Vietnam Journal of Agricultural Sciences

The emergence of antibiotic-resistant Escherichia coli, a major causative agent of diarrhea in piglets, presents significant challenges in the swine industry. Bacillus pumilus, widely recognized for its probiotic potential, has been utilized to promote growth performance, enhance immune responses, and inhibit various pathogens in livestock. This study aimed to isolate and characterize B. pumilus with probiotic characteristics from healthy pigs in Hanoi and Hung Yen. A total of three B. pumilus strains were isolated using a routine culture method, PCR, and MALDI-TOF mass spectrometry. The results revealed that all the isolated B. pumilus strains showed non-hemolytic activity on blood agar. The isolates also exhibited high tolerance in acidic (pH 3.0) and bile salt (0.3%) conditions, with survival rates ranging from 77.97% to 95.38% and 82.61% to 93.62%, respectively. Antimicrobial susceptibility tests revealed resistance to tetracycline and erythromycin, while all isolates were also strongly antagonistic to E. coli F4, with inhibition zones ranging from 16-19mm. Overall, the three B. pumilus isolates demonstrated promising probiotic and antibacterial characteristics, highlighting their potential as alternative agents to control E. coli F4 infections in piglets.

Multiple ovulation and embryo transfer (MOET) technologies are efficient strategies for multiplying high genetic merit cows. Gonadotrophin releasing hormone (GnRH) plays a key role in the endocrine control of ovulations in cattle. The objective of this study was to assess the effectiveness of exogenous GnRH injections at the time of artificial insemination (AI) in super-ovulated crossbred temperate dairy cows under tropical environments. Super-ovulations (n = 24) were conducted using 12 genetically sound dairy cows with a standard protocol with two AIs in a 12-hour interval. Cows in the treatment group (TG) (n = 12) received GnRH (100µg) at the first AI and cows in the control group (CG) (n = 12) did not. Embryos were collected by the non-surgical retrograde flushing technique on day 7 post-AI. Collected embryos were classified according to the standard FAO guidelines. Ovulation rate, embryo recovery rate, percentage of transferable embryos, and rate of degenerated oocytes were compared between the two groups. The ovulation rate (P = 0.083) tended to be higher while the median numbers of embryos recovered (P = 0.003), embryo recovery rate (P = 0.008), and percentage of transferable embryos (P = 0.019) were significantly higher in the TG. Further, the number of degenerated oocytes was notably lower in the same group. The results of the study revealed that the administration of GnRH at the time of AI in superovulation protocols significantly improved the embryo production, recovery, and the number of transferable embryos in crossbred cows in tropical environments.

The purpose of this study was to determine the effects of different dietary mineral contents on the growth, survival rate, and biomass increase of the black apple snail, Pila polita, during the nursing phase. Juveniles (0.26 g snail-1) were fed diets with five different mineral supplementation levels: (1) Control (No.Mi); (2) Mineral supplement 3% (Mi3); (3) Mineral supplement 5% (Mi5); (4) Mineral supplement 7% (Mi7); and (5) Mineral supplement 9% (Mi9), with three replicates per treatment. Snails were reared in composite tanks with a density of 300 ind m-2 for 56 days. After 56 days, the snail survival rate in Mi7 (98.4%) was higher (P <0.05) than in No.Mi (95.8%). Snails in Mi7 also obtained the highest height, weight, and yield (23.16mm, 2.58g, and 742 g m-2), which were significantly different from the other treatments (P <0.05). The results also showed that the dietary mineral concentration of 7% generated an acceptable mineral ratio, which could increase snail rearing efficiency.

The giant mottled eel (Anguilla marmorata) is a commercially valuable species that is commonly farmed in Vietnam. The survival rate of glass eels transitioning to the fingerling stage remains a challenge due to high mortality during the nursery phase. A 90-day experiment was conducted in triplicate to evaluate the effects of different stocking densities (200, 225, and 250 fish m-3) in an indoor system at a farm in Da Nang. Additionally, the eels were fed imported formulated feed from Taiwan. Throughout the experiment, water quality parameters were monitored: the water temperature averaged 27.96 ± 1.55°C, pH was 7.85 ± 0.18, DO was 6.29 ± 0.27 mg L-1, NH₃ was 0.22 ± 0.11 mg L-1, and NO₂⁻ was 0.06 ± 0.07 mg L-1. The survival rate was 61.36 ± 10.51% (ranging from 49.91% to 76.99%), and weight gain was 1.47 ± 0.05 g fish-1. Average survival rates (SR%) were recorded at 64.46 ± 9.97%. Overall, these results highlight that, for the nursery rearing of Anguilla marmorata using commercial feed, the optimal stocking density is 200 fish m-³.

Total suspended particles (TSP) from transportation sources pose a growing environmental and public health concern in rapidly developing regions like Vietnam's Mekong Delta. This study investigated TSP emissions and dispersion patterns in Dong Thap province, an area undergoing significant economic transformation. Using the AERMOD air quality model integrated with R-LINE, we simulated TSP dispersion from 43 major roads divided into 88 segments. The model incorporated high-resolution ERA5 meteorological data from 2021-2023, Vietnam-specific emission factors, and detailed traffic data for eight vehicle categories. The results revealed significant spatial and temporal variations in TSP concentrations. In extreme scenarios, TSP levels in urban centers like Cao Lanh city reached up to 1,100 μg m-³ for 1-hour averages and 350 μg m-³ for 24-hour averages, substantially exceeding national standards. Annual average TSP concentrations in urban areas approached or potentially exceeded the 100 μg m-³ national standard, even when considering only transportation sources. The region's flat terrain facilitated long-range TSP transport, with concentrations up to 100 μg m-³ detected beyond provincial borders under extreme scenarios. Atmospheric stability strongly influenced TSP dispersion, with very stable conditions contributing to elevated TSP levels. The study highlights the critical need for targeted air quality management in Dong Thap, particularly in urban areas and along major transportation routes.

Despite significant progress in the field of discrete element modeling (DEM) for agricultural granular materials, currently there is little application of discrete element simulations for agricultural fruit and vegetable sorting and sizing equipment. Thus, this study employed discrete element simulation to enhance the optimization of the working parameters for spherical-shape fruit sizing equipment. The research focused on diameter sizing equipment, investigating the influence of key parameters such as the fruit moving speed and flowrate on sizing efficiency. Fifteen simulation configurations were evaluated using commercial altair EDEM software. The results revealed the optimal combinations of working parameters that maximized yield while minimizing error. This study demonstrates the potential of discrete element simulation in minimizing the need for physical prototypes, accelerating the development process, and reducing time and cost.

The paper presents an analytical solution to investigate the free vibration of a sandwich plate with an auxetic core (negative Poisson’s ratio) and functionally graded face sheets containing porosities (PoFGM), based on the four-variable higher-order shear deformation theory (HSDT-4). The plate is assumed to be supported by Winkler, Pasternak, or Kerr elastic foundations. The governing equations were derived using Hamilton’s principle and were solved analytically using the Navier solution for a rectangular plate with simply supported edges. The results were validated through comparisons with previously published studies, demonstrating the accuracy and reliability of the proposed approach. In addition, the effects of material properties (porosity distribution patterns, porosity volume fraction), geometric parameters of the auxetic core unit cell, the geometric dimensions of the plate, and the elastic foundation on the vibration characteristics were thoroughly analyzed.

In this paper, a novel algorithm is proposed for an Efficient Fault Diagnosis Method (EFDM) for electrical equipment in real time. A combined optical and thermal image processing system is employed to detect thermal anomalies in electrical components in real time. A video camera is initially used to monitor and identify the electrical components, while an infrared camera, aligned with the same viewpoint, is used to capture thermal images of the equipment. The EFDM is then applied to identify and locate faults in electrical components. Numerical results indicate that the proposed algorithm achieves higher accuracy in detecting thermal anomalies compared to existing methods. Evaluation across 300 scenarios shows that the proposed method achieves 97.57% accuracy in localizing abnormal electrical components and 95.30% accuracy in estimating their surface temperatures. These results demonstrate that the proposed thermal anomaly detection algorithm is effective for electrical power monitoring applications.

Spondias lakonensis Pierre is a wild edible fruit used in traditional medicine for the treatment of many diseases. In this study, the nutritional quality and biological activity of S. lakonensis fruits were investigated. The results of the nutritional components analyses were recorded for the vitamin C content (142.80 ± 0.74 mg/100 g) in the pulp, and total ash (2.88 ± 0.07% and 7.25 ± 0.19%), crude lipid (5.80 ± 0.21% and 11.54 ± 0.20%), and total protein (6.70 ± 0.77% and 12.74 ± 1.89%) in the pulp and seeds, respectively. At the suitable conditions for extracting polyphenol compounds (70% acetone at 30°C for 10min with a material/solvent ratio of 1/20 g mL-1), the value of the total polyphenol content (TPC) was 12.32 ± 0.07mg GAE g-1 in the pulp and 24.63 ± 0.07 mg GAE g-1 in the seeds. The results of the DPPH tests indicated that the acetone extracts were good sources of antioxidants with IC50 values of 10.44 ± 0.62 μg mL-1 (pulp) and 29.20 ± 1.76 μg mL-1 (seeds). The extracts also demonstrated strong a-glucosidase inhibitory activities with IC50 values of 0.77 ± 0.02 mg mL-1 in the pulp and 10.24 ± 0.15 mg mL-1 in the seeds. S. lakonensis fruits possess promising nutritional and pharmaceutical potential.

Understanding farmers awareness of applied agri-technologies is critically important for policy development, training, xtension, and trade. This study was conducted by a survey of 248 households in 89 villages of 20 communes in the Central Highlands of Vietnam. Farm households were aware of technologies including plant varieties, animal varieties, drip irrigation, sprinkle irrigation, handy irrigation, greenhouses, semi-processing, fertilizer, and chemicals, etc. Most farmers utilized simple technologies because of a long-time adoption, but other new or high technologies were poorly understood by the households. Based on the results, a gap has been identified, and recommendations have been given to policymakers, training organizations, extension, and traders regarding household capacity building, and providing new technologies of farming materials and requirements. Furthermore, understanding farmers’ perceptions can likely help governance regarding the recent goal of net zero emissions in agriculture and land-use section in Vietnam.

The aim of this paper was to evaluate the associations between the human development index and economic growth, energy use, trade openness, carbon dioxide emissions, and urbanization in Indonesia, Malaysia, the Philippines, Thailand, and Viet Nam between 1991 and 2020 using the fixed effect and random effect models. Due to autocorrelation and heteroscedasticity issues of the fixed effect and random effect models, the feasible generalized least squares model was employed to deal with this problem. The results stated that human development of the five selected Southeast Asian countries may be supported by economic growth and urbanization. However, the relationships between human development and renewable energy consumption, trade openness, and CO2 emissions were insignificant. Finally, policies were recommended to improve the human development index for the region. First, economic growth should be encouraged because it fosters human development. Second, although the urbanization process may improve human development in the region, urbanization should be carefully considered by governments along with creating employment, strengthening education and health quality, and improving living standards for inhabitants. Finally, the nexus between human development and renewable energy consumption, trade openness, and CO2 emissions should be reassessed to carry out appropriate policies for enhancing human development in the region.

The study was conducted to evaluate the impact of student’s perception on e-learning motivation using a case study at the Vietnam National University of Agriculture. The study used an online survey to collect data from 278 students. The Structural Equation Modeling using AMOS package was applied to analyze influencing factors. The results revealed that students' perception of readiness for E-learning (H1: ß = 0.138, P = 0.023), perception of E-learning benefits (H2: ß = 0.315, P = 0.00), and perception of E-learning effectiveness (H3: ß = 0.443, P = 0.00) all have significant positive impacts on their motivation. These findings highlight the importance of enhancing students’ perceptions of E-Learning to foster more effective and engaging E-learning experiences.

Heat stress (HS) is a concerning issue for the health and performance of cattle and is manifested by various behavioral and physiological changes. HS leads to a decrease in dry matter intake, rumen activity, growth performance, and milk yield in animals. Extreme HS for at least three consecutive days increases the risk of death. HS also causes a decline in the ruminal microbiota, pH, and acetate concentration, and an increase in lactate-producing bacteria and the lactate concentration. Reduced feed and water intake lead to a decline in milk production. The milk protein and casein content go down due to insulin resistance and apoptosis of mammary epithelial cells caused by oxidative stress, but urea concentrations become higher. Milk’s metabolomes, glycine, proline, isoleucine, and phosphocreatine have been found to decrease, while citrate, acetone, and β-hydroxybutyric acid concentrations evidently increase. Blood cell count, glucose, protein, and IgG concentrations also fall due to HS. Short estrus, impaired follicular development, poor quality oocytes and spermatozoa, a reduced conception rate, and decreased semen quality have become very common. For all of this, the present study demonstrates the various effects of HS on cattle health, production, and reproduction.