A buffered propionic acid (BPA) was added to broiler diets fed in floor pens with litter. The BPA was fed continuously at 0, .2, .4, and .8% in Trial 1 and at 0 and .4% in Trial 2. The BPA was also fed at .4% for the last 7 days in Trial 2. Natural salmonellae exposure versus periodic dosage with Salmonella typhimurium was compared in Trial 2. In Trial 1, the BPA supplement had no adverse effects on growth, feed utilization, or abdominal fat with a significant (P less than or equal to .05) increase in the female dressing value at .8% of buffered propionic acid. The total number of coliforms and of Escherichia coli in the duodenum were significantly reduced by .4% BPA; in the jejunum, by all levels used in the trials; and in the ileum, by .4% and .8% of buffered propionic acid. The intestinal pH was not influenced by the BPA addition. In Trial 2, the BPA at .4% fed continuously had no adverse effect on growth, feed utilization, the abdominal fat of females, or the dressing percentage of males while significantly reducing the abdominal fat for males and increasing the dressing percentage for females. Feeding .4% BPA for the last 7 days had no effect on any of these parameters. Periodic dosage with S. typhimurium had no effect on body weight, feed utilization, or abdominal fat and significantly increased the dressing percentage. There was a significant interaction between the Salmonella dosage and the time of feeding BPA on dressing percentage.(ABSTRACT TRUNCATED AT 250 WORDS)

Three experiments were conducted to determine the effects of feeding broilers formic acid (FA) or calcium formate (CF) on performance and microbiological characteristics of broilers. Live bird performance was not adversely affected by feeding up to 1.0% FA or 1.45% CF. In Experiment 1, levels of salmonellae in carcass and cecal samples were significantly reduced by feeding birds .36% CF. Salmonellae were not isolated from any of the carcasses of birds fed .36% CF. Similar reductions were not noted for total organisms or presumptive coliforms. In Experiment 2, feeding .36% CF nonsignificantly reduced levels of salmonellae in carcass and cecal samples, but again, levels of total organisms and coliforms were not reduced. In Experiment 3, salmonellae in the ceca or in the carcass rinse fluid were not reduced by feeding .36% CF.

A series of experiments have been conducted at the University of Arkansas over the last two years in efforts to decrease the incidence of salmonellae on commercial broilers. These experiments have concentrated on feeding trials in efforts to alter intestinal microflora, and processing trials in which chemical additives have been evaluated. A buffered propionic acid compound was fed at various concentrations for specific time periods and the cecal tonsils, small intestine, litter, and processed carcasses were tested for salmonellae and other organisms. In a separate series of trials a variety of chemicals were added to the scald, chill, scald and chill, or used as pre- or post-chill dips or sprays in efforts to decrease carcass contamination with salmonellae and extend product shelflife. Feeding trials indicate that the addition of a buffered propionic acid can alter intestinal microflora and decrease contamination of the processed carcass without adversely affecting live bird performance. Processing trials indicate that certain chemicals such as lactic acid can be used in a variety of ways to either decrease or eliminate salmonellae from the carcass and extend shelflife of processed broilers. However, some chemicals at high concentrations may produce undesirable organoleptic characteristics.

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In a series of five experiments a total of 269 broiler carcass and chill tank water samples were tested for the presence of Salmonella using the DNA probe and the standard cultural method. Carcasses were sampled using a whole carcass rinse technique. Samples consisted of pre-(48) and post-chill (103) carcasses, and pre-chill (48) and chill (70) tank water. Samples to be evaluated with the DNA probe were subjected to three preenrichment/ enrichment procedures to determine the most accurate and reliable enrichment procedure to use with the DNA probe assay. Direct enrichment in Selenite Cystine followed by 24 h incubation in Gram Negative broth allowed for recovery of 0.03 salmonellae/ml from carcass rinse and from pre-chill water using either the standard cultural method or the DNA probe. Preenrichment in Lactose broth produced inaccurate results for prechill carcass and pre-chill water samples using the DNA probe assay, and may be due to extreme microbiological competition. No false positive results were obtained using the DNA probe assay for any of the four sample types.The food industry, governmental regulatory agencies, and the consumer have a vital interest in decreasing the incidence of salmonellosis and other foodborne diseases. Contamination of chicken carcasses with Salmonella is a source of human salmonellosis and is of continuing concern to both the poultry industry and public health authorities (17). Present technology utilized in slaughtering plants cannot guarantee a salmonellae-free finished product. Because of the increased public awareness of food poisoning bacteria and increased scrutiny by regulatory agencies, development of methods for rapid and reliable detection of foodborne Salmonella is indicated (18).Rapid methods including fluorescent antibody techniques (30,34,48,59,60), radioisotopic immunoassays (31,50,57), enrichment serology techniques (3, 5, 33, 34, 56, 57), enzyme immunoassays (39,45,58,63) screening and/or identification of various pathogenic organisms including Salmonella. Each of these methods is based on various characteristics of the organism. These rapid methods of analysis provide for the timely identification of contaminated products and reduce costs associated with storage of products pending microbiological clearance.It is possible to obtain results within 48 h using the DNA probe. This includes the time necessary for steps that must be completed prior to performing the actual DNA hybridization assay (25,26). Use of DNA-DNA hybridization for the detection of bacteria in clinical applications has been described by several groups. Encoded enterotoxins were cloned and used to detect enterotoxigenic E. coli both in colonies and directly from stools of patients suffering from acute diarrhea (46). A similar system has been used to detect enteropathogenic E. coli in food samples (35). DNA hybridization has also been applied to the detection of Leishamania spp., hepatitis B virus, cytomegalovirus, and 6,8,64).Cloned DNA fragments from S. typhimwium have shown high specifi...