Veterinary World最新文献

Background and aim: Proteases are key enzymes that hydrolyze peptide bonds enhancing the utilization of feed protein, improving nutrient efficiency, and reducing the need for costly protein ingredients. Despite their growing use in animal nutrition, comparative studies between fungal and microbial proteases in ruminants remain scarce. This study aimed to evaluate the influence of fungal and microbial proteases (25 U/g each) on the microbial composition of rumen fluid and feces, and on the chemical composition of digestive contents in Kazakh White Head bulls.

Materials and methods: Twenty bulls (14-15 months old; 310-320 kg) fitted with rumen fistulas were divided into three groups: a control group and two treatment groups, each receiving a basal diet supplemented with either fungal or microbial protease. Rumen fluid and fecal samples were analyzed for taxonomic profiles using next-generation sequencing (MiSeq, Illumina) of the 16S ribosomal RNA V3-V4 region. Chemical composition (dry matter [DM], crude protein [CP], crude fat [CF], crude fiber, and ash) was determined according to GOST mass fraction of DM 31640, mass fraction of CP 13496.4, mass fraction of CF 13496.15, mass fraction of crude fiber 31675, and mass fraction of crude ash 26226 standards. Statistical analysis was performed using the Mann-Whitney U-test (p ≤ 0.05).

Results: Microbial protease supplementation increased the abundance of beneficial phyla Bacillota (70.1%) and Bacteroidota (19.5%) in rumen fluid, with a corresponding rise in DM (+6.3%), CF (+9.4%), and CP (+7.9%) relative to control. In feces, Bacillota (70.7%) and Bacteroidota (15.5%) predominated. No opportunistic pathogens (e.g., Pseudomonas and Sutterella) were detected in the microbial protease group, indicating improved microbial balance and intestinal protection. Fungal protease exerted milder effects, with modest increases in nutrient fractions.

Conclusion: Microbial protease was more effective than fungal protease in optimizing rumen microbiota and enhancing nutrient digestibility in bulls. Its use may support environmentally sustainable livestock production by reducing nitrogen excretion and dependence on high-protein feed ingredients. These findings provide a scientific basis for breed-adapted enzymatic feeding strategies in ruminants.

Background and aim: Antimicrobial resistance (AMR) resulting from antibiotic misuse in livestock poses a growing threat to animal and human health. The development of sustainable probiotic alternatives supports the United Nations Sustainable Development Goals (SDGs) for zero hunger (SDG 2), good health and well-being (SDG 3), and responsible consumption and production (SDG 12). This study aimed to isolate, characterize, and perform genomic analysis of lactic acid bacteria (LAB) from swine feces exhibiting antibacterial activity against pathogenic Escherichia coli, to explore their potential as eco-friendly probiotic feed additives.

Materials and methods: Thirty fecal samples were collected from slaughtered crossbred pigs in Thailand. LAB isolates were screened for antibacterial activity against five E. coli pathotypes (Enteroaggregative E. coli, enterohemorrhagic E. coli, enteroinvasive E. coli, enterotoxigenic E. coli, and enteropathogenic E. coli) and assessed for acid and bile tolerance, adhesion capacity, and gastrointestinal survival. Two promising isolates (ATP111 and ATP210) were subjected to whole-genome sequencing and bioinformatics analyses for genes related to antimicrobial production, stress tolerance, virulence, and AMR.

Results: Among 93 initial isolates, Lactiplantibacillus argentoratensis ATP111 and Weissella cibaria ATP210 exhibited broad-spectrum inhibition against all E. coli pathotypes. Both strains survived under pH 2.5 and 1% bile conditions, showing 74.39% and 66.90% survival, respectively, in simulated gastrointestinal conditions. Genomic analyses revealed the presence of genes encoding bacteriocins, polyketide synthases, terpenes, and multiple stress-response proteins, supporting their resilience and antimicrobial functionality. Importantly, both genomes lacked virulence and AMR genes, confirming biosafety for probiotic use.

Conclusion: The integrated phenotypic and genomic evidence positions L. argentoratensis ATP111 and W. cibaria ATP210 as safe, effective, and sustainable probiotic candidates for swine health management. Their application as antibiotic alternatives aligns with SDG 3 (good health and well-being), SDG 12 (responsible consumption and production), and SDG 15 (life on land), contributing to reduced antibiotic dependence and improved livestock sustainability. Future in vivo validation is recommended to confirm efficacy and support global AMR mitigation efforts.

Background and aim: The emergence of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli in food sources poses a growing threat to public health. Poultry eggs may act as vehicles for these resistant bacteria, facilitating their transmission through the food chain. This study aimed to determine the prevalence, antimicrobial resistance (AMR) patterns, and ESBL-encoding genes among E. coli isolates recovered from chicken, duck, and quail eggs sold in Can Tho City, Vietnam.

Materials and methods: A total of 900 eggs (300 each from chicken, duck, and quail) were collected from local markets, retail stores, and supermarkets between June and December 2024. E. coli isolates were identified through biochemical tests and polymerase chain reaction (PCR) targeting the uidA gene. ESBL production was determined using the disk diffusion method, and the presence of bla _CTX-M, bla _TEM, bla _NDM, and bla _SHV genes was confirmed by PCR. Antimicrobial susceptibility was tested against 10 antibiotics representing eight classes following Clinical and Laboratory Standards Institute (2021) guidelines.

Results: Out of 179 pooled samples positive for E. coli, 52 isolates (29.1%) were confirmed as ESBL producers. The highest prevalence was observed in chicken (32.4%) and duck (32.8%) eggs, while quail eggs showed a prevalence of 20%. ESBL-producing isolates most frequently carried bla _CTX-M (65.4%) and bla _TEM (44.2%) genes, whereas bla _NDM was detected in 1.9% of isolates and bla _SHV was absent. All isolates were multidrug-resistant, exhibiting resistance to 4-9 antibiotic classes. High resistance was observed to amoxicillin-clavulanate (69.2%), ceftriaxone (69.2%), tetracycline (75%), and trimethoprim-sulfamethoxazole (61.5%). No E. coli was detected in supermarket eggs, suggesting improved hygiene practices reduce contamination.

Conclusion: The detection of ESBL-producing and multidrug-resistant E. coli on poultry eggshells underscores a significant public health concern. The predominance of bla _CTX-M and bla _TEM genes highlights the risk of resistance gene dissemination through the egg supply chain. Enhanced surveillance, responsible antibiotic use, and strict hygiene control in small-scale poultry production systems are urgently needed to mitigate the spread of AMR under the One Health framework.

Background and aim: Mitigating enteric methane emissions in ruminants remains a global challenge in achieving sustainable livestock production. Although seaweed supplementation has shown promising results, most research has focused on temperate species, leaving tropical species underexplored. This study investigated the nutritional composition, bioactive compounds, and in vitro rumen fermentation characteristics of two tropical seaweeds, brown seaweed (Sargassum binderi) and green seaweed (Kappaphycus striatum), as potential functional feed additives for ruminants.

Materials and methods: The proximate composition, macro- and micro-minerals were determined using Association of Official Analytical Chemists and Inductively Coupled Plasma-Optical Emission Spectrometry methods. In vitro digestibility of dry matter digestibility (DMD) and organic matter digestibility (OMD) was evaluated using the Tilley and Terry two-stage technique. Rumen fermentation characteristics, pH, ammonia (NH₃), and total volatile fatty acids (VFA), were analyzed after 48 h of incubation. Amino acids and fatty acids were profiled using high-performance liquid chromatography and gas chromatography-flame ionization detection, respectively, while bioactive metabolites were identified through liquid chromatography-high-resolution mass spectrometry metabolomics.

Results: Green seaweed exhibited a higher crude protein content (7.52%) and digestibility (DMD = 73.56%; OMD = 72.71%) than brown seaweed (6.84%; 46.38%; 44.99%). VFA production (136.75-151.75 mM) and NH₃ concentrations (22.21-26.78 mM) differed significantly (p < 0.01) between species, while pH remained within the optimal range (7.00-7.21). Both seaweeds contained balanced essential and non-essential amino acid profiles and abundant polyunsaturated fatty acids, notably linoleic, α-linolenic, eicosapentaenoic acid, docosahexaenoic acid, and conjugated linoleic acid. Metabolomic screening identified ~85 bioactive compounds, including lipid-derived metabolites, amino alcohols, vitamins, and osmolytes such as betaine and cholecalciferol, indicating their potential to modulate rumen fermentation and enhance animal resilience.

Conclusion: Both S. binderi and K. striatum demonstrated promising nutritional and bioactive potential as ruminant feed additives. Their compositional diversity suggests species-specific applications - S. binderi as an energy-dense supplement and K. striatum as a functional additive for stress adaptation. However, further in vivo trials are necessary to determine optimal inclusion levels, long-term safety, and methane mitigation efficacy under production conditions.

Background and aim: Acanthamoeba spp. is free-living protozoa capable of causing severe infections, notably Acanthamoeba keratitis, which is difficult to manage due to cyst resistance and the cytotoxicity of current treatments. Plant-derived compounds represent a promising alternative strategy. This study investigated the amoebicidal, anti-adhesive, and cytotoxic properties of Mangifera indica L. (mango) leaf extract against ocularly relevant Acanthamoeba spp.

Materials and methods: Crude ethanolic leaf extract of M. indica was prepared and evaluated against Acanthamoeba polyphaga American Type Culture Collection (ATCC) 30461 and Acanthamoeba castellanii ATCC 50739. Minimum inhibitory concentration (MIC) and minimum parasiticidal concentration were determined for trophozoites and cysts. Morphological changes were analyzed by scanning electron microscopy (SEM). Anti-adhesion assays were conducted using polystyrene surfaces, with a commercial multipurpose contact lens (CL) solution as a control. Cytotoxicity was tested in Vero cells using the 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide assay to establish the minimum cytotoxic concentration.

Results: The extract inhibited trophozoite growth at 2 mg/mL and demonstrated cysticidal activity at 4 mg/mL for A. polyphaga and 32 mg/mL for A. castellanii. SEM revealed disruption of trophozoite morphology, loss of acanthopodia, and surface perforations in cysts. At MIC levels, adhesion was reduced by >70%, and even at 1/8 MIC, inhibition remained above 50%, comparable to a commercial multipurpose solution. Cytotoxicity assessment showed >80% Vero cell viability at 0.125 mg/mL, indicating a favorable therapeutic window.

Conclusion: This is the first report demonstrating amoebicidal and anti-adhesive effects of M. indica L. leaf extract against ocular Acanthamoeba species. The dual trophozoiticidal and anti-adhesive actions, combined with low cytotoxicity, highlight its potential for development as a plant-based therapeutic agent, particularly in ocular formulations or CL disinfectants. Future work should focus on phytochemical isolation, mechanistic studies, and novel delivery systems to enhance efficacy and safety.

Antimicrobial resistance (AMR) in enteric pathogens such as Escherichia coli and Salmonella spp. has emerged as a critical global health challenge affecting both human and animal populations. The widespread use of antibiotics in food-producing animals for therapeutic, prophylactic, and growth-promoting purposes has accelerated the selection and dissemination of resistant bacteria and resistance genes throughout the food chain. Animal-origin foods, including meat, milk, eggs, and fish, serve as important vehicles for the transmission of multidrug-resistant organisms and AMR genes to humans, representing a significant One Health concern. This review provides an overview of the occurrence, molecular mechanisms, and transmission pathways of AMR in E. coli and Salmonella isolated from animal-derived foods. Common resistance determinants include β-lactamase genes (bla_TEM and bla_CTX-M ), tetracycline resistance genes (tetA and tetB), and plasmid-mediated quinolone resistance genes, which facilitate horizontal gene transfer through plasmids, integrons, and transposons. Global surveillance reports from World Health Organization's Global Antimicrobial Resistance Surveillance System, European Food Safety Authority, and World Organization for Animal Health reveal significant regional disparities, with limited monitoring capacity in Central Asia, Africa, and Latin America. Data from Kazakhstan indicate a high prevalence of multidrug-resistant E. coli and Salmonella in poultry, dairy, and cheese products, underscoring the urgent need for harmonized national surveillance and risk management strategies. The review also discusses alternative approaches to reduce antibiotic use in livestock production, including bacteriophage therapy, probiotics, phytogenic feed additives, vaccination, and nanotechnology-based interventions. While these strategies show promising results in laboratory and pilot studies, their practical application remains constrained by regulatory, economic, and field validation challenges. An integrated One Health strategy, combining surveillance, antimicrobial stewardship, and non-antibiotic interventions, is crucial to mitigating the dissemination of AMR along the farm-to-fork continuum. Strengthening laboratory networks, enhancing data sharing, and promoting collaboration among veterinary, environmental, and public health sectors will be crucial to safeguard food safety and global health security.

Background and aim: Getah virus (GETV), a mosquito-borne alphavirus of veterinary importance, has caused periodic outbreaks in domestic animals, especially in Asia. Although several studies have reported evidence of infection in animals, the overall global seroprevalence remains unclear. This study aimed to comprehensively synthesize available evidence on the worldwide seroprevalence of GETV in domestic and wild animals and identify epidemiological patterns across host types, regions, and detection methods.

Materials and methods: A systematic search of PubMed, Scopus, ScienceDirect, and Web of Science was conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines, without temporal or regional restrictions. Eligible studies reporting serological detection of GETV antibodies in animal populations were included. Data were extracted and analyzed using a DerSimonian-Laird random-effects model, with subgroup analyses stratified by country, host category, sampling period, and diagnostic method. Heterogeneity was quantified using I² statistics, and potential publication bias was assessed with funnel plots and Egger's regression test.

Results: Fifteen studies (n = 10,211 animals) met the inclusion criteria. The pooled global seroprevalence of GETV was 33.3% (95% confidence interval: 24.2-43.9; I² = 98.65%, p < 0.001). Malaysia reported the highest seroprevalence (77.2%), followed by China (41.8%) and South Korea (26.4%). Domestic animals (34.0%) exhibited higher exposure than wild species (29.2%), with pigs (43.1%) and cattle (43.2%) recording the highest rates. Studies using virus-neutralization tests yielded higher estimates (47.3%) than those employing enzyme-linked immunosorbent assay (31.4%) or hemagglutination inhibition (7.3%). Meta-regression revealed study location and diagnostic method as significant sources of heterogeneity.

Conclusion: This meta-analysis demonstrates that GETV is endemic among Asian animal populations, particularly domestic livestock, indicating substantial virus circulation across species. The findings underscore the need for enhanced veterinary surveillance, standardized serological testing, and One Health-oriented monitoring frameworks to detect and mitigate GETV transmission risks. The absence of data from Africa, Europe, and the Americas highlights an urgent need for geographically expanded research to better understand the virus's global distribution and zoonotic potential.

Background and aim: Campylobacter jejuni and Campylobacter coli are leading causes of bacterial foodborne gastroenteritis worldwide, with poultry serving as a principal reservoir. The rapid emergence of antimicrobial-resistant (AMR) Campylobacter strains poses a growing public-health challenge, especially in developing countries where therapeutic options are limited. This study investigated the fecal carriage and AMR profiles of zoonotic Campylobacter species (ZCS) isolated from broilers.

Materials and methods: A cross-sectional study was conducted between February and July 2024. A total of 370 broiler fecal samples were collected using systematic random sampling and cultured on Modified Charcoal Cefoperazone Deoxycholate Agar. Phenotypic identification was performed by colony morphology, Gram staining, and biochemical tests. Antimicrobial susceptibility was assessed using the Kirby-Bauer disk diffusion method against nine antibiotics from distinct classes. Multiple antibiotic resistance (MAR) indices were calculated, and Fisher's exact test was applied to determine statistical associations (p < 0.05).

Results: Campylobacter spp. were detected in 20% (74/370) of samples, comprising C. jejuni 6% (22/370) and C. coli 14% (52/370). Nearly all isolates (97.3%) exhibited multidrug resistance (MDR), with MAR indices ranging from 0.2 to 1.0 (mean = 0.8). Thirteen distinct AMR patterns were observed; seven were associated with C. coli and six with C. jejuni. The three most effective antibiotics were gentamicin (GEN) > ciprofloxacin > tetracycline (TET), though C. coli isolates were significantly more resistant to GEN (p = 0.001) and TET (p = 0.018).

Conclusion: The 20% fecal carriage of ZCS in slaughtered broilers and the 97.3% MDR prevalence pose a serious public-health and food-safety threat. Prudent antimicrobial use strengthened farm biosecurity, and active AMR surveillance under a One Health framework are urgently needed to curb the spread of antibiotic-resistant Campylobacter spp. in poultry production systems and to safeguard human health.

Background and aim: Palm kernel meal (PKM), a major by-product of the palm oil industry, is rich in nutrients but poorly utilized in poultry feed due to its high fiber and mannan content. Improving PKM digestibility through microbial bioconversion could reduce dependency on expensive protein sources, such as soybean meal. This study aimed to evaluate a consortium of Bacillus subtilis and Lactobacillus fermentum for its enzymatic activity, probiotic properties, and potential to enhance PKM utilization in poultry diets.

Materials and methods: The research was performed in four stages: (1) measurement of cellulase, mannanase, and protease activities in individual and combined bacterial cultures (seven treatments, five replications); (2) determination of enzyme activities in B. subtilis and L. fermentum (1:1) grown in de Man, Rogosa, and Sharpe broth supplemented with 0%-20% PKM (four treatments, seven replications); (3) in vitro probiotic characterization, including acid and bile tolerance, hydrophobicity, autoaggregation, coaggregation, and pathogen inhibition; and (4) evaluation of enzyme activity in natural media composed of coconut water and shrimp wastewater. Data were analyzed using analysis of variance and Duncan's multiple range tests at p < 0.05.

Results: The 1:1 consortium exhibited the highest enzyme activities; cellulase (13.71 U/mL), mannanase (17.05 U/mL), and protease (9.32 U/mL). The consortium retained high activity in 15% PKM media and demonstrated strong acid tolerance (70.6% survival at pH 2.5), bile salt tolerance (62.84% at 0.3%), and thermal resistance (83.15% at 42°C). It showed 83.75% hydrophobicity, 73.32%-71.64% autoaggregation, and 78.13% coaggregation, along with marked inhibition against Escherichia coli, Salmonella Enteritidis, and Staphylococcus aureus (15.07-17.12 mm inhibition zones). Natural media composed of 70% coconut water + 30% shrimp wastewater supported optimal enzymatic performance.

Conclusion: The B. subtilis-L. fermentum consortium demonstrates potent synergistic enzymatic and probiotic traits, indicating its suitability as a bioenhancer for PKM-based poultry feed. This dual-function probiotic could lower feed costs, improve nutrient digestibility, and support sustainable poultry production. Future work should validate these results through in vivo trials and large-scale fermentation optimization.

Background and aim: Duck circovirus (DuCV) is an immunosuppressive pathogen linked to poor growth, feather abnormalities, and increased susceptibility to co-infections, leading to significant economic losses in duck production. Rapid and large-scale serological screening tools are essential for epidemiological surveillance and biosecurity. This study aimed to develop and validate an indirect enzyme-linked immunosorbent assay (iELISA) based on a recombinant capsid (Cap) protein for sensitive and specific detection of antibodies against DuCV.

Materials and methods: The cap gene from a Thai DuCV genotype I isolate was cloned into the pQE-31 vector and expressed in Escherichia coli M15. The 27 kDa recombinant Cap protein was purified under denaturing conditions, and its antigenicity was confirmed by Western blotting. The iELISA was optimized by checkerboard titration to determine the optimal antigen coating concentration and serum dilution. Diagnostic sensitivity, specificity, cross-reactivity, repeatability, reproducibility, and agreement with Western blotting were assessed using 80 positive, 103 negative, and 189 field serum samples.

Results: The optimized iELISA used 12 μg/well of antigen and a 1:20 serum dilution, producing the highest positive-to-negative optical density ratio. Receiver operating characteristic curve analysis yielded an area under the curve of 0.996, with 97.5% sensitivity and 98.1% specificity. No cross-reactivity was detected with sera positive for duck Tembusu virus, duck viral enteritis virus, or Riemerella anatipestifer. Intra- and inter-assay coefficients of variation were below 6.5% and 9.1%, respectively. Diagnostic agreement with Western blotting across 189 field sera was 91.0%, with a Cohen's kappa of 0.752, indicating substantial concordance.

Conclusion: The developed recombinant Cap-based iELISA provides a reliable, specific, and reproducible tool for large-scale DuCV serosurveillance. Its high diagnostic accuracy and scalability support its application in flock-level monitoring, pre-movement screening, and epidemiological studies, facilitating improved biosecurity and informed disease control strategies within the duck industry.