British Poultry Science最新文献

1. Chicken ghrelin (GH) plays an important role in regulating growth hormone secretion, immunity and gastrointestinal motility. This study utilised haematoxylin-eosin staining, quantitative reverse transcription PCR and western blotting to examine the effects of high-level ghrelin on the proliferation of small intestinal epithelial cells, intestinal nutrient transport and the mucosal immune barrier in chicks.2. Eighty, 17-d-old layer type chicks were randomly divided into two groups: control (C treated with sterile phosphate buffer) and the ghrelin-treated group (GH; intraperitoneally injected with 0.5 nM GH per 100 g body weight). At 1, 3 and 5 d post-injection, six chicks from each group were randomly selected for sampling of the duodenum and ileum.3. Administering GH reduced the expression of proliferating cell nuclear antigen protein in the duodenum and leucine-rich repeat-containing G protein-coupled receptor 5 mRNA in both the duodenum and ileum. In addition, GH affected villus height and ratio of villus height to crypt (H/C) depth in these sections and fatty acid binding protein 6 expression in the ileum. The relative mRNA levels of oligopeptide transporter 1, solute carrier family 3 member 1, solute carrier family 1 member 1 and solute carrier family 5 member 1 were decreased by GH.4. Birds treated with GH had a decrease in duodenal intraepithelial lymphocytes, Paneth cells and ileal goblet cells. There was a reduction in mucin 2 mRNA in goblet cells and lysozyme C and phospholipaseA2 mRNA in Paneth cells. Additionally, the relative mRNA levels of avian β-defensin 1 (AvBD1), AvBD6 and AvBD7 in the duodenum and ileum decreased with GH administration.5. The GH inhibited proliferation of chicken duodenal epithelial cells and decreased surface area available for intestinal villus absorption. This affected the transport of intestinal amino acids, glucose and bile acids and impaired the function of the mucosal immune barrier in both the duodenum and ileum.

1. This study employed an automated estimation method for quantitatively assessing valuable meat parts in broiler chickens. This involved the segmentation of computed tomography (CT) images through elastic registration, utilising feature and model selection.2. Sixty Tetra HB colour broiler chickens (30 males and 30 females) were randomly selected and examined by CT at 10 weeks of age (live weight: 2560 ± 400 g). The animals were slaughtered, and their breast and thigh muscles were dissected and weighed (thigh and breast weights were 90 ± 19 g and 337 ± 58 g). Multi-atlas registration was used for segmentation, followed by feature extraction (256 features/individual) from the CT images.3. Four different regression analysis techniques (linear, PLS, lasso and ridge) with and without feature selection were applied to the collected data with k-fold cross-validation for estimating the thigh and breast muscle weights. The feature selection produced significantly better results in all cases.4. Among the analysis techniques, lasso and ridge regression performed the best for both muscle groups (thigh and breast muscles). These were as follows: lasso for breast: r² = 0.993, RMSE = 4.87 g; ridge for breast: r² = 0.995, RMSE = 4.03 g; lasso for thigh: r² = 0.976, RMSE = 2.94 g; and ridge for thigh: r² = 0.965, RMSE = 3.53 g.5. The results demonstrated the effectiveness of the automated method, initially tested on rabbits, in accurately estimating valuable meat parts of broiler chickens. The robust performance of the selected regression models underscores the potential for widespread application in poultry production, offering a reliable and efficient means of quantitative assessment.

1. This study assessed the effects of in ovo injection of Marek's disease vaccine (MDV), alone (control) or combined with 1.25 μg of 25-hydroxycholecalciferol (25(OH)D₃), 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)D₃ 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)D₃ 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)D₃ 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)D₃ group demonstrated greater strength on d 1 and 7 but not at later times.4. In conclusion, this study showed that combining 25(OH)D₃ with MDV does not impact hatchability or overall performance but does enhance early bone strength and growth in broiler chicks.

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 LEAP2 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 ghrelin and hypothalamus GHSR 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 (Alectoris chukar) 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. 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. The nutritional potential of Faba bean (Vicia faba 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 (p < 0.01), with an interaction between autoclaving and phytase on AID of P (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 (p < 0.01).

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 meq 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 meq 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.