Effect of different concentrations of acetic, citric, and propionic acid dipping solutions on bacterial contamination of raw chicken skin.

Bacterial contamination of raw, processed poultry may include spoilage bacteria and foodborne pathogens. We evaluated different combinations of organic acid (OA) wash solutions for their ability to reduce bacterial contamination of raw chicken skin and to inhibit growth of spoilage bacteria and pathogens on skin during refrigerated storage. In experiment 1, raw chicken skin samples were dipped into a suspension of either 10(8) cfu/mL of Salmonella Typhimurium, Escherichia coli O157:H7, or Listeria monocytogenes for 30 s and then immersed in PBS or an OA wash solution mixture of 0.8% citric, 0.8% acetic, and 0.8% propionic acid (at equal wt/vol concentrations) for an additional 30 s. In experiment 2, three different concentrations of the OA wash solution (0.2, 0.4, and 0.6% at equal wt/vol concentrations) were tested against chicken skin samples contaminated with Salmonella Typhimurium. Viable pathogenic bacteria on each skin sample were enumerated after 1 and 24 h of storage at 4°C in both experiments. In experiment 3, skin samples were initially treated on d 1 with PBS or 2 concentrations of the OA mixture (0.4 and 0.8%), and total aerobic bacteria were enumerated during a 2-wk storage period. In all experiments, significant (P < 0.05) differences were observed when skin samples were treated with the OA wash solution and no spoilage organisms were recovered at any given time point, whereas increasing log10 numbers of spoilage organisms were recovered over time in PBS-treated skin samples. These results suggest that 0.2 to 0.8% concentrations of an equal-percentage mixture of this OA combination may reduce pathogens and spoilage organisms and improve food safety properties of raw poultry.

Evaluation of selected direct-fed microbial candidates on live performance and Salmonella reduction in commercial turkey brooding houses.

As effective probiotic Bacillus isolates that can increase BW gain (BWG) are identified, they may offer advantages in terms of stability, cost, and feed application over probiotics limited to drinking water application. Additionally, an effective direct-fed microbial (DFM) may offer an effective alternative to antibiotic growth promoters. Previously, 4 Bacillus isolates were identified and evaluated in our laboratory as potential DFM candidates. These isolates were shown to significantly increase BWG as well as reduce recovery of Salmonella after experimental infection. In the first experiment, isolates PHL-MM65 (a Bacillus laterosporus) and PHL-NP122 (a Bacillus subtilis) were evaluated using poults raised under commercial conditions. After 7 d of conventional brooding, poults were tagged, weighed, and placed in 1 of 4 replicate pens for each treatment group [negative control, 0.019% nitarsone, PHL-MM65 (10(6) spores/g of feed), or PHL-NP122 (10(6) spores/g of feed)] within the commercial turkey barn. At 23 d, poults were weighed and BW was calculated. Treatment with PHL-NP122 (853 g) or nitarsone (852 g) increased BW (P ≤ 0.05) compared with control (784 g), whereas treatment with PHL-MM65 (794 g) did not significantly improve BW. Also on d 23 of the trial, ceca were aseptically removed from 10 poults per pen and cultured for recovery of Salmonella. Both Bacillus isolates PHL-NP122 and PHL-MM65 resulted in a significant reduction (P ≤ 0.05) in the frequency of Salmonella by more than 25% compared with the controls. In a second experiment on a different farm, isolates PHL-NP122, PHL-RW33 (a B. subtilis), and PHL-B1 (a Bacillus licheniformis) were evaluated. None of the candidate Bacillus DFM or the group fed nitarsone had significantly different BW or BWG than untreated control. These data suggest that isolate PHL-NP122, when added as a DFM to turkey diets, may increase BW gain as well as nitarsone during the brooding phase of commercial turkey production.

The role of an early Salmonella Typhimurium infection as a predisposing factor for necrotic enteritis in a laboratory challenge model.

Necrotic enteritis (NE) caused by Clostridium perfringens (CP) in poultry is an important bacterial disease in terms of economic implications. The disease is multifactorial and is invariably associated with predisposing factors. In the present experiments, we investigated the potential predisposing role of neonatal Salmonella Typhimurium (ST) infection for NE-associated mortality in a laboratory challenge model. In two experiments, day-of-hatch chicks were randomly assigned to four groups: Group 1, nonchallenged control; Group 2, chickens received Eimeria maxima (EM) and CP; Group 3, chickens received EM and CP and were also challenged with ST at day 1 of age; Group 4, chickens received EM and CP and were also challenged with ST at day 17 of age. Challenged groups received an oral dose of EM at 18 days of age and CP (10(8) colony-forming units/chick) at 22-23 days of age. When compared to EM and CP, chicks challenged with ST (day 1) had increased NE-associated mortality and CP-associated lesion scores (P < 0.05) in both experiments. Furthermore, body weight and body weight gain were lower (P < 0.05) in chicks infected with ST (day 1) in the first experiment, even though no differences (P > 0.05) were observed in weight gain in the second experiment. Chicks challenged with ST (day 17) were similar to the EM and CP group in all of the above-mentioned parameters, indicating that a paratyphoid infection in younger chicks remarkably alters the susceptibility to secondary bacterial infections. Based on this work, the authors suggest that an ST infection early in the age of a chick may be important for altering susceptibility to NE, an observation that may be useful from the perspective of experimental reproduction of this disease and, perhaps, as an economically important reason to address the problem of paratyphoid Salmonella infections in young chicks.

Evaluation of Bacillus species as potential candidates for direct-fed microbials in commercial poultry.

Increasing sociopolitical concerns with antibiotic use have led to investigations of potential alternatives for food safety and growth promotion. Direct-fed microbials (DFM) including spore-based probiotics are amenable to feed inclusion and are extremely stable. We isolated several Bacillus spp. from environmental and poultry sources and tested them for their ability to reduce Salmonella in vitro. In a preliminary in vivo trial, day-of-hatch chicks and poults were randomly assigned to the following treatments (24 birds/treatment): control and one of 8 DFM candidates at 10(6) spores/g of feed. Chicks and poults were tagged, weighed, and orally challenged with Salmonella Typhimurium (ST). Body weight gain and ST recovery were measured 11 d posthatch. Total percentages of ST-positive crop and ceca were significantly lower (P < 0.05) in at least 3 DFM candidates compared with control. Additionally, beneficial effects on BW gain were observed in at least 5 DFM candidates (P < 0.05) compared with control. In a second study, birds treated with NP122 (identified as Bacillus subtilis) had significantly lower (P < 0.05) cecal ST than control and benefitted BW gain irrespective of the presence or absence of a Salmonella challenge. In conclusion, NP122 markedly reduced ST recovery and increased BW gain in both chicks and poults. This provides preliminary evidence that this isolate may have potential use as a DFM in poultry.

Effect of lactic acid bacteria probiotic culture for the treatment of Salmonella enterica serovar Heidelberg in neonatal broiler chickens and turkey poults.

In the present study, a series of experiments was conducted to evaluate the ability of a commercial probiotic culture (FloraMax, IVS-Wynco LLC, Springdale, AR) to reduce Salmonella enterica serovar Heidelberg (SH) in chicks and turkey poults. In experiments 1 and 2, chicks were randomly assigned to treatment groups and then challenged via oral gavage with SH. Chicks were treated 1 h following SH challenge with the probiotic culture via oral gavage. At 24 and 72 h posttreatment, cecal tonsils and ceca were collected for recovery and enumeration of enteric Salmonella Heidelberg, respectively. In experiment 3, day-of-hatch turkeys were randomly assigned to treatment groups and then challenged via oral gavage with SH. Poults were treated 1 h following challenge with the probiotic via oral gavage. At 24 and 72 h post probiotic treatment, cecal tonsils and ceca were collected for recovery and enumeration of enteric SH, respectively. The probiotic culture significantly reduced the incidence of SH in cecal tonsils at both time points in chicks in both experiments (P < 0.05). These data demonstrate that administration of probiotic 1 h post SH challenge significantly reduced the incidence of SH recovery from cecal tonsils of chicks compared with controls 24 and 72 h following treatment. Similarly, probiotic treatment resulted in significant reductions in the concentrations of SH within the ceca in both experiments. Although similar significant results were observed at both 24 and 72 h in experiment 3, it was clear that poults were more susceptible to SH colonization than chicks. Overall, a Lactobacillus-based probiotic significantly reduced Salmonella enterica serovar Heidelberg in chicks and turkey poults.