Commercial Broiler Research Articles

DIFFERENTIATED IN VITRO LYSOZYME ACTIVITY IN AVES AND MAMMALIA IN RESPONSE TO SEABUCKTHORN (HIPPOPHAE RHAMNOIDES) STIMULATION

Lysozyme, an intrinsic component of the immune system, is a naturally occurring enzyme with antimicrobial activity (Khorshidian et al., 2022), by hydrolyzing the muramyl dipeptide in the bacteria cell wall. Considered to be an endogenous antibiotic, it differs by species (Ferraboschi et al., 2021). Some of the medicinal plants were cited to inhibit the anti-lysozyme activity and biofilm formation by bacteria (Bukharin et al., 2003). The aim of this research was to evaluate the differences in the in vitro activity of lysozyme between the classes Aves and Mammalia when treated with a protein-carotenoid extract of Hypopphae rhamnoides compared to well-known immune modulating preparations (selenium or selenium and copper compounds). The investigations were carried out on serum samples from: a) commercial broiler chickens aged 34 days (n = 19) and b) 5-month-old Supercunirom breed male rabbits (n = 19). The agar gel radial immune diffusion method and the Micrococcus lysodeicticus test strain were used to define the in vitro lysozyme activity. The sera were mixed with serial dilutions (1:2, 1:4, etc.) of the tested compounds. The groups were compared by Student’s t test for statistical significance of the results. He increase in activity (%) versus control were calculated. Sea buckthorn extract significantly (t= 7.22, p < 0.001) decreased the in vitro activity of lysozyme at both dilutions used (1:2, 1:4). The concentration of serum lysozyme was higher in rabbits than in chickens and its lytic activity was enhanced by selenium and copper combinations in chickens (183.69 ± 37.91%) and less in rabbits (128.45 ± 84.10%) in a dose dependent manner. At lower dilutions (3:4), the lysozyme activity remained below that of the control treated with saline. The protein-carotenoid extract of sea buckthorn acted inhibiting on lysozyme activity, proving the need for tailored extraction and treatment protocols depending on the bacteria and host species.

Isolation and molecular characterization of velogenic Newcastle disease virus genotype VII.1.1 from commercial broilers and wild birds in Matrouh governorate, Egypt

Isolation and molecular characterization of velogenic Newcastle disease virus genotype VII.1.1 from commercial broilers and wild birds in Matrouh governorate, Egypt

Comparative analysis of innate immune responses in Sonali and broiler chickens infected with tribasic H9N2 low pathogenic avian influenza virus

BackgroundH9N2 avian influenza viruses have been circulating in Bangladesh since 2006, affecting multiple avian species and resulting in economic losses. The recent emergence of tribasic strains, along with co-infections, has increased the risk to poultry health. Therefore, the study aimed to compare the immune responses of Sonali (crossbred) and commercial broiler chickens infected with tribasic H9N2 low pathogenic avian influenza (LPAI) virus.MethodsFollowing H9N2 infection, proinflammatory (IL-6, IL-8, IL-1β and TNF-α) and antiviral (IFN-β and IFN-γ) cytokine expressions were observed in the trachea, lungs, intestine, and lymphoid tissues in Sonali and broiler chickens from 1 day post infection (dpi) to 10 dpi by qPCR.ResultsSonali chickens exhibited significantly higher proinflammatory and antiviral cytokine expressions in the trachea at 3–7 days post infection (dpi), while broiler chickens showed lower immune responses. Broiler chickens displayed prolonged IL-6, IL-8, and IL-1β expression in lungs at 3–10 dpi compared to Sonali chickens. In the intestine, broiler chickens showed higher IL-6 and IL-8 expression that peaks at 1–3 dpi, while in Sonali chickens only IL-1β elevated at 10 dpi. In response to the H9N2 viruses, broiler chickens exhibited a stronger early IFN-β responses and a delayed IFN-γ responses in their lymphoid organs compared to Sonali chickens.ConclusionThis suggests distinct immune profiles between the chicken types in response to the H9N2 infection. The information sheds light on the function of innate immunity in the pathophysiology of currently circulating tribasic H9N2 virus and could assist in effective controlling of avian influenza virus spread in poultry and designing vaccines.

Association of Major Histocompatibility Complex Polymorphism With Acute Phase Response in Broiler Chicken.

Stress associated with changes in host immunity occurs in response to altered environmental conditions, endogenous imbalances, infectious agents and harmful stimuli. The importance of genetic diversity in chickens has increased due to individual immune differences towards resistance and susceptibility to various stimuli. This study aimed to investigate the association of major histocompatibility complex (MHC) polymorphism with acute phase response (APR) in Ross 308 broiler chickens. The allelic diversity of the LEI0258 microsatellite marker was determined in 120 Ross broilers. In addition, acute phase proteins (APPs), including serum amyloid A (SAA) and alpha-1-acid glycoprotein (AGP), were analysed as markers of the APR. Furthermore, leukocyte count and the heterophil/lymphocyte ratio (H/L ratio) were examined. The antibody response to the Newcastle disease vaccine (NDV) was also measured to assess humoral mediated immunity. Lastly, the correlation between immune responses and MHC alleles was investigated to identify the most effective alleles in a stress-related situation. A total of six alleles, ranging from 195 to 448bp, were identified. Association study revealed a significant influence of MHC alleles on APPs in Ross population (p<0.05). Notably, Allele 448 had a significant correlation with SAA concentration and the H/L ratio. Allele 207 displayed a positive association with AGP concentration, whereas Allele 195 showed a negative association. Furthermore, a significant association was observed between Allele 448 and basopenia, as well as between Allele 195 and monocytosis. Results confirmed the significance of MHC as a candidate gene marker for immune responses, which supports its use for vaccine design, genetic improvement of disease-resistant traits and resource conservation in commercial broiler chickens.

Effect of coated calcium feeding on growth performance, carcass traits, immunity, blood biochemistry and tibial bone morphometry in commercial broiler chicken.

The bone abnormalities pose great concern in heavy, rapidly growing broilers, resulting in significant economic loss, and health issues in birds. To address these problems and prevent unnecessary mineral excretion into environment, it is crucial to optimise the inclusion level of dietary calcium in broiler's diet. The calcium utilisation by the bird is also affected by its source, particle size, bioavailability etc. Hence this study aimed to study the effect of partially replacing conventional dietary calcium source with coated calcium on growth performance, immune response, carcass traits, blood calcium and phosphorus, and mineral retention in broilers. About 416 broiler chicks were randomly distributed into four treatments, each with eight replicates of 13 birds and fed with iso-calcium, isocaloric, and isonitrogenous diet for 42 days. The T0 (control) was a basal diet while the T1, T2, and T3, were treatment diets in which conventional calcium source (limestone) was partially replaced with coated calcium by 10, 20, and 30% respectively. The birds of T3 group showed higher (P < 0.05) body weight gain, better feed conversion ratio and higher carcass yields compared to T0, T1, and T2 diet fed birds. Further the treatment groups exhibited higher (P < 0.05) cell-mediated and humoral immune responses and immune organ weights compared to control. The tibial bone weight, length and average diameter was highest (P < 0.05) in T3. Moreover, the T3 diet fed group also showed higher (P < 0.05) calcium and phosphorus content in serum and bone and lowest content of these minerals in the excreta followed by T2, T1 and control. These findings suggest that a 30% conventional calcium source with coated calcium may be used as a high-grade mineral source for broiler chicken feed.

Molecular characterization of reassortant infectious bursal disease virus (IBDV) strains of genogroup A3B1 detected in some areas of Britain between 2020 and 2021

Infectious bursal disease virus (IBDV) causes a major immunosuppressive disease of chickens. As part of ongoing epidemiological surveillance for IBDV, the hypervariable region (HVR) of the VP2 capsid gene encoded by segment A, and a region of the VP1 polymerase gene, encoded by segment B, were sequenced from 20 IBDV-positive bursal samples obtained in 2020 and 2021, from 16 commercial British broiler farms. Birds had received a live IBDV vaccine at 17–22 days of age, and samples were obtained at 25–55 days of age. Of the 16 farms, none contained very virulent (vv) strains, one contained a classical virulent strain, two contained vaccine strains, and five contained sequences of reassortant strains with a vv segment A and a non-vv segment B belonging to genogroup A3B1. In eight of the farms, we identified the sequences of both genogroup A3B1 reassortant strains and vaccine strains in the same samples. Therefore, the majority of the farms (13/16 (81%)) contained genogroup A3B1 reassortant viruses. Of the flocks containing reassortant strains, 5/13 (38%) had HVR mutations Q219L, G254D, D279N, and N280T, consistent with a recently described Western European clade, but the rest had other mutations or no mutations, demonstrating that multiple clades were present in the samples. Taken together, vv strains were not detected, but reassortant strains predominated in the farms, which belonged to different clades, and were frequently found together with vaccine strains.

CFD Simulation of Dynamic Temperature Variations Induced by Tunnel Ventilation in a Broiler House.

Maintaining the optimal microclimate in broiler houses is crucial for bird productivity, yet enabling efficient temperature control remains a significant challenge. This study developed and validated a computational fluid dynamics (CFD) model to predict temporal changes in indoor air temperature in response to variable ventilation operations in a commercial broiler house. The model accurately simulated air velocity and airflow distribution for different numbers of tunnel fans in operation, with air-velocity errors ranging from -0.22 to 0.32 m s-1. The predicted airflow rates through inlets and cooling pads showed good agreement with measured values with an accuracy of up to 108.1%. Additionally, the CFD model effectively predicted temperature dynamics, accounting for chicken heat production and ventilation effect. The model successfully predicted the longitudinal temperature gradients and their variations during ventilation cycles, validating its reliability through comparison with experimental data. This study also explored different variable inlet configurations to mitigate the temperature gradient. The variable inlet adjustment showed the potential to relieve the high temperatures but may reduce overall ventilation efficiency or intensify temperature gradients, which confirms the importance of optimising ventilation strategies. This CFD model provides a valuable tool for evaluating and improving ventilation systems and contributes to enhanced indoor microclimates and productivity in poultry houses.

Microbiology, induction, and management practices to mitigate lameness caused by bacterial chondronecrosis with osteomyelitis in broiler chickens

Bacterial chondronecrosis with osteomyelitis (BCO) lameness is the most prevalent skeletal disorder in poultry, implicated by the inherent risk of the high growth rate of modern broilers. The non-synchronization of massive body mass accretion vs maturation of the structural bone induces vulnerability to bone microfracture and immunosuppression, leading to bacterial necrosis in the skeletal and thoracic vertebral bones, leg paralysis, and eventual death. BCO lameness also imposes animal welfare issues and confers food safety risks. A study in 20 broiler farms in Australia recorded 28% BCO lesions of the necropsied birds, while a study in commercial flocks in Europe reported 19% moderate-to-severe lameness symptoms. The high incidence of lameness in commercial broiler farms reduces production value and leads to a huge economic loss in the poultry industry. Managing BCO lameness in broiler poultry is more challenging than that of other species because the peak of lameness incidence emerges at the marketing age of broilers. Moreover, curative treatment of the affected broilers is arduous due to their larger populations but shorter production cycles. Thus, condemnation of clinically lame birds has been a common practice in broiler farms to prevent the transmission of highly contagious BCO throughout the broiler populations. This practice decreases the production value and increases the economic forfeits. Therefore, presenting intervention measures for managing and controlling BCO in broiler poultry is necessary. Knowledge of etiological agents, pathogenesis, detection, and experimental lameness models to evaluate the efficacy of the intervention measures is highly important in presenting approaches to mitigate BCO lameness. Thus, this review focuses on microbiology studies of BCO, models of creating experimental lameness, and intervention measures mitigating BCO lameness in broiler chickens.

Antibiotic Resistance Pattern of Lactobacillus reuteri, Lactobacillus salivarius, and Enterococcus hirae Isolated from Gastrointestinal and Respiratory Tract in Commercial Broiler Chickens

Ever since antibiotics were discovered for the treatment of bacterial diseases, an increase in antibiotic-resistant bacteria has been noticed as an economic and public health concern with a high rate of morbidity and mortality. Antibiotic resistance in broiler chickens can be a great threat to public health. This research aimed to screen commercial poultry’s gastrointestinal and respiratory tract bacteria to observe the antibiotic resistance pattern. In this experiment, gastrointestinal tract (GIT) and respiratory tract (RT) bacteria were identified using 16s rRNA gene sequencing from broiler chickens in anaerobic conditions following a bile salt tolerance assay and an antibiotic susceptibility test. Lactobacillus reuteri, Lactobacillus salivarius, and Enterococcus hirae were identified as the isolates. The bacteria found in the gut had a modest degree of bile salt tolerance. The isolates were sensitive to amoxicillin, gentamicin, and streptomycin but resistant to tetracycline, levofloxacin, metronidazole, azithromycin, and erythromycin. This study ensures that the GIT and RT of broiler chicken is a hidden source of the isolated bacteria. A large part of this bacterial population is antibiotic-resistant and reported as a public health concern.

Physical attributes and nutritional composition of meat from dual purpose (Sasso C431 and TR51) broiler breeds in Ntabazinduna, Zimbabwe.

The growing animal welfare concerns regarding poultry production have led to the rearing of slow-growing meat type chickens also known as free-range chickens. In Zimbabwe these slow-growing chickens are gaining popularity as an alternative to the commercial broiler chickens owing to their preferred sensory attributes comparatively. Little is known regarding the quality of the meat versus that of the conventional broilers. We evaluated the physical characteristics and nutritional composition of meat from dual purpose slow-growing hybrids, Sasso C431 and TR51 in comparison with the commercial broiler breed Ross 308, under intensive feeding conditions. Birds were fed the standard commercial chicken feed produced by Hamara, a local chicken and chicken feed producing company. Birds were slaughtered on days 42, 56 and 70 of life where carcass and breast yield were measured. The pH, drip loss and cooking losses were determined for all carcasses. Proximate composition (dry matter, ash, protein, fat, carbohydrate) and mineral composition (iron, zinc and phosphorus) were determined for all the meat samples. The fast-growing broiler breed had a higher breast yield; than the slower-growing breeds, Sasso C431 and TR51 breeds (P&lt;0.05). The highest cooking and drip loss were observed in the faster growing breed Ross 308 and the lowest ones for Sasso C431 and TR51 breeds (P&lt;0.05). Shear texture values were higher in the Sasso C431 and TR51 than the Ross 308 breed (P&lt;0.05). The Sasso C431 and TR51 breeds can produce more meat with a lower fat and a higher protein compared to the Ross breeds.

Physicochemical Characterization of Broiler Poultry Litter from Commercial Broiler Poultry Operation in Semiarid Tropics of India

This study characterized the physicochemical properties of broiler poultry litter (BPL) produced from intensively reared commercial broilers that were collected from 110 commercial poultry farms at the end of the production cycle (sixth week). A further 20 samples were collected from the end use point where BPL was utilized as a soil amendment by the farmers after a period of storage for improving poultry litter management practices, developing new litter treatment technologies, or enhancing its use as a sustainable resource. The dry matter (DM), moisture, ash, organic matter (OM), and organic carbon (OC) from the manure samples were 83.04, 16.96, 27.08, 72.92, and 42.39%, respectively. The pH, electrical conductivity (EC) (dS m−1), and Kjeldahl nitrogen (N) were 8.43, 5.74, and 24.2 g kg−1, respectively. The BPL from the cement floor had higher levels of P and K than the mud floor. The correlation studies revealed that the OM, C, N, and Zn had significant positive correlations; pH, moisture, and ash had positive correlations; and EC, DM, and Ca had positive correlations. The EC level of BPL negatively correlated with pH, Fe, and Mn. The N content was found to have a highly significant (p &lt; 0.01) positive correlation with the OM, OC, Ca, and Zn content of BPL, and it was found to have a highly significant (p &lt; 0.01) negative correlation with the ash content, pH, and K content of BPL. The P content of BPL showed a positive correlation (p &lt; 0.01) with the K content and a negative correlation with the Zn (p &lt; 0.05) and Fe (p &lt; 0.01) contents of BPL. Zn was found to be negatively (p &lt; 0.01) correlated with the ash content; the pH; and the K, Fe, and P content of BPL. According to the findings of this study, BPL as such at the end of the production cycle is rich in OM, nitrogen, macrominerals, and microminerals; however, at the point of utility (after a period of storage of 4 to 6 months), there was a loss of OM, N, and mineral concentrations, highlighting the importance of proper storage and composting. Overall, this study on the physicochemical properties of broiler poultry litter is crucial for improving agricultural practices, protecting the environment, and preserving the health and safety of human beings and livestock.

Risk investigation and diversity of microbial contamination during slaughter processing of yellow-feathered broiler

The cleanliness of slaughter process is very pivotal to ensure the safety of broiler products, and slaughter process is prone to cause microbial contamination since it involves a highly collaborative system including different operations. The procedures in slaughter processing are primary sources of bacterial contamination, and it is crucial for poultry industry to maximize product safety and quality by understanding the connection between bacterial diversity on chicken carcasses. The commercial yellow-feathered broiler plant was investigated to analysis the risk of microbial contamination. In this study, 16S rRNA sequencing was used to evaluate microbial diversity and microbial contamination was investigated by collecting 910 samples from different processing steps. Generally, total count of bacteria colonies ranged from 3.14 log CFU/cm2 to 5.68 log CFU/cm2, and the microbial load at yellow-feathered broiler carcass samples was significantly higher than that at environmental samples; moreover, the cutting areas were the high-risk areas of cross-contamination. In addition, the relative abundance of Actinobacteria (9.61%) at water samples was significantly higher than that at contact surfaces samples. This paper provides a valuable theoretical insight into the diversity and changes in the bacterial community during slaughter beneficial for enterprise managers further enhancing yellow-feathered chicken quality.

Effect of in ovo feeding with a multi-strain probiotic containing effective microorganisms and Zn-Gly chelate on the fatty acid profile, lipid profile, and malondialdehyde level in the serum and tissues of newly-hatched chickens

Modern poultry production strives to ensure the safety of food products by constantly improving the health parameters of birds. Multi-strain probiotics containing effective microorganisms and microelements, especially zinc in chelated form, currently play an important role in poultry feeding. We hypothesized that supplementation of chicken embryos with a multi-strain probiotic and glycine-zinc chelate may influence lipid metabolism in the serum and tissues of newly hatched chicks, leading to an increase in the body's antioxidant capacity. Therefore, the aim of the study was to assess the lipid profile, fatty acid profile and malondialdehyde (MDA) concentration in the serum and tissues of newly hatched chickens supplemented in ovo with a multi-strain probiotic and zinc glycine chelate. The experiment was conducted on 1,500 fertilized hatching eggs obtained from 36-week-old commercial broilers (Ross x Ross 308). A multi-strain probiotic and zinc glycine chelate (Zn-Gly) were administered on the 17th day of incubation. Samples of peripheral blood and tissues of the liver, small intestine (ileum), pectoral muscle, thigh muscle and yolk sac, collected on the day of hatch and at 7 days post-hatch, were used to analyse biochemical parameters and determine the malondialdehyde level and fatty acid profile. The results indicate that in ovo supplementation with a multi-strain probiotic and Zn-Gly chelate on the 17th day of incubation affects fat metabolism. Simultaneous administration of a multi-strain probiotic and Zn-Gly chelate did not increase the concentration of polyunsaturated fatty acids (PUFAs) in the muscles. In birds treated with Zn-Gly chelate, the PUFA concentration was increased in the muscle tissue in the period up to 7 days post-hatch, i.e. during the development of the chicks. Moreover, the analysis of the results confirmed that in ovo supplementation with a multi-strain probiotic and Zn-Gly chelate stimulates the synthesis of saturated fatty acids (SFAs), mainly stearic, palmitic and myristic acids, and improves the ratio of PUFAs to SFAs. The multi-strain probiotic and Zn-Gly chelate administered in ovo did not cause excessive MDA synthesis in the tissues, suggesting that these preparations reduce oxidative stress in the developing embryo and newly hatched chick.

Use of a Mobile Methodology for the Bio-Mapping of Microbial Indicators and RT-PCR-Based Pathogen Quantification in Commercial Broiler Processing Facilities in Honduras

Use of a Mobile Methodology for the Bio-Mapping of Microbial Indicators and RT-PCR-Based Pathogen Quantification in Commercial Broiler Processing Facilities in Honduras

Establishing defined daily and course doses for antimicrobials used in Pakistani broilers to enable farm-level quantification and comparison of antimicrobial use

Monitoring antimicrobial use (AMU) is crucial, as it plays a key role in driving antimicrobial resistance (AMR). Animals account for a significant share of AMU, making it essential to accurately quantify AMU exposure at the species, farm, and country levels. In Pakistan, prophylactic use of antimicrobials remains common alongside therapeutic use. This study aimed to establish defined daily and course doses for both therapeutic and prophylactic use of antimicrobials in commercial broiler production in Pakistan. A list of antimicrobial products was compiled from the daily treatment records from 100 commercial broiler farms in Punjab, Pakistan. For each active substance (AS), a defined daily dose (DDDvetPK) was assigned for treatment, prevention or both, by averaging the recommended doses of all similar AS with the same administration route. A defined course dose (DCDvetPK) was calculated by multiplying the average recommended dose by the average treatment duration for each AS, based on the Summary of Product Characteristics (SmPC). A total of 41 AS, categorized into 17 antimicrobial classes, were identified from 139 antimicrobial products. The most frequently reported AS were colistin (polymyxins) at 15.9 %, amoxicillin (aminopenicillins) at 7.5 %, neomycin (aminoglycosides) at 7.3 %, enrofloxacin (fluoroquinolones) at 6.7 %, and tylosin (macrolides) at 6.4 % of the total treatments (n = 358) reported at farms. Notably, 51 % of AS were classified as critically important for human medicine by WHO. Among AS indicated for treatment in SmPC, the defined daily doses for Pakistan (DDDvetPK) varied substantially from the European Medicines Agency (EMA) values (DDDvet), with the top deviations being Tiamulin (+147.8 %), Sulfadimidine_TMP (+111.2 %), Flumequine (+88.6 %), Spiramycin (-87.8 %), and Tylosin (-84.3 %). This study presents a list of defined daily doses and defined course doses for AMU quantification in Pakistani broilers using dose-based indicators. The observed differences between Pakistani and EMA doses, and lack of EMA doses for preventive antimicrobials, suggest using Pakistani DDDvetPK values to quantify antimicrobial usage in Pakistan. A huge variation in recommended doses was reported in SmPC. There is an urgent need to establish a list of approved veterinary antimicrobials used in Pakistan, along with harmonization in recommended doses and maintenance of standardized SmPC by the drug regulatory authorities. Setting up a national-level list of defined daily doses is crucial to accurately monitor and quantify AMU.

Integrating GWAS and transcriptomics to identify candidate genes conferring relative growth rate trait in white-feathered broiler

Broilers are a globally significant resource for food production, and their relative growth rate (RGR) has attracted increasing attention for improving broiler monitoring, feed management and feed conversion. The main objectives of this study were to identify key candidate genes affecting the RGR in white-feathered broiler by integrating genomic and transcriptomic datasets. This study reports a meta-analysis of genome-wide association studies (GWASs) using three purebred lines (n = 3,727) and 5,841,467 input SNPs to understand the genetic control of the RGR. A total of 101 associated SNPs located on 6 chromosomes were identified, 16 of which were common in the GWASs and meta cohorts. Fine mapping of a significant peak with 7 linked SNPs (r2>0.94) located within the coding region of RAP2C revealed that chr4:3474286 (C>G) among these SNPs was a highly putative causal variant (PIP=19%) and explained 2.26% of the RGR variation. Further analyses indicated that the surface expression level of the RAP2C gene in the blood, macrophage, lung tissue, and cecum tissue of commercial broiler breed (Ross) was higher than in the corresponding tissues of other egg-laying hens and local breeds. In addition, there was a significant difference in the expression of the RAP2C gene between the high (H, n =5) and low (L, n = 4) RGR groups. A total of 301 differentially expressed genes (DEGs) related to the RGR in white-feathered broiler were identified by transcriptome differential analysis between the H and L populations, among which NFKBIA, CSF1R and TLR2A were important hub genes. Furthermore, the candidate genes identified based on GWASs, meta-analysis and DEGs analysis were significantly enriched for gene ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways involved in the growth cone, integrated-mediated signaling pathway, and MAPK signalling pathway. Overall, the RAP2C, NFKBIA, CSF1R and TLR2A genes are considered the most important candidate genes influencing RGR trait in white-feathered broiler. These findings provide valuable insights into the complex system that regulates broiler growth.

Experimental infection of Clades 2.2.1.2 (H5N1) and 2.3.4.4b (H5N8) of highly pathogenic avian influenza virus infection in commercial broilers

In this study the pathogenicity, infectivity, and transmissibility of H5N1 highly pathogenic avian influenza (HPAI) clade 2.2.1.2 and H5N8 HPAI clade 2.3.4.4b viruses were evaluated in commercial broilers on days 24 and 31. The mortality rate was 100 % in both challenge viruses and in contact birds either on day 24 or day 31 which confirmed the highly pathogenicity of both clades (2.2.1.2/ 2.3.4.4b) in commercial broilers. Both clades (H5N8 clade 2.3.4.4b/ H5N1 clade 2.2.1.2 viruses) were efficiently replicate within and transmitted between commercial broilers. The H5N8-infected birds shed high titer of viruses from oropharynx and cloaca, which associated with the field spread of AIV-H5N8 in commercial broilers. Mean lesion score in both challenged clades showed similar scores, which confirmed the pathogenicity of both clades in commercial broilers’ organs (mainly spleen, cerebellum, thymus, Bursa, Lung) which confirm the neurogenic affinity of the virus. In the central nervous system, non-suppurative encephalitis consisting in multifocal areas of necrosis in cerebral hemispheres, intense spongiosis, neuronal chromatolysis and gliosis were commonly observed. In cerebrum, chromatolysis of Purkinje neurons was a common finding. In the lung, interstitial pneumonia consisting of moderate to severe increase of the cellularity (macrophages and lymphoid cells) in air capillaries and focal areas of necrosis associated with intense viral replication was commonly observed. In lymphoid tissues, including spleen, thymus, and bursa of Fabricius, multifocal areas of necrosis/apoptosis of variable intensity in mononuclear cells were present. Particularly, diffuse necrotic areas were present in the spleen. In the liver, we detected focal areas of necrosis with mild distention of hepatic sinusoids. To conclude the AIV either H5N1 or H5N8 have neurological affinity with immune suppression effect based on necrosis and apoptosis of lymphoid tissues.

PSVII-5 Heat shock protein 70 gene expression and association with morphometric and heat tolerance traits in three plumage colors of Noiler chicken exposed to acute heat stress

Abstract Heat stress is one of the most difficult climatic conditions chickens faces and is a direct result of climate change. It is important to research poultry thermotolerance because it may help find genetic lines resistant to heat stress. This study investigated the influence of plumage colors on heat shock protein 70 gene expression in Noiler chickens exposed to acute heat stress. Noiler is a dual-purpose breed developed for smallholder poultry production in Nigeria. A total of 150 birds of three plumage colors (black, brown and white) of mixed sexes were used for the experiment. The birds were raised in deep litter house separated into six groups of 25 birds each and fed with commercial broiler diets from 0-8 wk and broiler finisher diets from 8 to 12 wk old. The birds were shared into treatments in 3 x 2 x 2 factorial arrangements with 3 plumage colors (black, brown, white), two temperature regimens (Control/thermoneutral, Heat stress) and sex of birds (male, female). The heat stressed birds were exposed to 41oC for 8 h from 0600 h to 1400 h for 7 d while control group maintained a thermoneutral temperature range of 30 oC to 32 oC for the same period. At 13 wk old, two birds were selected per treatment, slaughtered and the spleen removed and stored in RNA later for heat shock protein (HSP) 70 gene expression. Data collected were analyzed with Microsoft excel code for fold expression of HSP70 gene while GLM procedure in SAS was used to determine difference in expression of gene. The relative expression of HSP70 brown plumage was greater, upregulated compared with black and white. White plumage birds in control/thermoneutral group were significantly greater in HSP70 expression than other plumage colors and heat stressed birds. Association of HSP70 delta threshold cycle (DCT) values with morphometric and heat tolerance traits were investigated (Figure 1). High negative correlations emerged between HSP70DCT expression and body weight (-0.65), body temperature (-0.73) with moderate positive correlation for rectal temperature (0.55) in black birds (Table 1). HSP70 DCT positively correlated with body weight (0.70), breast/leg circumferences but negatively with wing length, suggesting reduced surface area during heat stress and a supportive role in maintaining protein integrity (Figure 2). For white Noiler birds, HSP70DCT associated negatively with body weight (-0.94) and positively with rectal temperature during heat stress (Table 2). Thermoneutral birds were positively correlated with heat tolerance traits except temperature while heat stressed birds showed low positive correlation with respiratory and pulse rates and very low positive relationship with body and rectal temperatures (Table 4). Sex-based differences emerged, with potential compromise between HSP70-mediated growth/composition in males versus muscle maintenance in females, although leg length/circumference showed shared developmental regulation (Figure 3, Table 3). These findings highlight HSP70’s versatile roles in systemic heat tolerance mechanisms influenced by plumage color, temperature regime and sex.

Metabolomic, lipidomic and transcriptomic reveal meat quality differences among hybrid, indigenous and commercial broiler

With the improvement in living standards, breeders need to improve meat quality to meet consumers' demands. Hybrid (HB), indigenous (IB), and commercial broiler (CB) are the most essential components in consumer market. However, the difference in meat quality and underlying mechanism remains unclear. Our study found that HB showed significant differences in meat-quality performance compared with IB and CB, especially in breast muscle's shear force and meat color. Furthermore, metabolomic, lipidomic, and RNA-seq were performed to screen the critical molecular networks contributing to the performance difference. Most differentially expressed metabolites (DEMs) were significantly associated with shear force and a∗value and enriched in lipid metabolism-related pathways. The lipidomic analysis detected many differentially expressed lipids (DELs), especially between HB and CB. Most showed a positive association with a∗ and b∗ value and a negative association with shear force. RNA-seq analysis screened 275 and 497 differentially expressed genes (DEGs) in HB compared with IB and CB, and they were also highly associated with metabolism pathways and meat-quality performance. Finally, integrative analysis was conducted to screen the core DEMs, DELs and DEGs contributing to meat-quality performance. Our findings provided knowledge for molecular markers to facilitate the selection of chicken meat quality.

Dried Chlorella powder supplementation: Impact on broiler chicken growth, health, and intestinal microflora

The use of dried Chlorella as an immune and growth stimulant to enhance nonspecific host defense mechanisms or as an antimicrobial to inhibit bacterial growth has been reported. This study aimed to assess the effects of dried Chlorella powder (DCP) supplementation on the growth, health, and intestinal microflora of commercial broiler chicks, comparing a diet containing DCP with an antibiotic-based diet. A total of 120 pieces day-old Cobb 500 broiler chicks were reared at Sher-e-Bangla Agricultural University Poultry Farm, Dhaka, and randomly divided into four experimental groups of three replicates each, with 10 chicks per replication. One group was fed a control diet, while the remaining three groups were fed diets with 0.5% and 1.0% DCP, and antibiotics, respectively. Results indicated significant (P&lt;0.05) improvements in body weight and dressing percentage with DCP inclusion compared to control-fed broilers. A linear increase in body weight was observed with higher DCP levels, with birds on the 1% DCP diet achieving superior body weights (1665.13±8.82) compared to the control and antibiotic groups. Feed Conversion Ratio (FCR) and feed consumption were also significantly (P&lt;0.05) improved, with the best FCR at 1% DCP (1.37±0.01) and the highest FCR in the control group (1.45±0.00). The highest feed consumption was noted in the control group. No significant (P&gt;0.05) differences were observed in the relative weight of spleen and bursa among the groups. DCP had no significant (P&gt;0.05) effects on liver, gizzard, intestine, and heart weights. Hematological studies revealed no significant (P&gt;0.05) differences, except for Hemoglobin and Red Blood Cells (RBC), which were significantly (P&lt;0.05) increased by DCP compared to control and antibiotic groups. DCP supplementation significantly (P&lt;0.05) reduced E. coli and Salmonella sp. counts while increasing Lactobacillus sp. counts. Additionally, treatments with DCP significantly (P&lt;0.05) boosted Newcastle disease (ND) titre levels compared to the control group. The study showed that DCP can be effectively replaced antibiotics in broiler diets, enhancing growth, health, and immune response, thereby promoting sustainable and safer poultry production practices.