British Poultry Science最新文献

1. This study characterised the H5N8 highly pathogenic avian influenza (HPAI) viruses, clade 2.3.4.4b from backyard waterfowl selected from Menoufia governorate during 2022. Genetic and antigenic analysis of H5N8 isolates was performed and the genetic markers for waterfowl brain invasion were analysed by whole genome sequencing.2. Molecular diagnosis of field samples showed that, out of 30 tested waterfowl flocks showing respiratory and nervous symptoms of the disease, 13 duck flocks and 11 geese flocks were confirmed positive for H5N8 by RT-qPCR.3. The whole genome sequencing for four H5N8 strains were performed from duck and geese flocks. Phylogenetic analysis of the hemagglutinin (HA) gene revealed that the 2022 isolates clustered with Russian and European-like strains. All strains had a polybasic cleavage site (PLREKRRKRGLF), indicating high pathogenicity. Mutations, such as A140T, G268E, R82K, and I162M, were identified and linked to antigenic drift and adaptation.4. Brain-derived isolates showed specific HA mutations (e.g. F244L, I248S, K234R) compared to tracheal isolates, which suggested possible roles in neurotropism. Internal genes revealed mammalian adaptation markers such as 504 V (PB2), 127 V and 672 L (PA), and 133 G (PB1), with additional unique mutations observed H5N8 strains isolated from geese in 2022. Reassortment analysis for the 8 gene segments showed that H5N8 duck strains isolated in 2018 belonged to genotype G1, while the 2022 strains belonged to genotype G4. This confirmed changes after 2018 and reflecting continuous viral evolution through segment reassortment.5. Antigenic analysis revealed that the newly introduced H5N1 virus clade 2.3.4.4b is antigenically similar with H5N8 viruses from the same clade, while different from viruses in other clades.

1. This study was conducted to evaluate the effect of dietary crude protein level and protease supplementation on production performance and blood biochemical traits of aged laying hens.2. Forty Lohmann Brown hens at 68 weeks of age were fed two diets differing in crude protein levels (CP, 120 g/kg or 160 g/kg), supplemented or not with protease at 50.0 mg/kg feed. Each treatment included ten replicate cages with one hen per replicate. The study lasted for a duration of 32 weeks. Egg production performance was measured every 4 weeks and blood chemistry and electrolyte variables were assessed at the end of the study.3. Results showed that there was no interaction (p > 0.05) between dietary crude protein level and protease supplementation on any production or blood measurements. Hens fed 120 g/kg CP diet had lower (p < 0.05) production rate, egg mass, feed intake, body weight and less favourable feed conversion ratio (FCR) compared to those fed 160 g/kg CP diet. Supplementation with protease, independent of dietary crude protein level, increased egg production (+4.8 points; p < 0.05) and mass (+3.3 g; p < 0.05), blood creatine kinase (+103%; p < 0.05) and decreased FCR (-0.51points; p < 0.05) and blood phosphorus (-18%; p < 0.05).4. The results demonstrated that protease supplementation enhanced egg production performance in aged laying hens, regardless of whether they were fed CP-adequate or deficient diets. This improvement could be partially associated with accelerating energy metabolism, as evidenced by elevated blood creatine kinase levels. These findings highlighted the potential of protease to reduce dietary protein inclusion while extending laying hens' productive lifespan and enabling the development of blood biochemical signatures for exogenous protease applications.

1.This study investigated antimicrobial resistance and virulence factors in Salmonella enterica subsp. enterica serovar Thompson (SET) isolates from broilers in the Brazilian poultry industry.2. Among 44 isolates, 18.18% showed phenotypic resistance, with tetA, sul1 and sul2 genes frequently detected, while sul3 was absent. Two isolates carried clinically relevant resistance genes: blaCTX-M-1 (ESBL) and OXA-48 (carbapenemase).3. The PFGE analysis revealed five distinct clusters with low genetic diversity, which suggested a clonal dissemination pattern. One strain from cluster E showed the highest pathogenicity in broilers, underscoring the need for continued molecular surveillance in poultry production.

1. This study examined the effects of providing feed and water immediately post hatch in combination with inclusion of Neurospora intermedia biomass in chick starter diet, as a source of protein and bioactive compounds. Variables monitored were caecal microbiota, total levels of IgY, specific antibody responses to vaccination and blood leukocyte counts.2. Ross 308 chicks were subjected to two hatching treatments - immediate access to feed and water, or delayed access at 48 h. In addition, three starter diets were fed until d 10: a control diet (C), a diet with inclusion of 10% N. intermedia (N) or diet N followed by diet C (NC).3. Chicks were vaccinated against avian pneumovirus (APV) and focal birds were repeatedly blood sampled for quantification of total IgY and antibodies specific to APV in serum. Birds fed starter diet C were sampled for measures of blood leukocyte counts. Caecal microbiota were studied in birds sacrificed on d 5, 9 and 43, respectively.4. With age, microbial richness in caeca increased and there was a shift in composition, but no effects of hatching treatment or starter diet were observed.5. Neither the starter diet nor the hatching treatment affected the total IgY in serum or specific antibody responses to APV vaccination. Late-fed chicks had a significant decrease in the total amount of IgY in serum from d 2 to d 8, likely a consequence of dehydration at d 2. Early feeding did not affect any of the leukocyte populations monitored.6. In conclusion, there were no effects of early feeding or inclusion of N. intermedia on gut microbiome or the immune traits monitored. However, the absence of adverse effects of a starter diet with the fungal biomass suggested that N. intermedia is a source of high-quality protein.

1. Early identification of various poultry illnesses may be possible with deep learning techniques. Salmonellosis, newcastle disease and coccidiosis illnesses can present poor faecal scores as symptoms. A deep convolutional neural network (CNN) model known as an 'ensemble-based CNN' was constructed to identify poultry diseases by classifying healthy and unhealthy faecal images and tested on farm.2. Four distinct deep learning models; MobileNetV2, EfficientNetB0, Xception and ResNet50V2, were compared and their corresponding inference findings recorded. To identify the best results, ensemble techniques and transfer learning, using a fine-tuning approach, were applied.3. Evaluation scores for accuracy, precision and recall were used to assess the four models to determine which performed best.4. The sum-ensemble approach and weighted average ensemble algorithm achieved 99% and the majority voting ensemble achieved 98.5% accuracy, respectively.5. The Xception model outperformed the three other models in identifying type of disease. Therefore, Xception was deemed the preferred model when accuracy is the main concern whereas the ensemble approach enhanced the performance of identification.

1. This study evaluated the effects of early access to feed and water following hatch, and inclusion of Neurospora intermedia biomass (as a source of protein and bioactive compounds) in chicks' starter diet. Variables monitored were growth performance and organ development.2. A total of 432 Ross 308 chicks hatched on-farm were provided with either immediate access to feed and water (early-fed) or delayed access at 48 h post placement (late-fed). In addition, chicks were fed either a control diet (C) or a diet with 10% N. intermedia (N) until d 10, or fed N until d 6 followed by C (NC). From d 10 and onwards all chickens received the same commercial grower diet.3. Late-fed chicks had lower accumulated feed intake and BW until d 9. On d 5, the weights of all measured organs, except the bursa and spleen, were lower in late-fed chicks. At the same time point, late-fed chicks had longer intestines and lower heart weights, relative to body weight, compared to early-fed. None of these differences persisted at the end of study on d 43 when, instead, the bursa weights, both total and relative to body weight, were higher in late-fed chickens.4. During the initial period when only early-fed chicks had access to feed and water, diet C resulted in higher FI compared to diet NC, and a higher (inferior) FCR compared to dietary treatments N or NC. On d 43 relative bursa weights were higher in chickens fed diet N compared to C.5. The results suggested that chickens are capable of compensating for 48 h deprivation of feed and water post-hatch. Supplementing with fungal biomass of N. intermedia can partly replace soya protein concentrate as source of high-quality protein in diets for young chicks.

 1. The present study investigated the effects of mild mycotoxin contaminated maize with low levels of aflatoxin B₁ (AFB₁), zearalenone (ZEA), deoxynivalenol (DON) and fumonisin (FUM) on the production performance, egg quality, antioxidant capacity and immunity of laying hens.2. A total of 378 healthy, 80-week-old Hy-line brown laying hens were divided into three groups (with six replicates per group and 21 hens per replicate): basal control diet (containing 0.534 mg/kg FUM), a diet replacing uncontaminated maize with 50% (containing 24.7 μg/kg AFB₁, 37.2 μg/kg ZEA, 0.30 mg/kg DON, and 3.23 mg/kg FUM) or 100% (containing 26.5 μg/kg AFB₁, 66.5 μg/kg ZEA, 0.30 mg/kg DON, and 4.73 mg/kg FUM) mycotoxin contaminated maize, respectively, for six weeks experimental period.3. Compared to the control group, hens fed diets with contaminated maize had decreased laying rate, yolk colour and Haugh units, and increased feed-to-egg ratio. The contaminated diets reduced activities of total superoxide dismutase, glutathione peroxidase and glutathione content and increased malondialdehyde content in magnum, isthmus and the oviduct. Serum interleukin-1β (IL-1β) and IL-2 concentrations were enhanced and IL-4 and IL-10 concentrations were reduced by feeding contaminated diets.4. Therefore, feeding contaminated maize impaired the laying performance and egg quality of laying hens, negatively affected the antioxidant and immune system.

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.

1. The poultry sector is possibly the fastest growing and most flexible of all livestock sectors. At present, the main changes to the table egg production system include the gradual abandonment and closure of all cage-housing systems for laying hens, driven by animal welfare concerns and stricter legislation in many countries. In the future, keeping hens in enriched cage systems may be restricted or phased out in response to evolving animal welfare guidelines and public demand. To meet the welfare and behavioural requirements of the hens, it is desirable to choose housing on litter or housing in aviaries as a substitute for housing in enriched cages.2. The objective of this systematic review was to examine non-cage housing systems and hemp-based dietary interventions in relation to skeletal health in laying hens. This review focussed on the risks associated with alternative housing systems, particularly the increased incidence of bone fractures and the potential of nutritional strategies to mitigate skeletal disorders, including osteoporosis.3. The proportion of hens housed in non-cage alternative housing systems is currently increasing sharply but carries certain risks. One of the most significant concerns is skeletal integrity, as hens in aviaries experience a higher rate of keel bone fractures due to collisions, falls and deviations thought to be related to internal pressure. Numerous studies have shown that the incidence of keel bone damage (i.e. fractures and deviations) was greater in aviaries compared to enriched cage systems.4. Optimal skeletal health can be supported through proper nutrition, which plays a crucial role in bone metabolism. Key nutritional elements, including calcium, vitamins D, E and K, polyunsaturated fatty acids and hemp-based products, have been shown to be beneficial in preventing skeletal disorders and associated fractures due to their specific roles in maintaining bone structure and strength.

1. This study evaluated the inclusion of golden mussel meal (GMM) of varying particle sizes in broiler chicken diets on performance, bone variables, serum biochemistry and gene expression.2. Male Cobb 500 broiler chicks (n = 900) were distributed in a completely randomised design, comprising five treatments, 10 replicate pens and 18 birds per pen, aged from 1 to 42 d.3. The treatments consisted of a control diet (calcite limestone 376 μm) and treatments GMM 299, 375, 436 and 551 μm.4. From 1 to 21 d of age, GMM 375 μm improved body weight gain (p = 0.041), while GMM 551 μm increased feed conversion ratio (p = 0.009). At 40 d of age, GMM 436 μm increased the serum aspartate aminotransferase level (p = 0.046).5. At 21 d of age, the tibial Seedor index was increased in the broilers fed GMM 375 μm (p = 0.044). The femoral mineral matter (MM) content was increased in the broilers fed GMM 375 (p = 0.047). Tibial MM content was increased in the broilers fed GMM 551 μm (p = 0.047). At 40 d of age, MM content was increased in the broilers fed GMM 375 μm (p = 0.027). Femoral calcium content was reduced in the broilers fed GMM 299, 436 and 551 μm (p = 0.004) and the tibial phosphorus content was increased in the broilers fed GMM 375 μm (p = 0.003).6. In conclusion, limestone can be replaced with GMM of different particle sizes to feed broilers from 1 to 42 d of age.