Background and Aim: African swine fever (ASF) is a notifiable viral disease of pigs and wild boars that causes severe economic losses to the swine industry. The pig industry in Vietnam was recently attacked by the ASF virus (ASFV) for the first time in history. However, we lack information regarding the transmissibility of ASF within indoor production systems communities, such as those in Vietnam. Therefore, we aimed to estimate the basic reproduction number (R0) for ASF during the early stages of transmission between farms in indoor production system communities from local and national data in Vietnam. Materials and Methods: The linear regression model approach for the susceptible infectious method was used in this study to estimate the transmission rate and, consequently, the R0 value. Results: The R0 values between-farm of ASF ranged from 1.41 to 10.8 in different scenarios of infectious period duration, from 15 to 30 days at the national and local levels. Conclusion: These results help to understand the scale and speed of ASF infection in Vietnam and to provide a scientific basis to implement control measures to restrict the spread of ASFV in other locations.

Background: African swine fever (ASF) is a notifiable viral disease of pigs and wild boars that could lead to serious economic losses for the swine industry. Objectives: The aim of this study was to identify risk factors in the early phase of ASF outbreaks in Vietnamese swine herds during the first epidemic year. Methods: The period of interest for this case-control study was February to July 2019. A questionnaire was administered in northern Vietnam where all early cases of ASF were reported. Producers of herds with reported cases were asked to provide information starting from the day of onset of clinical signs as well as 30 days prior to that day. The period of interest for controls was within the 6 months of the first outbreak in Vietnam (February 2019). Questionnaires included 55 questions; responses were received from 67 cases and 115 controls. Logistic regression analysis was used to identify factors associated with ASF status. Results: Thirty-seven variables of interest (among a total of 55 variables) were associated with ASF status in univariate analysis (p < 0.05). These 37 variables were assessed for inclusion in the multivariate analysis by backward stepwise selection. Six variables remained significant as ASF risk factors in the final model: distance to farm within 500 m, distance of irrigation systems within 200 m, total number of pigs (<= 500), absence of dressing rooms for workers/visitors before entering the farm, poor hygienic practices for people within the farm, and poor hygienic practices at pig loading/unloading locations. Conclusions: These results may help in understanding the epidemiology of ASF in Vietnam and provide a scientific basis for optimization of current interventions and development of new tools and strategies to reduce transmission of ASF.

This study aimed to evaluate a dietary phytogenic preparation (PT) comprising Ginkgo biloba L. leaves and mangosteen extract in broilers challenged with pathogenic Eimeria tenella. One-day-old Arbor Acres broilers (n = 600) were randomly assigned to a treatment group (six replicate floor pens/treatment, 20 chicks/replicate): non-challenged and control diet-fed negative control group (NC); E. tenella challenged and control diet-fed positive control group (PC); and PC + PT (50, 100, or 200 mg PT/kg of diet). On day 14, all groups except NC were gavaged with 1.0 × 10⁴ oocysts of E. tenella. The Eimeria challenge impaired (P < 0.05) body weight, which was mitigated by dietary PT on days 21 and 28. Furthermore, E. tenella challenge increased cecal lesion scores; however, dietary PT preparations reduced (P < 0.001) these lesions. Moreover, Eimeria challenge impaired ileal morphology; however, dietary PT alleviated these changes. All E. tenella-challenged broilers exhibited lower total short-chain fatty acid content in their cecal digesta and partially lowered (P = 0.055) ileal digestibility of crude fat being the latter linearly improved by dietary PT preparations (P < 0.05). Nitric oxide concentrations in the serum and cecal mucosa were elevated after Eimeria challenge; however, they were relieved by dietary PT in a concentration-dependent manner. Serum total cholesterol and high-density lipoprotein cholesterol concentrations in the Eimeria-challenged groups were lower than those in the NC group. Eimeria challenge also decreased catalase activity in the liver and superoxide dismutase activity in the cecal mucosa, but increased glutathione peroxidase activity in the cecal mucosa compared with that in the NC group. Increasing dietary PT concentrations increased serum (linear effect, P = 0.031) and liver (linear effect, P = 0.034) glutathione peroxidase levels and superoxide peroxidase activity in the cecal mucosa (quadratic effect, P = 0.015). Collectively, dietary PT shows promising potential as a nutritional solution to reduce avian coccidiosis via the modulation of innate and antioxidant markers and the alleviation of Eimeria-specific cecal lesions.

The study was conducted to evaluate the influence of Saccharomyces boulardii (SB) supplementation on growth performance, meat quality, cecal volatile fatty acid (VFA) profile, immune parameters, and serum biochemistry in broiler chickens fed diets with varying nutrient densities. A total of 420 day-old male broiler chicks (Ross 308) were randomly allocated to 28 floor pens. A 2 × 2 factorial design was employed, with two factors: SB supplementation (none or 2.0 × 10¹⁰ CFU/ton), and optimal (OPT) and deficient nutrient density (DEF). The OPT diet significantly improved body weight gain and feed intake across all phases and enhanced the feed conversion ratio during the finisher and overall periods compared to the DEF diet (p < 0.05). However, SB supplementation decreased body weight gain during the starter and overall periods (p < 0.05). Serum levels of glutamic-oxaloacetic transaminase, glutamic-pyruvic transaminase, and triglyceride were elevated in chickens fed the OPT diet (p < 0.05). While SB supplementation did not affect meat quality or cecal VFA profiles, it interacted with nutrient density to influence alpha-1-acid glycoprotein and interferon-gamma concentrations in serum samples (p < 0.05). In conclusion, dietary supplementation with S. boulardii did not affect growth performance in broiler chickens regardless of nutrient density levels. However, it interacted with nutrient density to modulate the innate immune markers suggesting the immune-modulating role of S. boulardii in chickens.