Journal of Poultry Sciences and Avian Diseases

The use of synbiotic additives in chicken feed improves gut microbiota and represents a promising approach to bolster protective immunity against infectious diseases and enhance production efficiency. These additives, which encompass probiotics, prebiotics, and synbiotics, are essential in modulating the microbiota of the chicken, thus promoting gut health. This narrative review aimed to explore the application of synbiotic feed additives to enhance gut microflora and mucosal immunity to disease control and improve production efficiency in chickens. In poultry production, infectious diseases are among the major challenges. Chickens may acquire these diseases either from external sources or from opportunistic pathogens that normally exist within their bodies. Most commensal bacteria reside in the gastrointestinal tract, where they form the gut microbiota. This microbiota, which begins to establish immediately after hatching, is essential for the health and well-being of chickens. The gut microbiota includes both beneficial and opportunistic pathogens. While medications are used to control infections and promote growth, excessive antibiotic use in poultry disrupts this balance, leading to negative health effects. To promote a balanced intestinal microbiota in chickens, beneficial microbes can be provided through synbiotic feed additives. This strategy can improve gut health for better nutrient absorption, strengthen mucosal-associated lymphoid tissue to enhance immunity, and potentially reduce reliance on antibiotics. Synbiotics generally have beneficial effects on host biological functions, acting as immunomodulators and promoting growth in chickens. They help limit pathogen colonization and enhance overall performance. Therefore, poultry producers should be encouraged to incorporate synbiotic-based feed supplements.

This review explores histomoniasis in poultry, focusing on its epidemiology, pathogenesis, clinical manifestations, risk factors, diagnostic methods, and control strategies. We analyzed recent literature on histomoniasis published between 2014 and 2024 using a narrative review approach. Articles were selected based on their relevance to the disease's epidemiology, clinical signs, diagnosis, and control measures. Histomoniasis, caused by Histomonas meleagridis, primarily affects turkeys and chickens, showing significant geographic variations in prevalence. The disease is transmitted through contaminated earthworms, with environmental factors such as moisture and soil type playing a crucial role in its transmission dynamics. Clinical signs include lethargy, diarrhea, and liver lesions, which can lead to high mortality rates, especially among young birds. Pathological findings typically reveal necrosis in the cecum and liver, and if left untreated, the infection can cause severe tissue damage. Various risk factors, including farming practices and co-infections, contribute to the spread and severity of histomoniasis. Diagnosis often relies on clinical signs, histopathology, and molecular methods, such as PCR, although early detection can be challenging. Control measures include antimicrobial treatments, biosecurity practices, and ongoing research into vaccines. However, existing solutions face limitations in terms of resistance and efficacy. Histomoniasis remains a significant threat to poultry health, influenced by farming practices, environmental conditions, and the presence of intermediate hosts. While antimicrobial treatments and management practices provide some level of control, further research into diagnostic tools, alternative treatments, and vaccines is essential for effective long-term disease management. Comprehensive control strategies, including enhanced biosecurity and preventive measures, are vital for reducing the impact of histomoniasis on poultry farms.

Restrictions on the use of antibiotic growth promoters in broiler chickens have stimulated the search for alternatives, such as probiotics and enzymes. Bacillus has benefits for intestinal microbial balance and productive performance; however, less is known about the effects of the enzyme glucose oxidase (GOx) in chickens, and there is scarce information about the combination of both additives on broiler performance and cecal microbiota. Chickens supplemented with either Bacillus (10⁶ spores/g feed), GOx (100 U/kg feed), the combination of both, or a control group were evaluated. Improvements were observed in performance parameters and gut health, with a reduction in intestinal IgA concentration in the treated groups; however, no difference was noted in gut permeability (serum FITC-d concentration). Bacillus and GOx alone increased the cecum microbial Alpha diversity; meanwhile, the Beta diversity from the Bacillus group was different from that of the control and Bacillus-GOx groups. A reduction in harmful bacteria (Proteobacteria) along with an increase in beneficial bacteria (Firmicutes and Actinobacteria) was observed in the cecal microbiota composition from the treated groups. GOx treatment increased the phylum Actinobacteria. Bacillus and GOx can enhance the gut health of chickens by modulating the gut microbiota. However, no synergic effect was seen in the group receiving the additive combination. Further research is needed to more effectively demonstrate the effect.

To investigate the potential of the chasteberry (Vitex agnus-castus) leaf powder (CLP) as a new phytobiotic additive in broilers' diet, 600 one-day-old Cobb 500 broiler chicks were randomly distributed among five experimental groups with four replicates (30 birds/replicate). During the rearing period, one of the following additives was added to the diet of each experimental group: No additive as the control group, antibiotic (Erythromycin) at 0.025% of the diet, 0.3, 0.6, or 0.9% of CLP. The birds were kept under the same management and rearing conditions for 42 days. During the rearing period, the birds were fed starter, grower, and finisher diets from 1-12, 13-24, and 25-42 days of age, respectively. Performance traits, including feed intake (FI), body weight gain (BWG), and feed conversion ratio (FCR), were measured for the entire period (d 1-42) of the study. Also, the status of the immune system, some ileal bacterial count, and jejunum morphology were evaluated. The findings indicated that dietary inclusion of different levels of CLP had detrimental effects on broiler performance, such that FI and BWG decreased while FCR increased (P<0.05). No significant difference was observed between the control and CLP groups in view of Ig M, Ig Y, and Total Ig titers against SRBC (P>0.05). Dietary inclusion of 0.3 % CLP decreased ileal E. coli count compared to the control group (P<0.05). Jejunum morphology (villus height, crypt depth, villus height/crypt depth ratio) was not influenced by experimental treatments (P>0.05). In conclusion, dietary supplementation with 0.3, 0.6, and 0.9 % CLP had no significant effect on immunity and jejunum morphology but negatively influenced broilers' performance traits and thus could not be recommended as a phytobiotic additive. Investigation of the effects of lower levels of CLP is recommended for future studies.

Oak fruit is high in energy and, therefore, can be used as a substitute for corn in poultry diets. However, one limitation of oak fruit is its high level of antinutritional compounds (tannins). This study investigated the effects of corn replacement with oak acorns on performance traits and the mRNA levels of hypothalamic genes in broiler chickens. For this purpose, a total of 264 one-day-old broiler chickens were randomly assigned to three experimental treatments (0, 15, and 20 % oak acorn). Body weight gain, feed intake, and feed conversion were calculated on a pen basis at 21 and 42 days of age. The results showed that body weight gain and feed conversion were significantly affected by treatments at both 21 and 42 days of age; however, no significant difference was observed in feed intake among the treatments. At the age of 21 days, a significant difference in weight gain was observed among the three treatments, whereas this difference was not significant for the treatments with oak acorn on day 42. However, the lowest weight gain was observed in the 20% oak acorn diet at both ages. Feed conversion was significantly higher in 20% of the oak acorn treatment relative to the control group on day 42, while feed conversion was not affected by treatments at the age of 21 days. In addition, the mRNA levels of NPY, AgRP, and Ghrelin were significantly downregulated in the hypothalamus tissue of broilers fed diets containing oak acorn. At the age of 21 days, the expression levels of NPY showed a significant decrease in the hypothalamus tissue of broilers fed with 15% and 20% oak corn diets, while this decrease was significant for the AgRp and Ghrelin genes on day 42. In conclusion, these results suggest that replacing 15% and 20% of corn with oak acorn can negatively affect the performance and hypothalamic gene expression of broiler chickens.

Chickens play a vital role in supplying eggs and meat. Chicken production is expanding rapidly to meet the growing demand for human nutritional needs. Nevertheless, backyard husbandry chickens are susceptible to nematode parasites and continue to sustain substantial populations. A cross-sectional study was conducted from March 2023 to February 2024 to determine the prevalence of ascaridiasis and assess the availability of anthelmintic drugs for managing chicken health. Fresh fecal samples from 380 chickens were directly collected from the cloaca using gloves and preserved in 10% formalin to conduct the flotation technique. In addition, postmortem examinations were done on 30 chickens, and adult parasites were collected to evaluate the parasite load of the chickens. Additionally, 120 farmers were interviewed to analyze the use of anthelmintic drugs for parasitic infections in their chickens. Data analysis was performed using SPSS to explore the risk factors involved. The results revealed that the prevalence of chicken ascaridiasis was 41.07% (N=115/380). Sex was identified as a significant factor, with a prevalence of 34.03% in females compared to males (χ² = 4.29, p = 0.038). Local breeds showed a higher prevalence (45.63%) compared to exotic breeds (24.55%) (χ² = 15.81, p < 0.001). Regarding management practices, the prevalence was 35.3% under extensive, 33.45% under semi-intensive, and 19.84% under intensive systems (χ² = 4.994, p = 0.025). Multivariate logistic regression analysis indicated that age (χ² = 9.915, p = 0.002), sex (χ² = 4.29, p = 0.038), breed (χ² = 15.81, p < 0.001), and management type (χ² = 4.994, p = 0.025) (OR = 1.521, 95% CI: 0.85–2.7) were significantly associated with the prevalence. Among the 30 chickens necropsied, intestinal parasite counts varied: 50% (15/30) had 1–5 parasites, 36.67% (11/30) had 6–10, and 13.33% (4/30) had 11–15 parasites in their intestines. Adult parasites were found in the small intestine, and notably, pathological lesions of varying degrees, including mild ulcerations, were present in 50% of the chickens (N = 15/30). Herbal remedies were commonly used by farmers for poultry health management, with full reliance on backyard systems (100%), followed by 90% in semi-intensive and 80% in intensive systems. These findings emphasize the importance of anthelmintic drugs for chickens' seasonal deworming programs for the effective management of Ascaridia galli.

The avian scleral ring is a critical structure for ocular biomechanics and taxonomic studies, yet its morphology in raptors remains understudied. This study investigated the scleral ring in the common buzzard (Buteo buteo) using a multimodal approach: CT, micro-CT, radiography, and anatomical dissection. Analysis of five adult specimens revealed a semi-hyperbolic ring composed of 15 quadrilateral ossicles arranged in a Type B pattern (one plus and one minus excellent ossicle), with a mean anterior-posterior to width ratio of 1.32. Micro-CT imaging showed that 53.36%±1.89 of each ossicle’s volume was compact bone, suggesting biomechanical reinforcement against flight-induced stresses. The ring exhibited complete anatomical independence from adjacent cranial bones (frontal, jugal, lacrimal) and perfect bilateral symmetry (p>0.05). High-resolution micro-CT scans resolved microscopic articular interfaces and trabecular architecture non-destructively, validating its utility for delicate orbital studies. These findings provide morphometric benchmarks for comparative anatomy in Accipitriformes, demonstrate the efficacy of non-invasive imaging for species differentiation, and offer diagnostic criteria for ocular trauma management. By integrating macroscopic dissection with advanced tomography, this work establishes a framework for evolutionary, clinical, and conservation-focused studies of avian visual systems.

The Saker Falcon (Falco cherrug), an endangered species, faces threats from diseases associated with captivity, such as amyloidosis. This study reports the first documented case of systemic AA amyloidosis in a captive Saker Falcon in Iran, linked to chronic pododermatitis (bumblefoot) and visceral gout. A female falcon with a low body score, anorexia, bilateral foot lesions (Grade II bumblefoot), and paralysis died during transport to the veterinary clinic. Postmortem analysis showed urate deposits on the pericardium and gizzard, along with amyloid accumulation in the liver, confirmed by Congo red staining. Histopathology identified eosinophilic hyaline material between hepatocytes and inflammatory infiltrates in the gizzard and heart. Chronic inflammation from bumblefoot and metabolic disturbances from visceral gout were implicated as triggers for amyloidosis, consistent with prior studies linking AA amyloidosis in birds to prolonged inflammation, stress, and poor captive conditions. The liver was the main site of amyloid buildup, suggesting liver failure as a likely cause of death, contrasting with mammals, where the kidneys are usually affected.