Feed additives have been suggested to improve animal growth performance through modulating the gut microbiota. The hypothesis of this study was that the combination of two organic acids would exert synergistic effects on the growth performance and gut microbiota of weaning pigs. To test this hypothesis, we followed 398 weaning pigs from two university experiment stations (University of Illinois at Urbana-Champaign (UIUC) and University of Arkansas (UA)) to determine the effects of increasing levels (0%, 0.035%, 0.070%, and 0.105%) of sodium butyrate combined with 0.5% benzoic acid on the growth performance of nursery pigs. At the UA, an additional negative control diet was included and the gut microbiota analysis was carried out. At both universities, increasing levels of sodium butyrate in a diet containing 0.5% benzoic acid improved growth performance, which reached a plateau in the pigs fed 0.035% (SBA0.035) or 0.070% (SBA0.070) butyrate. Gut microbiota analysis revealed that pigs fed the SBA0.035 diet had more diverse microbiota and contained more potentially beneficial bacteria such as Oscillospira, Blautia, and Turicibacter and reduced levels of Veillonella and Sarcina. Results of the present study indicated that the inclusion of sodium butyrate at moderate levels in a diet containing 0.5% benzoic acid improved growth performance of weaning pigs and established potential health benefits on gut microbiota.

African swine fever virus is one of the most highly contagious and lethal viruses for the global swine industry. Strengthening biosecurity is the only effective measure for preventing the spread of this viral disease. The virus can be transmitted through contaminated feedstuffs and, therefore, research has been conducted to explore corresponding mitigating measures. The purpose of the current study was to test a combination of pure benzoic acid and a blend of nature identical flavorings for their ability to reduce African swine fever viral survival in feed. This virus was inoculated to feed with or without the supplementation of the test compounds, and the viral presence and load were measured by a hemadsorption test and quantitative real time polymerase chain reaction. The main finding was that the combination of pure benzoic acid and nature identical flavorings could expedite the reduction in both viral load and survival in a swine feed. Therefore, this solution could be adopted as a preventive measure for mitigating the risk of contaminated feed by African swine fever virus.