic control plan. In some countries, vaccination has been used successfully to control the disease, but global success remains limited. Improved use of best practice, tailored to practical use in multiple production systems is required for future prevention and control.

Çavuşoğlu, E.

doi: 10.1080/00071668.2025.2559394pmid: 41134346

1. Transporting animals under inappropriate conditions causes pain and suffering to the animals and causes financial loss for the producers. This study investigated the effects of the season and transportation distance on the dead-on-arrival (DOA), reject rate (due to lesions and damage) and body weight loss parameters of the broiler breeder (BB) chickens during transportation from the farm to the slaughterhouse. 2. Data was obtained by analysing two-year records of a commercial slaughterhouse in Turkey. During the period examined, 2,452,624 BB were transported and slaughtered to this slaughterhouse by 554 trucks. 3. The lowest DOA rate (0.186%) occurred in the summer season and the reject rate in summer (0.104%) was lower than in other seasons. During the monitored period, the effect of season on body weight loss was not statistically significant. When the impact of transportation distance was considered, there was more body weight loss (1.663%) in animals transported over longer distances. 4. The data highlighted how important it is to pay attention to transportation conditions of these animals to the slaughterhouse, especially under cold climate conditions and over long distances, both in terms of animal welfare and economics.

Taghipour, M.; Akhlaghi, A.; Naseri, M.; Daryabari, H.; Dadpasand, M.; Nasrollahi, B.; Farhadi, A.; Peebles, E. D.

doi: 10.1080/00071668.2025.2559400pmid: 40991233

1. Female Chukar partridges (Alectoris chukar) strategically adjust maternal reproductive strategies based on male attractiveness, which can influence both reproductive success and offspring sex ratio. 2. In this study, female-choice trials identified preferred and non-preferred males. Using a crossover design, each female was sequentially paired with the preferred and non-preferred males, separated by a two-week physiological reset interval. 3. Reproductive parameters, including daily egg production, fertility, hatchability (of both set and fertile eggs), embryonic mortality and the primary and secondary offspring sex ratios, were determined via molecular sexing and abdominal cavity examination. 4. Notably, offspring sex ratio did not deviate from 50:50 in preferred-male pairings, whereas females that mated with non-preferred males produced a female-biased sex ratio in both the primary and secondary stages. 5. In terms of reproductive performance, females paired with preferred males showed significantly higher fertility (~8%) and hatchability (15.27% and 10.63% for set and fertile eggs, respectively), while egg production and embryonic mortality remained unaffected. 6. These findings highlighted the importance of allowing female mate choice to improve productivity in commercial systems, especially where male scarcity is a concern.

Bagiyal, M.; Ahlawat, S.; Chhabra, P.; Sharma, U.; Arora, R.; Sharma, R.; Khatak, S.; Parsad, R.; Gera, R.

doi: 10.1080/00071668.2025.2562145pmid: 42266169

1. Indigenous poultry breeds, like Kadaknath and Aseel, represent invaluable genetic resources, combining unique nutritional and cultural traits. The Kadaknath breed is famed for its black, lean, iron-rich meat with high protein and antioxidant content, while Aseel is a muscular breed prized for endurance, stress tolerance and fighting abilities. Despite their economic and nutritional value, the genetic and metabolic underpinnings of their distinct traits remain underexplored. 2. This study conducted a comparative transcriptomic analysis of liver tissue from Kadaknath and Aseel chickens using RNA sequencing (RNA-seq) to uncover the molecular mechanisms driving their phenotypic diversity. The results identified 435 differentially expressed genes (DEG) linked to key processes such as lipid metabolism, oxidative phosphorylation and stress response. 3. In Kadaknath chickens, up-regulated genes, including CPT1A, PCK1, TXNRD3 and PPARGC1A, were associated with efficient triglyceride breakdown, strong antioxidant defence and optimised energy metabolism. This likely contributes to the characteristic lean, nutrient-rich meat with high protein and low fat content. 4. In contrast, Aseel birds showed elevated expression of stress response genes (MRPL18 and RPL11) and mitochondrial genes (NDUFA1, NDUFA8, NDUFB9 and PTPMT1), supporting its high energy requirements and resilience to stress, crucial for its endurance as a fighter breed. Gene co-expression network analysis highlighted critical hub genes driving these breed-specific adaptations.

Zhang, L.; Huang, Z.; Luo, M.; Zhang, X.; Tian, Y.; Huang, Y.; Li, X.; Wu, Z.

doi: 10.1080/00071668.2025.2559392pmid: 41123461

1. Copy number variation (CNV) is an important source for identifying genetic differences. This study compared the genome-wide CNV and their regions (CNVR) across 16 Chinese local duck breeds and detected key genes and pathways involved in growth and reproduction-related traits using this dataset. 2. Breakdancer, Pindel and CNVnator were used to detect reliable CNV, and HandyCNV was used to obtain CNVR. Selection signatures were analysed in meat (MD) and egg-laying ducks (ED) compared to wild ducks (WD) using fixation and differentiation index DIsv methods. A Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis was carried out to identify key pathways and related genes. 3. Principal component analysis (PCA) using CNV data clustered 127 ducks into 4 populations: WD, MD, ED and meat+egg-type ducks (MED). In total, 237,630 CNV and 6,176 CNVR were detected across these samples. Intersection analysis identified 1,384 common CNVR and 2,105 unique CNVR. The KEGG analysis showed that common CNVR were enriched in 7 basic life activity pathways, while unique CNVR were enriched in 9 population-specific pathways. Compared to WD, MD selection signatures were found in 4 enriched pathways and 8 genes (LRP2, NID1, ATP1B3, PDGFD, MAGI2, FLT1, DMD, RALGAPB) related to growth and meat traits. The ED signatures revealed three key pathways and eight genes (PRKN, CTNNA2, DLG2, PDGFD, PRKD1, RAPGEF4, EIF2S1, CRB2) linked to reproduction. 4. Using this dataset comprising 16 duck breeds, CNVR patterns were compared among WD, MD, ED and MED birds to identify common and unique CNVR. The study investigated selection signatures in MD and ED ducks and revealed key pathways and candidate genes related to growth and reproduction.

Kassa, B.; Taye, M.; Esatu, W.; Kebede, A.; Genetu, G.; Asmare, Z.; Lulie, B.; Jember, Z.; Yismaw, K.; Tesfa, A.; Girma, M.; Kebede, F. G.; Banos, G.; Watson, K. A.; Hanotte, O.; Dessie, T.

Fotouh, A.; Elbarbary, N. K.; Moussa, M. A.; Diab, M. S.; Elshafae, S. M.

doi: 10.1080/00071668.2025.2559391pmid: 40960799

1. The following reports an in-vivo study to investigate the toxicity profile of the azithromycin drug in broilers. 2. Ninety, 1-d-old Hubbard chicks were purchased from Dakahliah Poultry Company, Egypt and, on d 25 of age, were subdivided into three groups. Group 1 (G1, control) received only drinking water, Group 2 (G2, treatment 1) received 50 mg azithromycin/kg body weight (BW) and Group 3 (G3, treatment 2) received 300 mg azithromycin/kg BW. All treatments were administered orally. Immunological, histopathological, and immunohistochemical assays were performed to evaluate the effect of azithromycin on broiler health. 3. The weights of bursa of Fabricius and spleen in azithromycin-treated broilers decreased, particularly in G3. A decrease in both the phagocytic activity and index was evident in the treated groups (G2 and G3). Prominent degenerative changes and necrosis of immune organs were observed in treated chicks. Furthermore, strong immunoreactivity to caspase-3 was observed in the G3 group, which indicated elevated apoptosis in immune organs following exposure to a high-dose of azithromycin. 4. It was concluded that administering azithromycin in broilers at a dose of 300 mg/kg impaired the immune function, promoted apoptosis and induced many microscopical alterations in different organs.

Sahindokuyucu, I.; Yilmaz Cagirgan, O.; Kilic, H.; Cagirgan, A. A.; Yazici, Z.

doi: 10.1080/00071668.2025.2558993pmid: 40960490

1. Inclusion body hepatitis (IBH), hepatitis-hydropericardium syndrome (HHS) and adenoviral gizzard erosion (AGE) are poultry diseases that are caused by fowl aviadenovirus (FAdV). Identifying serotypes is crucial for differentiation. 2. Between September 2020 and May 2021, 58 FAdV strains were isolated from 278 potentially infected commercial chicken flocks in Turkey, specifically from broiler and breeder flocks located in Balıkesir, İzmir, Manisa, Çanakkale, Afyonkarahisar, Bursa and Elazığ. 3. Viruses were isolated from pooled internal organs and propagated using primary chicken embryo kidney cell cultures (CEKC) and SPF embryonated chicken eggs. Amplification by PCR of the Hexon gene, followed by Sanger sequencing, revealed three FAdV-D (serotype 11) and 55 FAdV-E (serotype 8b) genotypes. 4. For next-generation sequencing (NGS), two representative serotypes, TR/FAdV/1 (FAdV-8b) and TR/FAdV/2 (FAdV-11) were chosen. Whole-genome sequencing performed on the Illumina MiSeq platform identified both as FAdV-8b. The TR/FAdV/1 genome, measuring 44 061 bp with a G/C content of 57.9%, showed 98.1% identity with the U.S. FAdV-E strain (GB624-U.S.A.). Meanwhile, the TR/FAdV/2 genome, consisting of 43 891 bp with a G/C content of 57.88%, displayed 99.90% similarity to the Spanish FAdV-E strain (11 -16 629). Both genomes contained 36 open reading frames (ORFs). 5. Severe IBH outbreaks linked to FAdV-D and FAdV-E were marked by enlarged, pale yellow livers with petechial haemorrhages. At present, no commercial vaccines for FAdV are available locally. Understanding and characterising emerging FAdV strains is needed for vaccine development and control strategies.

Papanikolaou, K.; Kettrukat, T.; Kjærup, R. B.; Moosavi, M.; Dalgaard, T. S.; Therkildsen, M.

doi: 10.1080/00071668.2025.2564718pmid: 41123459

1. The current study investigated the effects of different egg incubation temperatures and sex on local and systemic immune parameters post-hatch in Ross 308 broilers. It was hypothesised that increased or decreased incubation temperature could support the developing immune system. 2. In total, 405 eggs from a 49-week-old breeder hens were divided into three groups and incubated between embryonic days (ED) 4–7, at different temperatures: normal/control (37.5°C), lower (36.5°C) or higher (38.5°C). After hatching, the broilers were sexed and reared for 35 d. Blood samples and tissue samples from the spleen and ceacal tonsils were analysed for various immune parameters from a sub-set of the chickens representing all treatments. 3. The results showed that the 38.5°C treatment provided significant immunomodulation by altering the number, percent and expression of surface receptors in various leukocyte subsets. However, interpreting the observed differences in terms of immunocompetence was ambiguous. The 36.5°C treatment showed a potential improvement in immune function by increasing the opsonisation potential of blood serum indicating a potential beneficial effect of the lowered temperature. 4. Regarding immunological differences between sexes, females had a higher percentage of MHC-II positive monocytes/macrophages and a higher cell surface expression of MHC-II in the caecal tonsils than males.

Imran, M.; Saleemi, M. K.; Khan, A.; Gul, S. T.; Jamil, M.; Alvi, M. A.; Yar, A.

doi: 10.1080/00071668.2025.2572079pmid: 41347283

1. Immunosuppressive disorders in poultry pose a significant threat to health and productivity. Ochratoxin A (OTA), a mycotoxin and fowl adenovirus serotype 4 (FAdV-4), the causative agent of hydropericardium syndrome and inclusion body hepatitis, are each known for their immunopathological effects. However, little is known about their combined impact on the immune system of poultry. 2. This study investigated the synergistic immunosuppressive and pathological effects of OTA and FAdV-4 co-exposure in broiler chickens. A total of 144, one-day-old broiler chicks were randomly divided into six groups and exposed to OTA (200 ppb or 400 ppb), FAdV-4, or their combinations for 35 d. The FAdV-4 inoculum was PCR-confirmed and administered subcutaneously. 3. Birds were monitored for clinical signs, mortality, feed intake and weight gain. Immune function was assessed via SRBC antibody titres, PHA-P – induced lymphoproliferation and carbon clearance assay. Gross and histopathological changes in lymphoid organs were also evaluated. 4. The OTA exposure led to dose-dependent immunosuppression, with significant reductions (p ≤ 0.05) in humoral and cell-mediated responses, lymphoid organ atrophy and phagocytic dysfunction. The FAdV-4 infection alone caused immunosuppressive effects, which were significantly exacerbated when combined with OTA. Co-exposed birds exhibited severe lymphocytic depletion, pronounced histological lesions and increased mortality. 5. The results demonstrated a synergistic immunosuppressive interaction between OTA and FAdV-4 in broiler chickens. This highlighted the need for routine mycotoxin screening in feed and molecular surveillance of adenoviral infections to prevent compounded immunosuppressive effects and economic losses in commercial poultry production.