Poultry Science最新文献

Mycoplasma gallisepticum (MG) is a primary avian pathogen that causes chronic respiratory disease, leading to significant economic losses in the poultry industry. This study aimed to investigate the pharmacokinetic/pharmacodynamic (PK/PD) relationship of a novel pleuromutilin derivative, 14-O-[(4-amino-6-hydroxy-pyrimidine-2-yl) thioacetyl] mutilin (APTM), against MG in a chicken infection model to provide a basis for a rational dosage regimen. The in vitro activity of APTM against MG strain S6 was assessed by determining the minimum inhibitory concentration (MIC) and time-kill kinetics. An intratracheal MG infection model was established in chickens. The pharmacokinetic profile was evaluated after single oral administrations of APTM at 5, 15, and 40 mg/kg. The pharmacodynamic efficacy was determined by quantifying the bacterial reduction in the lungs after three consecutive days of oral treatment with doses ranging from 0 to 40 mg/kg. The PK/PD data were integrated and analyzed using an inhibitory sigmoid Emax model. The MIC of APTM against MG S6 was 0.03125 µg/mL, and in vitro time-kill assays demonstrated concentration-dependent bactericidal activity. In chickens, APTM was rapidly absorbed (T_max: 0.25-0.5 h), with both C_max and AUC_0-24h exhibiting excellent dose proportionality (R² > 0.99) over the tested range. In the efficacy study, APTM produced a dose-dependent reduction in lung bacterial load, with a maximum mean reduction of 2.80 log₁₀CFU/mL observed at the 40 mg/kg dose, indicating a bactericidal effect. The PK/PD indices, AUC_0-24h/MIC and C_max/MIC, were both highly correlated with the in vivo antimicrobial effect (R² = 0.9424 and 0.9428, respectively). To achieve a 2-log₁₀CFU/mL reduction in bacterial load, the target AUC_0-24h/MIC value was determined to be 492.75, which corresponds to a calculated daily oral dose of 22 mg/kg. These findings demonstrate the potent efficacy of APTM against MG and provide a quantitative scientific foundation for its therapeutic use in poultry. Specifically, a daily oral dose of 22 mg/kg was identified as the breakpoint for a bactericidal effect (2-log10 reduction), suggesting APTM is a potent candidate for controlling MG infections in poultry.

The laying hen industry is transitioning to cage-free housing, including multi-tiered aviaries, yet research on how aviary configuration influences movement is limited. We examined activity patterns in hens acclimating to two aviary designs. We hypothesized that hen age, time of day (TOD), and aviary design would influence activity. A total of 2,464 Hy-Line Brown hens were placed in two aviary designs (N60 and STEP) at 16 weeks of age (WOA), each replicated across two rooms with four pens per room. The two designs varied in litter accessibility and nest placement. At 18, 28, and 59 WOA, two focal hens per pen (n = 32/WOA) were fitted with triaxial accelerometers. Activity was analyzed for four one-hour periods on the recording day: 1 hour after lights on (morning), 1 hour during noon feeding (noon), 1 hour without management events (afternoon), and 1 hour before lights off (evening). A generalized linear mixed model was used to test the effects of design, age, and TOD, with room and individual hen included as random effects. Horizontal activity showed a significant age × TOD × design interaction (p < 0.0001). Evening consistently had the highest horizontal activity, while morning was typically lowest, except in specific age × design combinations. Vertical activity also showed a significant three-way interaction (p < 0.0001). Vertical activity peaked at 28 WOA across TOD and designs and was lowest at 18 WOA across most TOD in both designs. In summary, horizontal and vertical activity patterns were influenced by the combined effects of age, TOD, and aviary design. The significant three-way interactions indicate that these effects were context-dependent, with movement patterns shaped by the interplay of daily routines, housing design, and age of hens rather than any single factor alone.

Vaccination against Infectious Bronchitis Virus (IBV) stands as a proven, effective approach for significantly curtailing chicken mortality rates in the poultry sector. Recent extensive research has thoroughly explored this area. Our study validates that a specifically engineered Lactobacillus plantarum NC8 strain, capable of co-producing a fusion protein encompassing chicken interleukin-2 (IL-2), IL-17B, and IL-26 (termed NC8-ChIL2/17B/26), amplifies the comprehensive immune response elicited by the IBV vaccine. We assessed its immune-enhancing potential by orally co-administering it with the IBV vaccine to healthy chickens. Following this, we employed ELISA to gauge IBV-specific IgG, IL-2, IL-4, IL-6, and interferon-gamma (IFN-γ) levels in the serum. Likewise, we measured secretory immunoglobulin A (sIgA) levels in the bronchia and intestines. Flow cytometry was utilized to evaluate CD4⁺/8⁺ lymphocyte ratios, while quantitative PCR determined the expression of specific immune-regulating genes. The findings revealed that the NC8-ChIL2/17B/26 group demonstrated elevated levels of pertinent cytokines, antibodies, and CD4⁺/8⁺ T cells relative to the control groups. Moreover, genes such as Toll-like receptor (TLR) 3, TLR7, IL-1β, IL-22, TGF-β, and B-cell lymphoma (BCL)-6 exhibited significantly higher expression in the NC8-ChIL2/17B/26 cohort. Additionally, viral loads in the vaccinated groups were markedly lower compared to those in the control groups, underscoring the better protective efficacy against the potent IBV strain. In essence, our research indicates that oral administration of NC8-ChIL2/17B/26 augments the overall immune response to the IBV vaccine in chickens, positioning it as a secure and efficacious adjuvant for chicken IBV vaccines.

Compared to white-featured broilers, the native Chinese Langshan chickens possess superior meat quality but have a lower growth rate and breast muscle yield. Increasing the breast muscle yield of these breeds while maintaining their high meat quality would greatly enhance their commercial value. Although elevated muscle growth often impairs meat quality, this relationship remains unclear in Langshan chickens. In the present study, 15-week-old Langshan chickens were divided into high (HPB, 14.15 %) and low (LPB, 9.85 %) percentages of breast muscle yield groups after slaughter. Differences in meat quality, myogenic capacity, protein deposition capacity, and metabolic profiles were investigated. Interestingly, the results demonstrated that, compared to the LPB group, the HPB group exhibited improved meat quality with reduced shear force (19.05 N vs 22.63 N) and drip loss (2.50% vs 3.07 %). The HPB group showed a decreased average muscle fiber diameter and an increased muscle fiber density, suggesting increased numbers of muscle fibers. Moreover, immunostaining revealed a higher number of PAX7⁺, MYOD1⁺, and PAX7⁺/MYOD1⁺ satellite cells in the HPB group, accompanied by elevated gene expression of MYF5, MYOD1, and MRF4. Consistently, protein deposition capacity was enhanced as genes and proteins related to protein synthesis were upregulated while genes and proteins related to degradation were downregulated. Untargeted metabolomic profiling identified 253 differential metabolites. Enrichment analysis of up-regulated differential metabolites in the HPB group identified pathways such as unsaturated fatty acid biosynthesis and arachidonic acid metabolism, suggesting a potential function of unsaturated fatty acids in myogenic regulation. We also validated the positive effects of a key differential metabolite, docosapentaenoic acid (DPA), on the myogenic differentiation of SCs by in vitro cell culture experiments. Collectively, these findings provide novel insights that enhancing breast muscle yield did not impair meat quality but instead improved meat tenderness and water-holding capacity, an effect that may be attributable to increased numbers but not sizes of muscle fibers. Therefore, this work establishes a theoretical basis for simultaneously improving breast muscle yield and meat quality in chickens.

Growth curves are key tools for developing and evaluating new feeding programs. This study aimed to evaluate five nonlinear models (Brody, von Bertalanffy, Gompertz, Logistic, and Richards) to describe growth and understand nutrient deposition dynamics in female Japanese quail from 1 to 36 d of age. A total of 225 quail were reared with ad libitum access to feed and water. Every three d, quail were weighed, and one group was fasted for 12 h and slaughtered to determine body protein, fat, and ash contents. Model accuracy was assessed using R², Akaike (AIC), Bayesian (BIC) information criteria, and the Asymptotic Index (AI), ΔAIC, ΔBIC, and by evaluation of biological plausibility. The Gompertz model best fitted body weight and ash deposition, the Logistic model best described crude protein deposition, and the Richards model was selected for fat deposition. Observed and predicted values showed high agreement, with mean bias within ±0.5 g for all traits except fat (-0.73 g). The predicted maximum daily deposition rates were 4.86 g d^-1 for body weight gain, 1.082 g d^-1 for protein, 1.242 g d^-1 for crude fat, and 0.162 g d^-1 for crude ash. Curve overlap indicated the highest growth rate at 16 d, the peak of protein deposition at 18 d, and continuous fat deposition until 35 d. These findings suggest that current feeding programs should be divided into three phases: 1-18, 19-29, and 30-36 d, optimizing nutrient use, growth efficiency, and productive longevity.

This study evaluated the inclusion of spray-dried porcine plasma in the diets of broiler chickens derived from breeder hens of different ages (36 and 56 wk), reared under reused litter and high stocking density conditions (12 broilers/m²). A total of 6,000 one-d-old Cobb®500 broilers were randomly assigned to a completely randomized design in a 2 × 4 factorial arrangement: two breeder ages and four plasma inclusion levels (0%, 0.25%, 0.5%, and 1.0%). Evaluations were conducted across five growth phases: 1-7, 8-14, 15-21, 22-33, and 34-44 d, assessing performance, intestinal morphology, microbiological profile, and economic viability. Breeder age significantly influenced final body weight, weight gain, and feed conversion ratio up to 21 d, as well as villus height up to 44 d and crypt depth at d 7, 21, and 44 d. Effects were also observed on breast and eviscerated carcass weight and yield. Plasma inclusion positively impacted performance up to 14 d, improving weight gain, feed intake, and all histological parameters except goblet cell count, which was affected only up to 21 d. Additionally, plasma influenced breast and carcass traits. A significant interaction between breeder age and plasma inclusion was found for final body weight, weight gain up to 14 d, feed intake across all phases, and mortality rate. Microbiological analysis revealed the presence of Escherichia coli and Salmonella spp. in various biological samples throughout the experiment, with higher incidence at d 21 and 44. Dietary inclusion of porcine plasma improved intestinal morphology and zootechnical performance, with optimal supplementation up to 7 d for broilers from older breeders and up to 21 d for those from younger breeders.

This study evaluated the effects of a multicomponent toxin binder (MTB) and an organic acid blend (OAB) on performance, immunity, oxidative status, liver histology, and jejunal inflammatory/antioxidant gene expression in broilers challenged with aflatoxin B₁ (AFB₁) and Clostridium perfringens. A total of 420 Ross 308 broilers were assigned to seven groups (6 replicates × 10 birds): Control (unchallenged), A (AFB₁), AM (AFB₁ + MTB), AMO (AFB₁ + MTB + OAB), AC (AFB₁+ C. perfringens), ACM (AFB₁ + C. perfringens + MTB), and ACMO (AFB₁ + C. perfringens + MTB+OAB). AFB₁ (500 ppb) was provided throughout days 0-42; C. perfringens (1 × 10⁸ CFU/mL) was administered on days 15-24. AFB₁ alone, and more markedly the AFB₁+C. perfringens co-challenge, reduced body-weight gain and feed efficiency, increased hepatic superoxide dismutase activity and malondialdehyde level, enlarged central-vein diameter, upregulated jejunal NF-κB1, TNF-α, and IL-6, and downregulated hepatic total antioxidant capacity and jejunal NRF2 and SOD1 mRNA expression (P < 0.05). The co-challenge also lowered Newcastle disease antibody titers, reduced phytohemagglutinin-induced toe-web swelling, and increased the heterophil:lymphocyte ratio (P < 0.05). Although MTB attenuated several AFB₁-related impairments, MTB+OAB provided superior protection under co-challenge, increasing hepatic total antioxidant capacity, lowering malondialdehyde, improving liver histoarchitecture (central-vein diameter), and normalizing the expression of immune and antioxidant genes toward control levels, alongside improvements in performance indices (P < 0.05). In conclusion, although co-exposure to AFB₁ and C. perfringens caused greater detriments than AFB₁ alone, adding OAB to MTB improved performance, oxidative, histological, and immunological outcomes, supporting MTB+OAB as a practical strategy for broilers under concurrent mycotoxin-enteric challenge.

In this study, we sought to isolate telocytes (TCs) from embryonic silky fowl skin, characterize their morphological features, and establish a stable in vitro culture system. The isolated and cultured TCs exhibited canonical morphological features, including 2-3 cytoplasmic prolongations (telopodes, Tps) with a moniliform structure. Morphometric analysis using ImageJ (FIJI) software revealed that Tps had an average length of 78.56 ± 10.66 μm, while their podoms and podomers exhibited average thicknesses of 0.20 ± 0.01 μm and 0.06 ± 0.01 μm, respectively. Immunofluorescence staining confirmed the identity of the isolated cells, with positive expression of CD34 and vimentin, consistent with known TCs markers. Transmission electron microscopy (TEM) observations indicated that Tps frequently established homocellular connections. Collectively, the isolated and in vitro-cultured cells exhibited structural and immunophenotypic features characteristic of TCs, confirming their successful isolation from avian embryonic skin. These cells establish a valuable in vitro model for future studies into the physiological functions of avian skin TCs.

Fatty Liver Hemorrhagic Syndrome (FLHS) is a metabolic disorder characterized by hepatic lipid metabolism dysfunction in poultry. This study aimed to investigate the efficacy and underlying mechanism of a solid dispersion of genistein (SDG) in ameliorating FLHS in laying hens. In this study, a total of 60 Lohmann gray laying hens, aged 40-week-old, were randomly divided into five groups including the control group (normal diet), MOD group (high-energy low-protein diet; HELP diet), GEN group (400 mg/kg GEN + HELP diet), SDG group (3200 mg/kg SDG + HELP diet), and physical mixture of GEN group (PMG) (3200 mg/kg PMG + HELP diet). The results demonstrated that all three treatment groups exerted therapeutic effects on FLHS, with SDG exhibiting the superior efficacy. SDG improved the production performance of laying hens, modulated hepatic function, and reduced blood lipid levels. Furthermore, SDG supplementation attenuated intestinal pathological damage and restored intestinal permeability and barrier function. Meanwhile, SDG reshaped gut microbiota structure and metabolite composition, increasing the abundance of Akkermansia, UCG-008, Elusimicrobium, Zag_111, and phosphoglycerides (P < 0.05), and reducing Bifidobacterium and lysophospholipids (P < 0.05). Transcriptomic analysis showed that the pyruvate metabolism pathway was significantly enriched. SDG upregulated the expression of PCK2, PC, and ACAT2 within this pathway, while downregulating the expression of ME1. The underlying mechanism may involve the inhibition of hepatic triglyceride synthesis, the facilitation of free cholesterol conversion into cholesterol esters, and the promotion of oxaloacetate and acetyl-CoA entry into the tricarboxylic acid cycle, thereby suppressing hepatic lipid deposition. In conclusion, our study demonstrated solid dispersion technology enhanced the effect of GEN on alleviating FLHS, and established a foundation for applying SDG to improving poultry liver health.

Optimizing the use of dietary emulsifiers and prebiotics in relation to fat source may enhance nutrient-utilization efficiency in broiler production. This 42-d study evaluated the effects of an emulsifier (lysophospholipid; LPL) and inulin supplementation in diets with two fat sources on growth performance, nutrient digestibility, muscle fatty acid composition, digestive enzyme activity, and intestinal histomorphology. Eight hundred 1-d-old male broiler chickens were assigned to eight treatments in a 2 × 2 × 2 factorial design with two fat sources (soybean oil or beef tallow), two LPL levels (0 or 1 g/kg), and two inulin levels (0 or 1 g/kg). Interactive effects were detected for fat source × inulin on average daily gain (ADG), mortality, and the European Production Index (EPI), with inulin addition to soybean-oil-based diets yielding superior growth and survival rates (P < 0.05). The LPL × inulin interaction increased feed intake and improved gain-to-feed ratio (P < 0.05). The fat source × LPL interaction significantly influenced lipid-metabolism-related traits (P < 0.05); in tallow-based diets, LPL supplementation increased fat digestibility and AMEn, reduced breast fat deposition, and improved the fatty acid profile of thigh muscle by elevating n-3 PUFA and lowering the n-6/n-3 ratio, whereas no significant effects occurred in soybean-oil-based diets. When interaction terms were not significant, LPL increased protease and lipase activities and improved duodenal villus height and surface area, whereas inulin increased protease activity, improved protein digestibility, and enhanced jejunal villus architecture (P < 0.05). In conclusion, LPL is particularly beneficial in tallow-based diets by enhancing lipid digestibility, energy utilization, and the thigh-muscle fatty acid profile, while inulin improves growth performance, especially in soybean-oil-based diets-offering a practical strategy to optimize broiler production.