Veterinary World最新文献

Background and aim: Clostridium perfringens is a major enteric pathogen of goats, capable of producing multiple toxins and harboring diverse antimicrobial resistance (AMR) determinants. The coexistence of toxin diversity and AMR complicates disease control and poses risks to animal health and antimicrobial stewardship. This study aimed to characterize toxin genotypes, phenotypic AMR patterns, and associated resistance genes in C. perfringens isolates obtained from healthy, diseased, and deceased goats in Jiangsu Province, China.

Materials and methods: A total of 404 samples were collected from goats between April 2021 and April 2022, including feces from healthy animals, rumen contents from slaughtered goats, and intestinal contents and visceral tissues from diseased or deceased goats. Isolation and identification of C. perfringens were performed using anaerobic culture and 16S rRNA gene sequencing. Toxin genotyping targeting major toxin genes was conducted by polymerase chain reaction (PCR). Antimicrobial susceptibility was assessed using the Kirby-Bauer disk diffusion method, and resistance genes were detected by PCR. Hierarchical clustering was used to explore relationships between toxinotypes and AMR gene profiles.

Results: Ninety-four C. perfringens isolates were recovered (23.3%). Toxinotype A predominated overall (61.7%) and was dominant among healthy goats, whereas toxinotypes D (52.9%), C (14.7%), and F (14.7%) were more frequently detected in diseased or deceased animals. High phenotypic resistance was observed to aminoglycosides, including kanamycin (72.3%), neomycin (66.0%), and gentamicin (58.5%), as well as trimethoprim-sulfamethoxazole (61.7%). All isolates remained susceptible to vancomycin, with low resistance to β-lactams. Resistance genes associated with aminoglycosides, sulfonamides, tetracyclines, quinolones, and lincosamides were widely distributed. Notably, the quinolone resistance gene qnrS and tetracycline resistance genes tetA(P) and tetB(P) were significantly more prevalent in isolates from diseased goats, particularly toxinotype D.

Conclusion: Goat-associated C. perfringens in Jiangsu Province exhibits substantial toxin diversity and a high burden of AMR, with distinct differences between healthy and diseased animals. These findings underscore the need for continuous molecular surveillance, rational antimicrobial use, and integrated control strategies to mitigate risks to goat health and productivity within a One Health framework.

Background and aim: Heat stress (HS) substantially impairs dairy goat productivity in Mediterranean climates by disrupting metabolic, endocrine, and cellular homeostasis. High-yielding Saanen goats are particularly vulnerable because of elevated metabolic heat production, yet age-specific physiological responses to prolonged natural HS remain unclear. This study aimed to characterize age-dependent adaptations to progressive summer HS by evaluating changes in triiodothyronine (T3), thyroxine (T4), cortisol (CORT), and heat shock protein 70 (HSP70), and their relationship to daily average milk yield (DAMY). We hypothesized that increasing temperature-humidity index (THI) would suppress T3 and T4, moderately elevate CORT, and stimulate HSP70 expression, particularly in young goats.

Materials and methods: Thirty clinically healthy, lactating Saanen does were grouped into young, middle-aged, and old age groups (n = 10 per group). The study was conducted from May to August under natural Mediterranean field conditions. Ambient temperature, relative humidity, and THI were recorded daily. DAMY was measured automatically using a radio-frequency identification-linked milking system. Blood samples were collected twice monthly to quantify serum T3, T4, CORT, and HSP70 using commercial enzyme-linked immunosorbent assay kits. A repeated-measures general linear model evaluated the effects of age, month, and their interaction; significance was set at p < 0.05.

Results: THI increased from "no HS" in May to "severe HS" in July and August, confirming sustained heat-load. DAMY declined from 2.59 ± 0.43 kg in May to 1.88 ± 0.40 kg in August. T4 decreased significantly in young and middle-aged goats, with the sharpest decline in middle-aged goats (92.96 to 61.82 nmol/L; p < 0.01). T3 also decreased significantly in young and middle-aged groups (p < 0.01), whereas older goats showed modest, nonsignificant reductions. CORT showed a mild, nonsignificant upward trend. HSP70 increased across all groups, with a significant rise in young goats (13.32 to 17.85 ng/mL; p < 0.05). T4 showed a strong positive correlation with DAMY (r = 0.78, p = 0.0027), whereas CORT showed a moderate negative correlation with DAMY (r = -0.58, p = 0.047).

Conclusion: Lactating Saanen goats exhibit age-dependent dual adaptations to summer HS: endocrine suppression of thyroid activity, stronger in middle-aged goats, and cellular upregulation of HSP70, most evident in young goats. Monitoring T3, T4, CORT, HSP70, and DAMY can help identify thermally vulnerable life-stage groups and guide targeted cooling, nutritional, and breeding interventions in heat-stressed dairy systems.

Background and aim: The global ban on antibiotic growth promoters in poultry production has accelerated the search for safe and effective natural alternatives. Polysaccharides derived from traditional Chinese medicinal plants have shown promise due to their antioxidant and immunomodulatory properties. This study evaluated the efficacy of dietary Scutellaria baicalensis polysaccharide (SBP) as an alternative to in-feed antibiotics by assessing its impact on growth performance, antioxidant status, digestive function, intestinal morphology, and mucosal immunity in broiler chickens.

Materials and methods: A total of 420 one-day-old Arbor Acre broilers were randomly assigned to five dietary treatments for 42 days, with six replicates per treatment. The treatments included an antibiotic-free basal diet (control), a basal diet supplemented with colistin sulfate and virginiamycin (antibiotics), and the basal diet supplemented with SBP at 100 mg/kg (SBP-L), 200 mg/kg (SBP-M), or 400 mg/kg (SBP-H). Growth performance parameters were recorded, and on days 21 and 42, serum and intestinal antioxidant indices, digestive enzyme activities, intestinal morphology, secretory immunoglobulin A (sIgA) levels, and the expression of immune-related genes (C-C motif chemokine ligand 28 [CCL28], A proliferation-inducing ligand (tumor necrosis factor ligand superfamily member 13) [APRIL]) and toll-like receptor 4 protein were evaluated.

Results: Dietary SBP supplementation significantly improved average daily gain (ADG) and feed conversion ratio during the starter phase without affecting feed intake or mortality (p < 0.05). Over the entire 42-day period, broilers fed 400 mg/kg SBP showed a 3.4% higher ADG than those receiving antibiotics (p < 0.05). SBP boosted systemic and intestinal antioxidant capacity by increasing glutathione peroxidase, glutathione reductase, Superoxide dismutase, and total antioxidant capacity activities while lowering malondialdehyde levels (p < 0.05). Additionally, SBP increased digestive enzyme activities, improved villus height-to-crypt depth ratios, and raised sIgA concentrations in the duodenum and jejunum. The upregulation of TLR4 protein and the immune-related genes CCL28 and APRIL indicated enhanced intestinal mucosal immunity, especially in the SBP-M and SBP-H groups.

Conclusion: Dietary supplementation with S. baicalensis polysaccharide, especially at 200-400 mg/kg, effectively improves growth performance, antioxidant defense, and intestinal health in broilers, demonstrating its strong potential as a practical and sustainable alternative to antibiotic growth promoters in poultry production.

Background and aim: Five-aminolevulinic acid (5-ALA), a precursor in heme biosynthesis, has gained attention as a functional feed additive due to its reported benefits on metabolism, redox balance, and immunity. Although supplementation in sows and broilers has demonstrated favorable physiological outcomes, its effects on the gut microbiota and immune-oxidative profiles of weanling piglets remain unclear. This study aimed to evaluate whether 5-ALA supplementation modifies fecal microbiota composition and influences oxidative stress and immune parameters in piglets during the post-weaning period.

Materials and methods: Twelve 28-day-old piglets were randomly allocated to a control or 5-ALA group (20 mg/kg feed) for 56 days. Body weight (BW), fecal samples, and blood samples were collected at 28, 56, and 84 days of age. Fecal microbiota was characterized by 16S rRNA sequencing (QIIME2). Oxidative stress and inflammatory markers in leukocytes (superoxide radical, hypochlorite ion) were quantified using a dual chemiluminescence/fluorescence system. Plasma malondialdehyde (MDA) and immunoglobulin G (IgG) were measured to assess systemic oxidative damage and humoral immunity. Statistical analyses included Permutational Multivariate Analysis of Variance, LEfSe, and Spearman correlations.

Results: BW did not differ significantly between groups, although the 5-ALA group tended to be heavier at 56 days. β-diversity differed significantly between groups at 56 and 84 days. Six and eight bacterial genera were differentially abundant at 56 and 84 days, respectively; 5-ALA supplementation enriched short-chain fatty acids-associated genera such as Coprococcus, Prevotellaceae UCG-003, and Phascolarctobacterium. At 84 days, the 5-ALA group showed markedly lower leukocyte superoxide levels (~3.5-fold reduction; p < 0.05) and a tendency toward lower hypochlorite ion production. Plasma IgG concentration was approximately 1.5-fold higher in the 5-ALA group (p < 0.05). Multiple bacterial genera exhibited significant correlations with oxidative and immune markers.

Conclusion: Dietary supplementation with 5-ALA altered the fecal microbiota and improved oxidative and immune status in weanling piglets, suggesting functional modulation of the gut-immune axis. Although exploratory and based on a small cohort, the findings warrant further controlled studies to validate dose-response effects and elucidate mechanistic pathways.

Background and aim: Despite strong adaptive traits, the reproductive efficiency of Bali cattle (Bos javanicus) remains suboptimal, with low conception rates following artificial insemination (AI). Cervical mucus (CM) is a critical factor in sperm transport and fertilization; however, its molecular basis in relation to fertility has not been elucidated in this indigenous breed. This study aimed to characterize the proteomic profile of CM in Bali heifers and to identify protein biomarkers associated with fertility-related mucus quality.

Materials and methods: The study was conducted between February and August 2024 in South Sulawesi, Indonesia. Forty clinically healthy Bali heifers (2-3 years old) were sampled during natural oestrus and divided into good CM (GCM; n = 20) and poor CM (PCM; n = 20) groups using a validated five-parameter biophysical scoring system. CM proteins were extracted and analyzed using one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by liquid chromatography-tandem mass spectrometry. High-confidence protein identification was achieved at <1% false discovery rate, and differential abundance was evaluated using Benjamini-Hochberg correction (p < 0.05). Functional enrichment, correlation analysis with mucus traits, and receiver-operating-characteristic (ROC) analyses with cross-validation were performed.

Results: Significant differences (p < 0.05) were observed between GCM and PCM groups for appearance, viscosity, spinnbarkeit, and ferning pattern, while pH did not differ. A total of 52 proteins were identified after quality control, of which 13 showed significant differential abundance. GCM was characterized by higher levels of NT5E, lactoferrin, SCGB1D, and lactotransferrin, whereas PCM showed enrichment of complement factor I (CFI), haptoglobin (HP), MUC5AC, FAIM2, TIMP2, PEBP4, SAA3, GRP, and IGL. Functional enrichment analysis indicated anti-inflammatory and epithelial-protective pathways in GCM, in contrast to complement activation, proteolysis, and oxidative remodeling in PCM. ROC analysis demonstrated excellent discriminative performance for NT5E (GCM) and CFI and haptoglobin (PCM), each achieving an area under the curve of 1.00 in this cohort.

Conclusion: This study offers the first proteomic evidence connecting CM composition to fertility-related traits in Bali heifers. NT5E, CFI, and HP stand out as promising biomarkers for fertility screening, providing a molecular framework to improve AI efficiency and selection strategies in indigenous cattle.

Background and aim: Rotavirus A (RVA) is an enteric pathogen affecting both humans and animals, known for its zoonotic potential. Feline RVA (FeRVA) infections are increasingly reported worldwide; however, data remain limited in Thailand. This study aimed to determine the prevalence, genotype distribution, and whole-genome features of FeRVA found in domestic cats in Thailand, as well as to assess the potential for cross-species transmission.

Materials and methods: A cross-sectional survey was conducted from January 2022 to December 2023 in Bangkok and nearby provinces. Rectal swab samples (n = 636) were collected from both symptomatic and asymptomatic cats and screened for RVA using reverse-transcription polymerase chain reaction (RT-PCR) targeting the nonstructural protein 5 (NSP5) gene. Samples positive for FeRVA were subjected to whole-genome sequencing (WGS) using Oxford Nanopore technology. Genotypes were assigned based on all 11 gene segments, and phylogenetic analyses were performed using the neighbor-joining method to compare Thai strains with global RVA reference strains.

Results: The FeRVA positivity rate was 1.41% (9/636). Three FeRVA-positive samples were successfully sequenced. Whole-genome analysis identified one strain as genotype G3P[9] and two strains as genotype G6P[9]. The G6P[9] strains showed the genetic constellation G6-P[9]-I2-R2-C2-M2-A3-N2-T3-E3-H3, identical to feline and human RVA G6P[9] strains previously reported in Japan. The G3P[9] strain displayed high nucleotide identity with Thai and East Asian human RVAs. Most FeRVA-positive cats were asymptomatic, and no significant association was found between infection status and age, season, or clinical signs. Analysis of the viral protein 7 antigenic regions revealed conserved amino acids, apart from a single substitution (S90P) in G6P[9].

Conclusion: This study reports the first detection of the novel FeRVA genotype G6P[9] in Thailand and provides comprehensive genomic evidence of FeRVA diversity in domestic cats. The close genetic relationship between Thai-FeRVA strains and human RVA strains highlights the potential for interspecies transmission. Enhanced surveillance and One Health-based monitoring are recommended to improve early detection and prevent zoonotic spread.

Background and aim: Food-producing animals are recognized reservoirs of antimicrobial-resistant bacteria with zoonotic potential. Third-generation cephalosporin-resistant (3GC-R) Escherichia coli is of particular public health concern due to its association with extended-spectrum β-lactamase (ESBL) and plasmid-mediated AmpC enzymes. This study aimed to determine the prevalence, resistance mechanisms, transferability of resistance genes, efflux pump contribution, and genetic relatedness of 3GC-R E. coli isolated from farm animals and workers on a small-scale farm in lower northern Thailand.

Materials and methods: A total of 265 fecal samples were collected from laying hens (n = 210), cattle (n = 33), swine (n = 19), and farm workers (n = 3). Isolation of 3GC-R E. coli was performed using cefotaxime-supplemented selective media. Antimicrobial susceptibility was determined by disk diffusion and minimum inhibitory concentration (MIC) assays. The presence of bla _CTX-M and bla _CMY-2 genes was identified by polymerase chain reaction and sequencing. Conjugation assays and plasmid replicon typing assessed gene transferability. Efflux pump involvement in ceftazidime resistance was evaluated using phenylalanine-arginine β-naphthylamide. Genetic relatedness was analyzed by pulsed-field gel electrophoresis.

Results: Overall, 15.8% of samples yielded 3GC-R E. coli, with the highest prevalence observed in swine (47.4%), followed by cattle (27.3%) and laying hens (10.5%). Multidrug resistance was detected in 57.1% of isolates. The majority carried bla _CTX-M alone (69.0%) or in combination with bla _CMY-2 (21.4%), and both genes were transferable via IncF and IncI1-I plasmids. A ≥4-fold reduction in ceftazidime MICs in the presence of an efflux pump inhibitor was observed in 38.7% of isolates. While genetically identical strains were detected among different animal species, no clonal transmission between animals and workers was identified.

Conclusion: Small-scale farms in Thailand harbor 3GC-R E. coli with transferable resistance determinants and multiple resistance mechanisms, underscoring their role in antimicrobial resistance dissemination. These findings highlight the need for strengthened biosecurity, antimicrobial stewardship, and integrated One Health surveillance in rural farming systems.

Background and aim: Eimeria tenella is the most pathogenic species affecting chickens and a leading cause of economic loss due to coccidiosis. While live vaccines using virulent or attenuated strains are effective, they can still cause intestinal damage and reduce weight gain. Autophagy, a crucial host cell response during intracellular parasitic infections, shows variations in induction between virulent and precocious E. tenella strains that are not yet well understood. This study compares how host cell autophagy is triggered by the virulent E. tenella Shanxi strain (Tsx) and precocious Tsx (PTsx) strains, both in vitro and live animal experiments.

Materials and methods: Primary chick embryo cecal epithelial cells and specific pathogen-free chickens were infected with either low or high doses of Tsx or PTsx. Infection rates were determined through hematoxylin and eosin (H&E) staining. Autophagy levels were assessed by quantifying Beclin-1 mRNA expression via reverse transcription quantitative real-time polymerase chain reaction, evaluating LC3II puncta accumulation through immunofluorescence (IF), and calculating LC3II/I ratios using Western blot. In vitro experiments were carried out from 4 to 120 h post-infection, whereas in vivo evaluations took place on day 5 after inoculation.

Results: In vitro, infection rates did not differ significantly between Tsx and PTsx groups during early stages (4-72 h), but Tsx showed significantly higher infection rates at 120 h. Both strains induced autophagy in a dose-dependent manner, as evidenced by increased Beclin-1 mRNA expression, LC3II puncta, and LC3II/I ratios compared with controls. These autophagy markers were consistently higher in Tsx-infected cells than in PTsx-infected cells at equivalent doses. In vivo findings mirrored in vitro trends, with stronger autophagy activation observed in Tsx-infected chickens, particularly at high doses. Autophagy activation was markedly amplified in vivo compared with in vitro, indicating the influence of the intestinal microenvironment.

Conclusion: The highly virulent E. tenella strain Tsx causes intense and prolonged autophagy in host cells, while the less aggressive PTsx strain triggers a milder autophagic response. The level of autophagy activation is directly related to the parasite's virulence and infection dose. These results show that excessive autophagy plays a significant role in intestinal damage during E. tenella infection and highlight that reducing host autophagy activation is crucial for developing more effective live attenuated coccidiosis vaccines.

Background and aim: Propranolol is a widely used non-selective beta-adrenergic blocker in human medicine, with well-characterized pharmacokinetics (PK) in humans but virtually no data available for pigs, a species of growing biomedical relevance. Furthermore, no validated bioanalytical methods exist for propranolol or its primary metabolite, 4-hydroxy-propranolol, in porcine matrices. This study aimed to develop and validate a rapid, sensitive, and reliable liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the simultaneous quantification of propranolol and 4-hydroxypropranolol in pig plasma and dried blood spots (DBS), and to apply it in a preliminary PK investigation in pigs.

Materials and methods: Sample preparation involved simple protein precipitation (plasma) or solvent extraction (DBS) using acetonitrile-water mixtures, followed by chromatographic separation on a Bridged ethyl hybrid C18 column (50 × 2.1 mm, 1.7 μm; 4-min run). Detection was performed in Multiple reaction monitoring mode with propranolol-d7 as the internal standard. Validation followed EMA ICH M10 guidelines, assessing linearity, accuracy, precision, matrix effects, recovery, and stability. The method was then applied to plasma samples from five juvenile female pigs receiving oral propranolol (3 mg/kg, q8 h).

Results: The method demonstrated excellent linearity (r² > 0.99) and acceptable accuracy and precision (±15%) across 2-500 ng/mL (propranolol) and 1-400 ng/mL (4-hydroxypropranolol). Recoveries ranged from 83% to 116% (plasma) and 81%-113% (DBS), with no matrix interference or carry-over. In vivo PK data revealed rapid absorption (Tmax 1.14 ± 0.63 h), moderate elimination (t½ 2.19 ± 0.86 h), and a mean Cmax of 112.02 ± 81.87 ng/mL. Notably, 4-hydroxypropranolol was undetectable in all plasma samples, suggesting species-specific metabolic differences.

Conclusion: This study reports the first validated LC-MS/MS assay for propranolol and 4-hydroxypropranolol in pigs and demonstrates its successful application in a PK study. The method's simplicity, short runtime, and compatibility with DBS microsampling make it ideal for preclinical and veterinary research, minimizing animal stress and sampling volume. Absence of 4-hydroxypropranolol highlights interspecies metabolic variability and warrants further investigation into propranolol biotransformation pathways in swine and other translational models.