Research Note: Effect of organic acid mixture on growth performance and Salmonella Typhimurium colonization in broiler chickens

Feed additives can be alternatives to antibiotics for routinely encountered pathogens in the poultry production. The objective of this study was to understand effects of organic acid mixture on growth parameters and Salmonella Typhimurium (ST) colonization in broilers. Organic acid mixture is a feed-grade buffered formic acid and sodium formate mixture (Amasil NA). A total of 800 1-day-old Cobb500 males were fed one of the five dietary treatments: a negative control diet without ST challenge (NC), positive control diet with ST challenge (PC), 0.3% organic acid mixture with ST, 0.6% organic acid mixture with ST, and 0.9% organic acid mixture with ST. Treatments were assigned to 20 pens with 40 chicks/pen and 4 replicates of each treatment. Chickens were challenged with 10(7) CFU/mL of nalidixic acid–resistant ST (ST(NAR)) 4-D posthatch. In the grower phase, feed conversion rate was significantly reduced in the 9% organic acid mixture compared with the PC. The body weight and body weight gain (BWG) were not affected either in the starter or grower phases. However, in the finisher phase, the nonchallenged NC had higher BWG than the PC (P < 0.05), whereas there were no differences in BWG among the NC and organic acid mixture fed groups. In addition, there was a significant effect of organic acid mixture on the colonization of cecal ST(NAR). At 9 dpi, cecal ST(NAR) was 3.28 log(10) in the PC that was reduced to 2.65 log(10) at 0.3%, 1.40 log(10) at 0.6%, and 0.84 log(10) in 0.9% organic acid mixture. At 24 dpi, cecal ST(NAR) recovery was 0.81, 0.99, 0.53, and 0.33 log(10) in the PC and 0.3, 0.6, and 0.9% organic acid mixture, respectively. Similarly, at 38 dpi, cecal ST(NAR) was 0.26, 0.11, 0.33, and 0 log(10) in the PC, 0.3, 0.6, and 0.9%, respectively. These results show that organic acid mixture can be one dietary strategy to control ST infection and maintain efficient growth performance.