C. L. Woodward

The Influence of a Fructooligosaccharide Prebiotic Combined with Alfalfa Molt Diets on the Gastrointestinal Tract Fermentation, Salmonella Enteritidis Infection, and Intestinal Shedding in Laying Hens

Molting is a natural process, which birds undergo to rejuvenate their reproductive organs. The US poultry egg production industry has used feed withdrawal to effectively induce molt; however, susceptibility of Salmonella Enteritidis has encouraged the development of alternative methods. Previous research conducted in our laboratory showed that alfalfa is effective at molt induction and provides equivalent postmolt production numbers and quality when compared with feed withdrawal. In the attempt to further increase the efficacy of alfalfa molt diet and decrease the chicken susceptibility to Salmonella Enteritidis during molt, fructooligosaccharide (FOS) was added to a combination of 90% alfalfa and 10% layer ration in 2 levels (0.750 and 0.375%). Ovary and liver colonization by Salmonella Enteritidis in 3 and 2 of the 4 trials, respectively, were reduced (P <or= 0.05) in hens fed FOS-containing diets compared with hens subjected to feed withdrawal. Significant decreases in ce-cal Salmonella Enteritidis counts were also observed in 2 of the 4 trials. In 3 of the 4 trials, the same diets did not affect (P > 0.05) the production of cecal total volatile fatty acids when compared with hens undergoing feed withdrawal. However, in all 3 alfalfa molt diets, the concentrations of lactic acid were greater (P <or= 0.05) than hens with feed withdrawal, but no differences (P > 0.05) were observed among hens fed alfalfa combined with FOS and hens fed alfalfa/layer ration without FOS. Overall, given the similarities between hens fed 0.750% FOS (H) and 0.375% FOS (L), molt diets combined with the lower level of FOS should be sufficient.

Detection of methane and quantification of methanogenic archaea in faeces from young broiler chickens using real‐time PCR

Aims:  To detect the presence of methanogens in the faeces of broiler chicks during the first 2 weeks of age.

In Vitro Fermentation Response of Laying Hen Cecal Bacteria to Combinations of Fructooligosaccharide Prebiotics with Alfalfa or a Layer Ration

The objective of this in vitro study was to evaluate the effects of combining a prebiotic with alfalfa on fermentation by laying hen cecal bacteria. Cecal contents from laying hens were diluted to a 1:3,000 concentration with an anaerobic dilution solution and added to serum tubes filled with ground alfalfa or a layer ration with or without fructooligosaccharide (FOS) prebiotic. Samples were processed in an anaerobic hood, pressurized by using a pressure manifold, and incubated at 37 degrees C. Volatile fatty acid (VFA) and lactic acid concentrations were quantified at 6 and 24 h of substrate fermentation. In this study, fermentation of alfalfa resulted in greater production of acetate, VFA, and lactic acid compared with the layer ration. Although with a relative inconsistency in data between trials, the amendment of FOS to both alfalfa and the layer ration appeared to further increase fermentation as demonstrated by overall higher propionate, butyrate, VFA, and lactic acid concentrations. The effect was more pronounced after 24 h of fermentation, implying time constraints for the optimal production of fermentation products in the chicken gastrointestinal tract. These data indicate that in vitro cecal fermentation can be enhanced by the addition of FOS.

Environmental Dissemination of Foodborne Salmonella in Preharvest Poultry Production: Reservoirs, Critical Factors, and Research Strategies

The impact of potential pathogenic foodborne Salmonella spp. in poultry production environments is of paramount importance, considering its implications for human health. Most of what is known about this organism under these environmental conditions is based on indirect evidence. The overall focus of this review is on the biology of potentially pathogenic foodborne Salmonella spp. in poultry environments. This is not just because of the implications regarding pathogenic Salmonella spp. for poultry production and food safety but because Salmonella spp. behavior may serve as a model for understanding general bacterial pathogen persistence in animal agricultural environments. This will help meet a long-term need to develop a comprehensive ecological picture of the contamination potential, growth, survival, and genetic stability of pathogens in poultry and other animal production environments. This will in turn lead to a better understanding of the environmental and health impacts of foodborne Salmonella spp. dissemination in animal production environments.

Litter and aerosol sampling of chicken houses for rapid detection of Salmonella typhimurium contamination using gene amplification.

Rapid screening of poultry houses for contamination is critical for Salmonella control. Use of air filter sampling has great potential for efficient and reliable monitoring of Salmonella spp., as it could represent an entire poultry house and solve sample-size problems. Two sampling methods (litter and air filter) were compared for detection in four chicken pens inoculated with a S. typhimurium antibiotic resistant strain. Salmonella levels in both litter and air filter samples were determined by PCR amplification and by conventional enrichment. Although amplified DNA was not directly detected, amplified DNA could be detected using a dual probe hybridization sensor. The ratio of the positive samples to total samples determined by gene amplification was much lower than that obtained by conventional enrichments (29/128 versus 102/128 samples). However, the ratio obtained by gene amplification with air filter samples was greater than that with litter samples (26/64 versus 3/64). These results demonstrate that the air filter sampling method is an alternative method of Salmonella detection in poultry house using PCR gene amplification protocol. Journal of Industrial Microbiology & Biotechnology (2000) 24, 379–382.

Quantification of total and bioavailable lysine in feed protein sources by a whole-cell green fluorescent protein growth-based Escherichia coli biosensor

Using a fluorescent whole-cell Escherichia coli biosensor previously developed in our laboratory, we determined total and bioavailable lysine in four feed ingredients (soybean, cottonseed, meat and bone meal, and sorghum) and three complete feeds (chick starter and finisher, and swine starter). The same feed sources were analyzed for total lysine by high performance liquid chromatography (HPLC) and bioavailable lysine by chick bioassay. No significant differences were found between bioavailable lysine estimates for soybean, cottonseed, meat and bone meal, chick starter and finisher, and swine starter obtained by the fluorescent E. coli biosensor and chick bioassay. Except for sorghum, the E. coli biosensor estimates for total lysine were highly comparable to those obtained by HPLC. Comparisons were also conducted between conventionally performed optical density-based and the newly developed fluorescence-based lysine assay. The lack of significant differences in data obtained for total and bioavailable lysine by both detection modes indicated reliance and accuracy of the fluorescent E. coli biosensor. Overall results suggest that the microbial assay based on green fluorescent protein fluorescence represents a promising alternative method for lysine quantification.

Growth kinetics response of a Salmonella typhimurium poultry marker strain to fresh produce extracts

The purpose of this research was to assess growth response of a Salmonella typhimurium poultry marker strain to fresh homogenized vegetables. Salmonella growth rates were significantly higher (p<0.05) in jalapeno extracts than any other produce extract examined. Growth rates on samples of broccoli and lettuce extracts were greater (p<0.05) than the respective growth rates on bell pepper and tomato. Broccoli extracts yielded the highest extent of growth (4 h optical density) followed by jalapeno and bell pepper extracts. From this study, it appears that fresh produce extracts have different abilities to significantly alter growth response in Salmonella. This could potentially be explained by the variations of pH, nutrient availability to the bacteria, or unknown components found within fresh produce.

Use of a Salmonella typhimurium hilA fusion strain to assess effects of environmental fresh water sources on virulence gene expression.

Many fruits and vegetables are irrigated with water from rivers, lakes and even wastewater systems. Irrigation may be a route for the introduction of Salmonella. Our objectives in this study were to determine survivability and virulence expression in a strain of Salmonella typhimurium when exposed to environmental water sources. Virulence expression was measured using a beta-galactosidase assay on a hilA:lacZY fusion strain of S. typhimurium. Water samples for environmental impact studies were taken from a local pond and specific sites along the Rio Grande River, which serves as a source of irrigation water in southern Texas. There was a significant difference (p<0.05) of virulence expression among the water sites. Certain regions along the Rio Grande River yielded greater amounts of beta-galactosidase activity than others. All sites yielded at least a two-fold greater virulence response than S. typhimurium grown in brain heart infusion. Salmonella survivors were enumerated as colony forming units (CFU)/ml as plated on a selective medium for the duration of 1 week and beta-galactosidase assays were performed to determine a possible correlation between culturable cells and virulence gene expression. Bacterial cells remained viable but decreased after 7 days incubation. In conclusion, water sampled at specific locations and at different times water samples exhibited differences in virulence expression in S. typhimurium.

Application of an Escherichia coli green fluorescent protein - based lysine biosensor under nonsterile conditions and autofluorescence background

Aims:  To examine the utility of an Escherichia coli green fluorescent protein (GFP) containing biosensor for quantification of bioavailable lysine in selected feed samples under nonsterile conditions and to estimate the background fluorescence of analyzed feed samples and evaluate the risk of confounding GFP emission from the lysine assay organism.

Recovery of a marker strain of Salmonella typhimurium in litter and aerosols from isolation rooms containing infected chickens

Abstract Screening of poultry flocks for foodborne pathogen Salmonella contamination is critical for Salmonella control in preharvest stages of poultry production. In this study, two sampling methods (litter and air filter) were compared for detection of S. typhimurium from experimentally infected chicks some of which had received either a probiotic competitive exclusion culture or transfer of cecal contents from salmonellae‐free adult birds. At 4, 9, and 11 days after inoculation, S. typhimurium samples were enumerated by selective plating. For both types of sampling, the control birds yielded the greatest levels of environmental contamination followed by the samples from the probiotic inoculated birds with the birds receiving the cecal transfer culture having the lowest levels of contamination. Although the two sampling methods responded in a similar fashion, detection sensitivity needs to be increased for air filter sampling.