Evaluation of dietary manipulations to improve growth performance and reduce Salmonella Typhimurium prevalence and shedding in finishing swine

Two disease challenge studies were conducted to evaluate the effect of dietary treatment on growth performance, and level and incidence of fecal Salmonella shedding and tissue colonization of Salmonella in growing-finishing pigs. In the first study, 175 pigs were used in a two-part study. Pigs were fed one of three dietary treatments: corn-soybean meal control (C), C + a polyclonal antibody (PCA), or C + 50% distiller's dried grains with solubles (DDGS). Part I was a 16-wk growth performance study to measure ADG, ADFI, and G:F (n = 135). Part II was a 6-wk disease challenge study (n = 40). Serum haptoglobin (Hp), alpha1-glycoprotein (AGP), IgM and IgG, fecal shedding, and prevalence of Salmonella in tissues at necropsy were measured in Part II. The results indicated that pigs fed diets containing 50% DDGS had decreased ADFI and ADG compared to pigs fed C diets or diets containing a PCA. Growth performance of pigs fed PCA was similar to pigs fed the C diet. The disease challenge model used in this study was unsuccessful in producing an acute salmonellosis infection in finishing pigs inoculated with Salmonella Typhimurium. Therefore, differences in Salmonella infection or shedding due to dietary treatment could not be determined.; In the second experiment, forty finishing pigs (113 +/- 2.1kg initial BW), were used in a disease challenge study to determine the effects of two direct fed microbials (DFM) on the ability of pigs to resist an infection from Salmonella Typhimurium. Pigs were fed one of three dietary treatments: a corn-soybean meal control diet (C), C + a DFM added in the water (PROBIOS), and C + 0.05% DFM included in the feed (BIOPLUS). Ten pigs were not challenged with Salmonella (NC), while the remaining 30 pigs received intranasal inoculation with S. Typhimurium. Qualitative and quantitative fecal shedding, tissue prevalence of Salmonella, and serum Hp, AGP, IgM, and IgG concentrations were measured. The results indicated a successful disease challenge model, but no differences in incidence or severity of the acute salmonellosis infection was apparent among challenged pigs fed PROBIOS or BIOPLUS compared to pigs fed the C diet.