Poultry

Infectious bronchitis virus (IBV) is an avian coronavirus (CoV) that belongs to the genus Gammacoronavirus and has been listed as an important disease by the World Organization for Animal Health (WOAH). It causes highly contagious respiratory, reproductive, and renal diseases in commercial poultry farms. Multiple IBV serotypes and genotypes have been identified in many countries and many detected variants do not provide cross-protection against infection, resulting in repeated outbreaks and significant economic losses worldwide. In addition, the high genetic mutations and recombination events in the prominent genomic regions of IBV, particularly in the spike glycoprotein (S) and nucleocapsid (N) proteins, are directly involved in the evolutionary processes of IBV and lead to increased pathogenicity and tissue tropism. The characterization of the different genotypes and the relationship between the structure, function, post-translational modifications (PTMs), and structural motifs will elucidate the mechanisms that promote replication and pathogenicity and affect the host’s immune response during infection. In this review, we discuss the molecular features of various IBV genes and proteins that contribute to the infection process. We also highlight the common PTMs and structural motifs that occur during protein synthesis and are essential components of IBV ecology. Full article

Influenza A viruses (IAVs) belonging to the goose/Guangdong (Gs/GD)-lineage H5Nx remain a major concern for the global poultry industry, wildlife, and humans. The hemagglutinin (HA) protein is the dominant antigenic epitope carrier within IAV, which in turn triggers substantial immunogenic responses in the infected host. The current study describes the development and validation of a highly sensitive competitive H5 ELISA (cELISA) based on a novel monoclonal antibody developed in mice immunized with inactivated virus H5N1 (A/Turkey/ON/6213/1966). The cELISA is capable of detecting the H5 antibody response to a wider range of H5-subtype viruses belonging to both North American and Eurasia lineages, including the Gs/GD H5Nx from clade 2.3.4.4b that is currently causing the highly pathogenic avian influenza outbreaks in Eurasia, Africa, and Latin and North America. The developed H5 cELISA provides a specific, sensitive, and species-independent serological assay for the rapid detection of H5 antibodies. The assay is more robust and more sensitive than the hemagglutination inhibition assay, which is the “Gold standard”. The assay can be used in serological diagnosis, serosurveillance, and vaccine monitoring of serum samples collected from different species of animals. Full article

Disease prevalence and seasonal outbreaks are challenging the poultry industry in Ethiopia. Proper and sustainable implementation of biosecurity practices is important to reverse such problems. This study was conducted in commercial poultry farms in two zones of Ethiopia to investigate farm characteristics, implementation of biosecurity practices, and biosecurity status (BS) using a structured questionnaire. The variables were grouped into three biosecurity factors, including conceptual, structural, and operational biosecurity, based on their homogeneity. Descriptive and inferential statistics were used to summarize the results. Most commercial farms were owned by males (69.7%). The majority of the farms (40.3%) were located at a distance <50 m from residential areas. Farm owners do not provide biosecurity training to their employees (68.8%), which results in poor biosecurity implementation. The mean conceptual, structural, and operational BS were 50.4 ± 11.62, 63.27 ± 10.51, and 44.69 ± 13.04, respectively, indicating operational biosecurity measurements were less implemented. Overall, the BS indicated that 40.7% of the farms have BS < 50% questing for interventions. Farm characteristics and biosecurity measurements were positively associated with BS, which shows substantial room for improvement. Owners’ education, occupation, experience, farm flock size, and training were significantly associated with BS (p < 0.05). A disease prevention strategy through biosecurity improvement is an economical means for controlling poultry disease prevalence. Full article

The welfare of laying hens in conventional caged houses has become an increased public concern, leading primary food chains, restaurants, and grocers in the United States to pledge to source only cage-free (CF) eggs by 2025 or 2030. Cage-free housing systems have been considered as a more humane alternative; however, they still come with certain challenges. One of the primary challenges with CF housing is the poor indoor air quality due to the high levels of ammonia (NH₃) and particulate matter (PM). Despite the importance of air quality in animal welfare, most studies have focused on the egg-laying stage, thereby leaving a significant knowledge gap in the pullet phase. Addressing this gap is essential to ensure the well-being of laying hens in CF housing and to help producers and researchers identify effective strategies to mitigate the impact of poor indoor air quality on the bird’s health and welfare. Therefore, the objective of this study was to (a) examine the effect of the pullets’ age on NH₃ and PM levels, and (b) find the effect of housing, litter moisture content (LMC), and relative humidity (RH) on air pollutant concentrations. The results show that the PM levels of PM_2.5, PM₁₀, and total suspended particles (TSP) increased significantly with the growth of birds from 1 to 16 weeks of age (WOA) (p < 0.01). For instance, PM_2.5, PM₁₀, and TSP levels were measured at 0.023 ± 0.003, 0.031 ± 0.004, and 0.058 ± 0.013 mg m⁻³ in the first week, and these levels increased to 1.44 ± 0.58, 2.723 ± 1.094, and 6.39 ± 2.96 mg m⁻³, respectively, by 16 WOA. In addition, PM levels measured near the perch were found to be three times higher than other locations inside the rooms (e.g., between the feeder and drinker or near the exhaust fan) (p < 0.01), as perching is one of the primary reasons for dust generation. Furthermore, a significant interaction between the age of the pullets and PM levels was found (p < 0.01), as the litter quality and the behaviors of birds were changing over time. For NH₃ levels, average daily concentrations were lower than 1 ppm at 16 WOA for all rooms due to dry litter conditions (i.e., 9–10% LMC). Additionally, RH has been shown to have a significant effect on air pollutant concentration. Overall, the results indicate that the bird’s age significantly affects PM generation and PM variation within the rooms. The variation of PM was directly affected by RH inside the house. Therefore, this research will provide valuable information for both researchers and producers to control air pollutant emissions from the pullet stage in CF housing to ultimately improve the health and welfare of hens. Full article

One of the major problems impeding the sustainable development of goose production is low egg hatchability. Thus, it is imperative to develop more efficient ways to improve the hatching qualities of goose eggs. The present study aimed to investigate the effects of changes in the temperature regime of incubation on the availability of vitamins A (retinol) and E (α-tocopherol), as well as important elements of antioxidant protection in embryos and goslings. The initial heating of eggs at temperatures of 39 and 39.5 °C during the first 24 or 36 h was used as the main factor influencing goose embryo development. The dynamics in the content of antioxidant retinol and α-tocopherol were analyzed in the liver of embryos and goslings (up to 9 days of age) using the standard regime of incubation (at 38 °C) and the prior heating of eggs (at 39 °C and 39.5 °C) in the first 24 and 36 h of incubation. The obtained results provided new information about the effect of the initial heating of eggs on the function of antioxidants in the gosling’s body. It was confirmed that the age-related changes of retinol and α-tocopherol levels in goslings are similar to those found in chicks, ducklings, and turkey-poults. In addition, the effect of an egg’s weight on hatchability was established, with the hatchability of eggs in the medium weight class being higher than that of smaller and larger eggs. The efficiency of the redistribution of retinol from the yolk to the liver in day-old goslings was higher by 6% when exposing eggs to a temperature of 39.5 °C for 36 h. The initial heating regime at 39.5 °C led to an increased hatch of goslings, and to the evenness of their hatch from eggs of different weights, approaching the hatch values of the medium class. Overall, the α-tocopherol concentration in the liver of embryos and goslings, using the starting heating of eggs, was higher than that with the standard temperature mode of incubation. At the same time, the hatch rate of goslings increased by 9–13%, and the hatchability of eggs by 10–16%. For use in the practice of hatcheries and breeding poultry farms, it is recommended that goose eggs are heated for 36 h at 39.5 °C. Full article

With an increase in the demand and production of chicken products, broilers have been bred to grow larger at a faster rate. This has led to several myopathies, one of which being white striping, which is now common to almost all broilers and is characterized as the deposition of fat within the broiler breast muscles. The purposes of this review are to examine the change in chicken production over the years, and to consider normal muscle growth physiology and the suspected pathological process and causes of white striping, as well as white striping visualization and detection in fast-growing broilers. With the increase in growth rate and size, multiple biochemical processes are affected in broilers, leading to hypoxia and inflammation, subsequent formation of foam cells from macrophages, and the deposition of fat in the form of white stripes along the muscle tissues. The negative effects of white striping include increased fat content and calories and decreased protein content, as well as reductions in palatability and drip loss. Thus, this review also explores the effects of white striping on meat quality, and finally evaluates several strategies attempted to mitigate white striping. Full article

Pecking is one of the most concerning poultry welfare issues in the layer houses, especially in the cage-free (CF) housing system. Pecking behavior may lead to severe feather pecking (SFP) and cannibalism when birds feel frustrated, stressed, and dominant over other birds. Since pecking is caused by multi-factorial problems (e.g., hormonal influence, environment, dietary composition, and genetic differences), it is very important to find optimal strategies for reducing pecking damage. The objective of this study was to evaluate the effects of pullet age and management practices on pecking behavior and to identify the optimal pecking mitigation strategy. Four climate-controlled rooms were used, each housing 200 Hy-Line W36 pullets, for a total of 800 pullets from 0 to 16 weeks of age (WOA). Pecking mitigation strategies were tested at different ages, including an isolated chamber (IC) at 14 WOA, an IC with lotion (water, aloe vera gel, tea tree oil, calendula, and methyl anthranilate), and a pecking block from 15 to 16 WOA. Data on severe feather pecking (SFP) and mortality were collected daily from 13 to 16 WOA during the pecking block, IC, and IC with lotion treatments and from 0 to 16 WOA for the entire pullet cycle of age treatment. Results show that the SFP significantly increased with the bird’s age (p < 0.01). The SFP started with 5 WOA. About 16% of birds were found with severe peck damages by 16 WOA. In this study, pecking blocks did not show a reduction in pecking order, possibly due to pecking at alarming rates. Isolating birds with SFP damages into the IC and applying lotion resulted in a significant decrease in SFP (p < 0.05) and cannibalism (p < 0.05). This study provides a reference for commercial CF egg producers to develop on-farm management strategies for mitigating pecking damage and cannibalism. Full article

Controlling infectious diseases is vital for poultry health and diagnostic methods are an indispensable feature to resolve disease etiologies and the impact of infectious agents on the host. Although the basic principles of disease diagnostics have not changed, the spectrum of poultry diseases constantly expanded, with the identification of new pathogens and improved knowledge on epidemiology and disease pathogenesis. In parallel, new technologies have been devised to identify and characterize infectious agents, but classical methods remain crucial, especially the isolation of pathogens and their further characterization in functional assays and studies. This review aims to highlight certain aspects of diagnosing infectious poultry pathogens, from the farm via the diagnostic laboratory and back, in order to close the circle. By this, the current knowledge will be summarized and future developments will be discussed in the context of applied state-of-the-art techniques. Overall, a common challenge is the increasing demand for infrastructure, skills and expertise. Divided into separate chapters, reflecting different disciplines, daily work implies the need to closely link technologies and human expertise in order to improve bird health, the production economy and to implement future intervention strategies for disease prevention. Full article

Environmental pollution has increased over the past few decades, posing serious risks to all biological systems, including the poultry sector. Oxidative stress in chickens caused by dietary, environmental, and pathological variables influences how well chickens perform as well as the quality of meat and eggs. Lead (Pb) and cadmium (Cd) are two examples of heavy metals that are harmful for chicken health. They can cause oxidative stress by increasing the production of reactive oxygen species (ROS) and reactive nitrogen species (RNS) and blocking antioxidants from protecting cells from increased amounts of free radicals. The oxidative state of heavy metals, their interactions with endogenous antioxidants, and chemical processes all affect how hazardous they are to the body. Today, scientists have investigated and applied a variety of nutritional tactics to lessen the harmful effects of oxidative stress on animal health brought on by heavy metals. Researchers have recently become interested in the chemicals because of their chelating and growth-stimulating functions, as well as the antioxidant qualities of useful plant components. The deleterious consequences of oxidative stress induced by two heavy metals on chickens is discussed in this review, along with phytogenic use as a potential intervention strategy to lessen these effects and maintain the redox equilibrium in poultry. Full article

Currently, the egg industry is experiencing a shift in demand for eggs from cage-free environments. This study aims to evaluate the egg quality parameters of white eggs laid in several different housing environments utilized in the industry. Egg quality parameters from battery cages, barren colony cages, enriched colony cages and cage-free pens were compared. Overall, most egg quality parameters were found to be different across housing environments. Battery cages produced the heaviest eggs and eggs with the highest Haugh unit (p < 0.05). Cage-free hens produced eggs with the darkest yolks, lowest Haugh units, strongest shells and highest solids percentage compared to other environments (p < 0.05). This study did not detect differences between any housing environment in shell color, shell elasticity, vitelline membrane strength or vitelline membrane elasticity (p > 0.05). Moreover, this study did not detect any differences in egg quality parameters between enriched and barren colony cages (p > 0.05). It appears that white egg-laying hens had superior egg quality performance in caged environments and that cage-free pens only improved yolk color. Furthermore, it appears that simply adding enrichments to cages does not affect any egg quality parameters. From the results of our study, we believe that current intensive environments, such as cages, are the most beneficial for white egg layer egg quality and that as the industry moves toward cage-free, new strategies will need to be developed to preserve egg quality. More research is needed, particularly evaluating free-range environments. Full article

The housing environment has become a critical issue for consumers of eggs and egg products. Therefore, it is imperative to understand how various housing environments can affect the modern laying hen. In this study, alongside the 40th NC layer performance test, four different housing environments were chosen based on industry prevalence, which include conventional cages, barren, enrichable colony cages, enriched colony cages, and cage-free environments. Hens in these environments were raised following standard feeding and lighting practices. This study found that conventional cage and enriched colony cage hens had the highest egg production level, while hens from the barren colony cages had the lowest production level. Feed efficiency followed a similar trend, where conventional cage and cage-free hens had the best feed efficiency, followed by enriched colony cage and barren colony cage hens. This study also found that conventional cage hens had the largest eggs, while cage-free hens had the smallest eggs. Cage-free and conventional cage hens had the lowest mortality rate, while hens in the barren colony cage had the highest mortality rate. From the data shown, it appears that standard, conventional cages provide white egg layers with the most optimal environment for production performance. However, a further evaluation of health and stress is needed to determine which environment provides the hen with optimal welfare. Full article

The leaf extracts of Dacryodes edulis possess high concentrations of alkaloids, saponins, flavonoids, and tannins with various biological activities, including antimicrobial, antifungal, and antioxidant activities. These activities can be used in animal production to avoid the energy lost in favor of growth and reproduction. A total of 48 Brahma hens (45 days old), weighing on average 400 ± 12 g, were randomly distributed into four dietary treatment groups (12 birds each) with four replicates per group. The control group (T0) received 0% D. edulis, while the three test groups (T0.25, T0.50, and T0.75) were given feed with D. edulis powder leaves at concentrations of 0.25, 0.5, and 0.75%, respectively, for a period of 60 days. Water and feed were supplied ad libitum. At the end of the study period (60 days), eight birds per treatment (two per replicate) were fasted, weighed, and slaughtered. Blood samples and organs were collected for analysis of growth characteristics, oxidative stress, and toxicity indices. This study revealed a significant (p < 0.05) increase in feed intake and live body weight with 0.75% D. edilus powder leaves. Abdominal fat was found to be significantly (p < 0.05) lower with 0.75% D. edilus powder leaves compared to the control group. Serum Aspartate aminotransferase activity was significantly (p < 0.05) lower in birds exposed to 0.75% D. edulis leaf powder compared to the control group. The use of D. edulis leaf powder as feed additive in feed could reduce oxidative stress and improve growth performance in Brahma. More research can be conducted on D. edilus, and it can be used in broiler feed at 0.75% concentration, which has shown a significant increase and decrease, respectively, in live body weight and serum aspartate aminotransferase activity. Full article

Avian reovirus (ARV) strains cause a variety of symptoms in chickens, including viral arthritis/tenosynovitis, a disease that has emerged as a significant cause of economic losses in commercial chicken flocks in recent years in various countries, including Egypt. Furthermore, ARV strains are frequently isolated from birds suffering from malabsorption. In the actual study, seventy-five samples were collected in 2021 and 2022 from broiler and vaccinated broiler breeder flocks at different farms in Giza Province, Egypt, with reovirus-like symptoms such as significant weight fluctuation and arthritis/malabsorption. ARV was screened using real-time PCR, and fifteen positive samples were detected (20%), which were then subjected to embryonated chicken egg (ECE) isolation and molecular characterization (11/15 sample) of a partial segment of the sigma (σ)C gene (S1-gene). Phylogenetically, nine strains were found to belong to genotypic cluster IV, with 82–89% identity with Israeli ARV 2018, and two strains belong to genotypic cluster V with a 78% nucleotide identity with Japan ARV 2021. No correlation between lesions and genotype was found. The strains under study had a low sequence identity (43–55%) when compared with various commercial vaccines belonging to genotypic cluster I (e.g., strain S1133). These findings imply that novel ARV genotypes representing clusters IV and V have recently been introduced to Egyptian poultry farms. A homologous vaccine is suggested; because this variation raises the possibility that commercial vaccines may not offer protection against circulating ARVs. Full article

The effects of in ovo injection of L-ascorbic acid (L-AA) on tissue L-AA concentrations, systemic inflammation, plasma mineral concentrations, and tracheal histomorphology of Ross 708 broilers subjected to elevated atmospheric ammonia (NH₃) levels after hatch were investigated. The four in ovo treatments included non-injected (control), saline-injected (control), or saline containing 12 or 25 mg of L-AA. The in ovo treatments were applied at 17 days of incubation by injecting a 100 μL volume of each pre-specified treatment into the amnion. At hatch, 12 male chicks were randomly allocated to each of the 12 replicate battery cages belonging to each treatment group. The cages were arranged in a randomized complete block design within a common room. All birds were exposed to 50 ppm of NH₃ at 35 days of posthatch age (doa), and the concentration of NH₃ in the room was recorded every 20 s. At 0, 7, 14, 21, and 28 doa, one bird from each cage was arbitrarily selected and euthanized for determinations of liver and eye L-AA concentrations at 0, 7, 14, 21, 28 doa; plasma nitric oxide concentrations at 0, 14, 21, and 28 doa; and plasma calcium and trace mineral concentrations at 0 and 21 doa. Tracheal histomorphology evaluations were performed at 0, 21, and 28 doa. There were no significant treatment differences for plasma nitric oxide and mineral concentrations, and for liver and eye L-AA concentrations at each sampling timepoint. In ovo injection of either 12 or 25 mg of L-AA decreased tracheal attenuation incidence at 0 doa compared to the non-injected or saline-injected control groups. Furthermore, the percentage of mild tracheal inflammation scores was lower at 28 doa in response to the in ovo injection of 12 mg of L-AA compared to the non-injected or saline-injected control groups. These results indicate that in ovo injection of 12 mg of L-AA reduces tracheal inflammation in broilers subjected to elevated atmospheric NH₃. Full article

Perching is one of the essential natural behaviors for avian species. Providing an optimal perching design (e.g., shape, dimension, and materials) for commercial poultry production is critical for maintaining bird health, welfare, and production efficiency. This review paper summarized poultry perching studies and discussed the relationship between perch design, bird welfare, and production efficiency. Providing perches at an early stage may ensure optimum use during adulthood, reduce perching accidents, and lower the risk of floor eggs in cage-free (CF) hen houses. Therefore, a perch space of 15 cm per bird is recommended for the CF hen house. Similarly, rectangular perches are preferred to circular perches as the rectangular perch provides hens with an excellent tendon-locking mechanism to prevent slipping. In addition, perches with softer materials such as polyurethane and rubber coverings are recommended to increase the contact surface on the chicken’s toes. Perching behavior (PB) promotes a musculocutaneous system and reduces the incidences of footpad dermatitis and lesions. Generally, providing perching may reduce aggression and stress in birds and improve welfare and production efficiency. In the case of broilers, it is found that the broiler perches less during the latter stage of their lives because they are comparatively heavier and exhibit a more inactive lifestyle. Studies have investigated the effect of the surface temperature of the perch on broilers’ welfare. Perches with lower temperatures help improve performance and welfare by relieving heat stress and leg issues. Overall, PB is required to improve bird health and welfare. Full article

Four wheat-based diets with either a low soluble content of non-starch polysaccharides (NSPs, 13 g/kg); low viscosity, LV) or a high content of NSPs (33.5 g/kg; high viscosity, HV), with and without exogenous xylanase (XYL), were fed to male Ross 308 broiler chickens from 7 to 21 days age. The enzyme was supplemented at 100 FXU/kg diet, and its preparation was based on endo-1,4-beta-xylanase produced by Aspergillus oryzae. Each diet was fed to eight pens, with five birds in each pen, following randomisation. Chicks fed XYL had an improved feed efficiency, hepatic coenzyme Q10, caecal butyric acid concentration, nitrogen digestibility (p < 0.05) and increased dietary ME (p < 0.001). Compared to HV, birds fed LV diets had reduced weight of proventriculus, gizzard and the pancreas and higher blood glutathione peroxidase and dietary ME (p < 0.05), but no differences were observed on nutrient digestibility and growth performance variables. This also suggests that birds may tolerate a greater dietary NSPs content; thus, further benefits may be obtained by the application of XYL in low energy wheat-based diets. Full article

The purpose of this study was to determine if adding β-mannanase to the diet can improve the quality of storage eggs from laying hens. Lightweight laying hens (36 weeks old), housed in cages with four birds each, were randomly assigned to one of two treatments: control group (diet without additives), or birds fed with 300 g/ton of β-mannanase. The experiment was carried out on a commercial farm (14 thousand birds). The study took 84 days to be completed, and each of its three productive phases lasted 28 days. On the final day of each phase, 125 eggs were randomly collected. The quality of the fresh eggs was assessed, and after each storage interval, the remaining eggs were kept and randomly divided to evaluate their quality (7, 14, 21, 28, 35, and 42 days). Analysis of variance was used to compare means considering differences at 5 and 10%. When compared to the control group, β-mannanase was able to prevent the loss of egg weight and albumen weight during storage (p < 0.05). Yolk color (palette) also improved by 2.5% (p < 0.001), while lightness, red intensity, and yellow intensity all increased in comparison to the control group by 1.9% (p < 0.001), 7.7% (p < 0.001), and 4.10% (p < 0.001). Additionally, compared to the control treatment, β-mannanase was able to lower the yolk pH and TBARS levels by 2.4% (p < 0.001). As a result, adding β-mannanase to laying hen diets is a successful method for enhancing egg quality. Full article

Billions of poultry are slaughtered globally each year to provide protein for a rapidly expanding human population. The large number of birds produced in conventional systems presents animal welfare issues during production, transport, and at the time of slaughter. While we recognise the significance of welfare issues during rearing and transport, this paper highlights the welfare of poultry at the time of slaughter. The impacts of manual handling, inversion and shackling, use of inappropriate electrical stunning parameters, and the use of aversive gas mixtures during controlled atmosphere stunning are some of the evident welfare lapses; if the entrance to the water bath is wet and not isolated, bird welfare can also be compromised during water bath stunning because of pre-stun shocks. We also highlight the use of aversive stunning methods such as carbon dioxide gas at high concentrations, which has been shown to compromise bird welfare. In conclusion, we offer some reflections on ways to improve the welfare of birds during pre-slaughter handling, stunning, and neck cutting. Full article

As previously reported, inflammatory activity initiated by intradermal injection of multiple growing feather (GF)-pulps of a chicken with lipopolysaccharide, and the subsequent periodic sampling of GFs and blood, enables the longitudinal evaluation of in vivo tissue- and systemic-inflammatory activities by ex vivo laboratory analyses. To demonstrate the suitability of this two-window approach to monitor and assess vaccine responses, two groups of chickens were immunized by intramuscular injection of mouse IgG (mIgG), mIgG in alum adjuvant (Alum&mIgG), or PBS-vehicle (Group I and II at 7- and 7- and 11-weeks, respectively). Plasma levels of mIgG-specific antibodies were monitored by ELISA for 28 days post-primary- and secondary-immunizations. To examine the cellular responses, 20 GF-pulps per bird were injected with mIgG on Day-10 or Day-5 post-primary- or -secondary-immunization, respectively. Two GFs were collected before- and at various times (0.25 to 7 days) post-injection for leukocyte population- and cytokine mRNA expression-analyses. The observed primary- and secondary-antibody response profiles were as expected for a T-dependent antigen. Leukocyte- and cytokine-profiles established in GF-pulps revealed temporal, qualitative, and quantitative differences in local naïve, primary, and secondary leukocyte-effector responses to antigen. This study demonstrates the unique opportunity in the avian model to monitor both cell- and antibody-mediated immune responses using minimally invasive techniques. Full article