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 ( ≤ 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. This study evaluated body weight and egg production performance of Tilili indigenous chicken from different filial generations as a result of the selective breeding.2. The base populations (G-0) were established from 3,400 one-day-old chicks, which were hatched from 12 500 eggs collected from remote villages in Sekela and Tilili districts in 2021. During the selection program, body weight was recorded at hatch and every two weeks, while egg production data were recorded from the onset of lay to 44 weeks.3. Higher 16th-week body weight and higher cumulative 24-week egg production were selection criteria of the breeding program. Accordingly, 400 hens and 40 cocks were selected based on week sixteen body weight as selection candidates for the next generations, and 200 hens were selected based on their cumulative egg production in 24 weeks after start of lay to produce the next generation.4. Body weight traits significantly ( < 0.001) increased from Generation 0 (G0) to Generation 3 (G3). At 16 weeks of age, average body weights for G0, G2, and G3 were 814.6 g, 1100.6 g, and 1369.1 g, respectively, an overall gain of 68.1% from G0. Likewise, there was a significant ( < 0.001) increment (111.5%) in 24-week egg production in the progressive generations; 39.7, 48.03, and 82.5 eggs for G0, G2, and G3, respectively. A positive association of body weight with 24-week egg number suggested both traits improved simultaneously. Mortality rate declined significantly ( < 0.001) across generations.5. Overall, the Tilili chicken breeding program had improvements in growth, egg production, and survivability. However, genetic and phenotypic evaluations are needed due to potential negative genetic correlations between traits. Furthermore, it is essential to validate the phenotypic improvements by conducting a signature selection study using whole-genome analysis to identify the genome regions influenced by the selective breeding program.

1. Duck Tembusu virus (DTMUV) envelope (E) protein, a surface-exposed structural component, plays a key role in viral entry and induction of neutralising antibodies. However, the antigenic potential of its domains and their immunogenicity remains largely unexplored.2. In this study, analyses were conducted to predict antigenic epitopes and guide construct design. Full-length E protein and domains were expressed in and baculovirus. These were used to immunise ducks. Antigenicity was evaluated as IgG titres and cytokine profiling.3. Domain III (DIII) of the E protein was the major contributor to antigenicity and is a promising subunit vaccine candidate against DTMUV.

1. The present experiment assessed the influence of feed particle size (FPS) and live-attenuated coccidiosis vaccination (COV) at one day of age on the performance, serum biochemistry, gastrointestinal tract (GIT) development and meat quality of broiler chickens.2. The experiment employed a 2 × 2 factorial design of treatments, with two types of FPS (fine and coarse) and two COV programs (with and without vaccine) with six replicate pens per treatment each containing 20 broilers.3. Cereals were passed through 4 mm and 8 mm sieves to create feed mixtures with finely ground (FGF) and coarsely ground (CGF) particle sizes, respectively. Broiler maize, wheat and soybean diets were provided from d 1 to 13, 14 to 26 and 27 to 39 of age, respectively.4. At d 13, 26 and 39, birds fed on CGF had higher body weight and weight gain ( < 0.01) compared to those receiving FGF. During the starter period, vaccination increased FI in chicks fed FGF; however, this effect was not observed in birds fed CGF (FPS × COV interaction;  < 0.01). At all control points, significant FPS x COV interactions ( < 0.05) were noted for feed conversion ratio (FCR) with COV negatively impacting FCR only in the FGF-fed broilers.5. Serum biochemistry and GIT characteristics tended to be affected by COV. However, birds fed on CGF had relatively shorter and lighter small intestines compared to those consuming FGF ( < 0.01). The water holding capacity in breast meat decreased in relation to COV ( < 0.01).6. The results indicated that coarse grinding of feed was more effective in accommodating COV-induced growth retardation in broilers when compared to fine grinding.

1. The current study investigated the effects of different egg incubation temperatures and sex on local and systemic immune parameters -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.

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 (, , , , , , , ) related to growth and meat traits. The ED signatures revealed three key pathways and eight genes (, , , , , , , ) 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.

1. This study measured the changes in weight, size, ash, calcium and phosphorus in the skeletons of growing broilers. Ross 308 broilers were sampled at intervals from hatch to 85 d of age. The selected birds were weighed individually, killed by cervical dislocation and defeathered.2. The skeleton of each bird was excised and defleshed and divided into its component bones which were weighed before and after drying and defatting. The length and width of the metatarsus, ulna, humerus, tibia and femur were measured. The ash content of each component of the skeleton was determined. Ca and P contents were measured in the humerus, tibia and pelvis ash of three birds of each sex.3. Gompertz parameters were determined for the feather-free body and for each of the components. Rates of maturing were maintained for all components within a sex, as these are allometrically related. The slope of the plots of the natural logarithms of skeleton ash and feather-free body weight suggested that the ratio between these increased with age and were predicted using allometry.4. Tibial Ca and P formed a constant proportion of ash in the tibia but these proportions were lower in the humerus and pelvis. Hence, caution must be applied when extrapolating tibia values to the contents of the entire skeleton. The proportion of ash found in the skeleton components changed as the broiler grew, which was in a manner that was predictable using allometry with body protein. Fluctuations in the ratio between ash and body protein over the growth period suggested that birds may not be reaching their potential skeleton mineralisation with the feeds provided.

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.

1. () is a Gram-positive bacterium and a significant foodborne pathogen that causes listeriosis and occurs in animal products and other foods. Information on the prevalence of in poultry carcasses at abattoirs across Taiwan is limited.2. This study investigated contamination in poultry carcasses at abattoirs across Taiwan from 2014 to 2024, covering chickens (2014-2024), ducks (2019-2024) and geese (2020-2024) slaughter lines.3. In 2014, 20% of post-chill chickens tested positive for (95% CI: 15.1-25.6). Following government intervention and mandatory monitoring across 2014-2024, the prevalence declined steadily and was 0% in 2022-2024. Among all chicken isolates, 73 samples (56.6%) were identified as serogroup 1/2a, 3a; 26 (20.2%) as serogroup 1/2b, 3b; 2 (1.6%) as serogroup 1/2c, 3c; 2 (1.6%) as serogroup 4b, 4d, 4e; and 26 isolates were non-typable. Among all poultry species examined, ducks showed in 0.7% (95% CI: 0.0-3.9) of samples in 2019 and 0.5% (95% CI: 0.0-2.7) in 2020; both isolates belonged to serogroup 1/2a, 3a.4. Among all poultry species examined, geese had detection rates of 0.9% (95% CI: 0.0-4.7) in 2020 and 0.8% (95% CI: 0.0-4.6) in 2021. One sample was identified as serogroup 1/2a, 3a, while the other was classified as serogroup 4b, 4d, or 4e.5. Since is commonly linked to animal-derived and ready-to-eat foods, nationwide surveillance at abattoirs, together with official controls and industry improvements, is crucial for ensuring food safety.

1. Traditional methods of assessing egg freshness, such as sensory evaluation and specific gravity testing, are labour-intensive and destructive. However, non-destructive testing (NDT) technologies offer significant advantages in terms of speed, accuracy and non-invasiveness, enabling real-time monitoring of egg quality during production, transportation, storage and sale.2. A review was conducted to evaluate various NDT techniques, including optical methods (such as visible - near infrared spectroscopy and hyperspectral imaging), acoustic methods (such as ultrasonic transmission and reflection analysis), electrical methods (such as dielectric spectroscopy) and emerging technologies (such as low-field nuclear magnetic resonance, electronic nose and infrared thermal imaging).3. These technologies have advanced significantly in accuracy and real-time performance. Among optical methods: visible - near infrared spectroscopy (R  = 0.90) and hyperspectral imaging (R  = 0.918). Acoustic technologies: ultrasonic phase velocity correlated significantly with Haugh unit (HU)/air cell height ( < 0.05), with a HU model correlation of R  = 0.87. Electrical methods: dielectric spectroscopy + algorithms achieved 100% classification accuracy; capacitive sensing + machine vision yielded R  > 0.994. Emerging technologies enhanced sensitivity. However, challenges remain in terms of equipment cost, sample variability, lack of unified standards and the integration of multi-source data with artificial intelligence.4. The widespread application of these technologies can be expected to significantly improve the efficiency, safety and sustainability of the egg supply chain.

1. The current study analysed Marek's Disease virus (MDV) strains, genome characteristics and associated pathology, with reference to the central nervous system, in naturally occurring field cases across India.2. A total of 179 birds, aged less than 18 weeks, with visible visceral tumours in any of the organs were collected from major poultry areas of India. The source flocks were all vaccinated against MDV. Gross, cytological and histopathological examinations were conducted, alongside PCR for detecting MDV in lymphomatous tissues and the brain. The genetic characterisation and phylogenetic analyses of gene were conducted.3. The liver and spleen were affected in all cases, followed by the proventriculus, kidneys, heart, lungs, pancreas and sciatic nerves. Histopathologically, infiltration of pleomorphic lymphocytes was observed in affected organs, including the brain.4. All the cases were PCR-positive for the MDV genome, including four cases involving the brain. Four representative full-length sequences of the MDV gene from the brain exhibited amino acid substitutions (A-E-Y-R-V-C-P-P-T-P-L) at key positions, characteristic of virulent MDV strains.5. The findings indicated the circulation of virulent strains among MDV samples from India, based on sequence analysis and pathology involving the brain. Field isolates from the sampled locations were virulent forms of MDV and under positive selection, leading to varied tissue tropism, such as brain affinity, which has been previously reported in virulent MDV.6. The study highlighted the emergence of neurotropic, virulent MDV strains in India, underscoring the need for vigilant surveillance and revised vaccination strategies. Brain involvement in naturally occurring field cases suggests expanding tissue tropism with potential implications for diagnosis and disease control.

1. Fowl cholera poses a significant challenge for poultry farms around the globe. The disease's high mortality in poultry affects economics for farmers.2. A susceptible-exposed-symptomatic-asymptomatic-treated-culled-recovered (SEIATCR) mathematical model was used to describe the dynamics of cholera transmission in poultry farms. This calculated the basic reproduction number (R_0) using a next-generation matrix; a mathematical tool used in population dynamics and epidemiology to calculate the basic reproduction number (R₀).3. The SEIATCR model was replicated using the Runge-Kutta-Fehlberg Method (RK-45) numerical process using the value of the model's parameters available from the reported literature.4. The results showed that treatment and culling had a significant effect on disease transmission. Moreover, treatment was more effective than culling. Sensitivity analysis of the model's parameters for the basic reproduction number was investigated using partial rank correlation coefficients (PRCC), which showed that transmission rate and vaccine efficacy had the greatest sensitivity index and treatment rate is more sensitive than culling. In epidemiology, a sensitivity index is a numerical value that enumerates the impact of changes in a model's parameters on the model's output, such as disease transmission.5. There will always be a need to vaccinate, treat and cull infected poultry to control cholera in poultry farms.

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.

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 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.

1. The nutritional potential of Faba bean ( L.) is limited by the presence of phytate, which reduces phosphorus (P) digestibility and the bioavailability of other minerals. This study evaluated the effect of autoclaving and phytase on the P digestibility of broiler chickens.2. Diets were formulated to include faba beans (FB) or autoclaved FB (AFB), with or without 1,000 FYT/kg phytase, in a 2 × 2 factorial arrangement. Broiler chickens were fed a similar starter diet until d 18, after which 256 chickens were weighed and assigned to four diets in a randomised complete block design, with body weight as the blocking factor (eight replicates of eight birds per cage).3. Phytase increased the apparent total tract digestibility of P ( < 0.01), with an interaction between autoclaving and phytase on AID of P ( < 0.01); the AID of P increased to a greater extent when phytase was added to non-autoclaved FB than to autoclaved FB. Additionally, ileal digestible P and retainable P intake increased with phytase supplementation ( < 0.01).

1. In recent years, tannin has been used as a natural alternative to antibiotics due to its wide availability, ease of large-scale production and efficient extraction from other plants, compared with foreign additives such as plant essential oils and organic acids.2. Tannins are secondary metabolites widely existing in plants as a natural defence mechanism, which exhibit various bioactivities. In poultry, appropriate addition of tannins can enhance the growth performance and play a positive regulatory role in intestinal health, but inclusion in diets is limited by the bitter taste of tannins. However, 1 g/kg tannin in feed significantly reduced the final body weight of broilers and disrupted normal morphology in the intestinal tract.3. Data indicated that the effect of tannin was significantly influenced by its source and dosage, but these differences need to be confirmed. However, there is data showing tannin regulation of intestinal health in poultry, providing practical ideas on mechanism of action and commercial applications.

1. Liver-enriched antimicrobial peptide 2 (LEAP2), ghrelin and growth hormone secretagogue receptor (GHSR) are critical components of the appetite regulation system. This study analysed changes in LEAP2-ghrelin-GHSR expression across diverse feeding conditions and body weights in adult broilers and investigated the effects of intraperitoneally injected LEAP2 and ghrelin peptides on the feed intake of chicks.2. In adult broilers, the expression of in the liver and intestine exhibited significant variations under different feeding conditions (fed, fasting and refeeding), with a notable reduction observed during fasting. Compared to the fed group, proventriculus and hypothalamus gene expression doubled, but was not statistically significant. Serum analyses revealed that fasting significantly decreased LEAP2 levels relative to the fed state and a significant negative correlation was identified between LEAP2 levels and body weight in fasting chickens. Conversely, ghrelin levels remained stable irrespective of feeding states and showed no correlation with body weight.3. Intraperitoneal injection of LEAP2 mature peptide, comprising the N-terminal 14 amino acids significantly reduced feed intake of chicks within the initial 4 h. In contrast, ghrelin injection resulted in a decrease in feed intake during the first 30 min. However, prior administration of ghrelin followed by LEAP2 mitigated the suppressive effect of ghrelin on feed intake within this timeframe.4. This study demonstrated that chicken LEAP2 gives a more sensitive feedback factor than ghrelin under different feeding conditions in adult broilers. It revealed that LEAP2 in a chick model modulated feed intake. These findings provide a theoretical basis for exploring the underlying mechanisms of LEAP2-mediated feed intake regulation in poultry.

1. Female Chukar partridges () 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.

1. The presence of fractures or cracks in eggshells represent a significant risk in terms of food safety. Bacteria and viruses are likely to enter through these cracks, which increases the risk of food poisoning. Furthermore, deformations in the shell can compromise the integrity of the protective shell, rendering the egg more susceptible to environmental damage and accelerating deterioration.2. In order to mitigate these risks, a convolutional neural network (CNN) integrated into an acoustic signal to image conversion was developed as a crack detection system. Mechanical and electronic sub-systems were designed to generate non-destructive acoustic excitation on the eggshell and capture the resulting sound with a high-sensitivity microphone.3. The recorded 1 × 731-sample signals from 120 intact or cracked eggs were subjected to variational mode decomposition (VMD) to extract intrinsic mode functions (IMF). Subsequently, IMF were converted to greyscale images and classified using the proposed acoustic signal-to-image conversion and the lightweight CNN.4. The proposed model showed the capability (100%) to distinguish between intact and cracked eggs, including invisible micro-cracks.

1. Heat stress negatively affects animal growth. This study examined the impact of heat stress on a modern broiler (Ross 708) chicken compared to a heritage meat-type chicken line (UIUC).2. To mimic the effects of a heat wave, birds were exposed to daily, cyclic high ambient temperatures between post-hatch d 21-42, while control birds were maintained at thermoneutral temperature throughout this period.3. On d 28 and 42 post-hatch, eight heat-stressed and eight control birds from both lines were weighed, necropsied and total organ masses were determined for the brain, breast muscle, liver, small intestine, and spleen.4. Normalised tissue mass at d 42 under thermoneutral conditions for the Ross 708 breast muscle was 2.4-fold larger than that of the UIUC chickens. The cross-sectional area of the Ross 708 breast muscle cells was also twofold larger than that of the UIUC birds. In contrast, UIUC birds had larger heart, spleen, duodenum, jejunum, ileum and brain masses than the Ross 708 chickens when raised at the thermoneutral temperature.5. These results indicated that heat-stress shifted growth resources away from immune, skeletal muscle, neuronal and hepatic systems to maintain the heart and small intestine.

1. This study assessed the effects of injection of Marek's disease vaccine (MDV), alone (control) or combined with 1.25 μg of 25-hydroxycholecalciferol (25(OH)D), on hatchability, chick quality, performance and bone quality in Cobb 500 broilers. At d 19 of embryo development, eggs were injected with 0.05 ml of MDV or MDV plus 1.25 μg of 25(OH)D into the amniotic fluid following hatchery protocol. Post-hatch, 840, one-day-old male chicks were reared until d 35 of age.2. Hatchability and general chick quality were not affected by the treatments. However, the male chicks that received MDV + 1.25 μg of 25(OH)D presented longer length at flock thinning compared to those that received only MDV. At 35 d of age, broiler performance, gait score and leg deformities (valgus and varus) were not affected.3. Although chicks receiving the MDV + 1.25 μg of 25(OH)D had lower macroscopic tibial dyschondroplasia (TD) scores at 7 d of age compared to those given MDV, this difference was not sustained as they matured. Tibia weight, thickness and length were similar across treatments at all time points. However, the tibiae from chicks in the MDV + 1.25 μg 25(OH)D group demonstrated greater strength on d 1 and 7 but not at later times.4. In conclusion, this study showed that combining 25(OH)D with MDV does not impact hatchability or overall performance but does enhance early bone strength and growth in broiler chicks.