Enumeration and identification of bacteria in chicken semen

Three experiments were conducted to determine the bacteriological quality of chicken semen. Semen was collected from donor males, diluted, and surface inoculated onto seven different bacteriological media, from which randomly selected colonies were identified. Bacterial counts in semen averaged 5.14 log10 cfu/mL. Tryptic soy agar (TSA) was the best medium for the isolation of Gram-positive bacteria, whereas TSA + .3% bile salts (TSABS) and violet red bile agar + 1% glucose (VRBAG) were the best media for the isolation of Gram-negative and enteric bacteria. The genera of bacteria that were isolated depended on the medium that was used for isolation. The most frequently isolated genera included Escherichia, Staphylococcus, Micrococcus, Enterococcus, and Salmonella. Most of the bacteria that were isolated were endemic to poultry and were common environmental bacteria. This indicates that the environment and feed are important sources of bacterial contamination in broilers.

Effect of mating activity on the ability of Salmonella enteritidis to persist in the ovary and oviduct of chickens

Experiments were undertaken to determine whether female leghorn chickens that had been mated had a lower incidence of salmonellae colonization in the ovary, oviduct, internal organs, and eggs than did unmated birds from the same flock when both were inseminated with Salmonella enteritidis-contaminated semen. Eggs were sampled at approximate 3-day intervals, and fecal samples were taken at 24 hours and 7 days after insemination. Fourteen days following insemination, hens were euthanatized and the ovary, oviduct, liver, spleen, gall bladder, and ceca were removed. None of the previously mated hens had salmonellae present at any sampling time. Virgin birds showed salmonellae colonization in all samples. This indicates that mating activity and the environment of females offers some protection against salmonellae colonization in the reproductive tract.

Salmonella colonization and shedding patterns of hens inoculated via semen

Two experiments were conducted to determine the effect of inseminating hens with semen contaminated with marker strains of Salmonella enteritidis and S. typhimurium. Eggs were collected and examined for salmonellae. In Expt. 1, 3/57 (5.3%) of eggs from S. enteritidis-challenged hens and 2/50 (4.0%) of eggs from S. typhimurium-challenged hens were contaminated with salmonellae. Salmonellae were recovered from only the shell. In Expt. 2, however, no eggs from S. typhimurium-challenged hens were contaminated; 2/73 (2.7%) of the eggs from S. enteritidis-challenged hens were contaminated. In Expt. 1, S. typhimurium was present in 30% of the oviducts and 20% of the ovaries; S. enteritidis was present in 20% of the oviducts and 20% of the ovaries. No salmonellae-containing oviducts or ovaries were found in either S. enteritidis- or S. typhimurium-challenged hens in Expt. 2. S. enteritidis and S. typhimurium were found in fecal samples taken 24 hr after insemination, but only S. enteritidis was fecally shed 7 days after insemination (20% in Expt. 1). Data indicate that semen may severe as a vehicle for transmission of salmonellae to the hen, which may result in sporadic production of contaminated eggs.

Recovery of Salmonellae from Chilled Broiler Carcasses as Affected by Rinse Media and Enumeration Method

Distilled water (DW) and 0.85% NaCl (PS) were evaluated as carcass rinse media for recovery of total aerobic bacteria (APC), total coliforms (TC), Escherichia coli , and salmonellae from broiler carcasses. Salmonellae were enumerated by two methods, most-probable-number (MPN) and centrifugation-plating onto dulcitol novobiocin agar (DBN). Commercially processed chilled broiler carcasses (10/trial, 3 trials) were aseptically cut in half, and each half was rinsed (1 min) with either 250 ml DW or PS. Carcass rinses were recovered and analyzed for populations of APC, TC, E. coli , and salmonellae. Recovery of APC, TC, and E. coli were not affected (P>.05) by rinse media; however, significant trial effects were present. Recovery of salmonellae was influenced by rinse media as well as by enumeration method. Using the MPN procedure, salmonellae were detected on 20 and 27% of carcass halves using PS and DW, respectively, whereas with DBN, salmonellae were recovered from 33% of PS-rinsed carcass halves and none of those rinsed with DW. Incidence of salmonellae on individual carcass halves did not correlate between either the two enumeration methods or rinse media. With both enumeration methods, the extent of salmonellae contamination was <1 CFU/ml of rinse media. Rinsing carcasses with PS offered no advantages for recovery of APC, TC, and E. coli ; however, salmonellae recovery on DBN was enhanced by PS as compared to DW rinse.

Comparison of different anticoccidials on processing characteristics and parts yield of broiler chickens

Broilers were grown to 42 days of age on diets supplemented with salinomycin (60 mg/kg), monensin (99 mg/kg), or halofuginone (3 mg/kg) and continued on unmedicated diets to 49 days of age. There were no significant (P greater than .05) differences among anticoccidials in final body weight, feed conversion, or mortality rates. Samples of birds were processed for dressing percentage and parts yield. Both males and females fed salinomycin had significantly higher breast meat yield as a percentage of postchill weight than those fed halofuginone but not those fed monensin; differences were not significant for breast meat yield of males or females fed monensin or halofuginone. Males fed halofuginone had significantly heavier leg quarters than those fed salinomycin but not those fed monensin. Females fed salinomycin had significantly higher water uptake during chill than those fed monensin or halofuginone. Results of the present study indicate that the anticoccidial used in growing broilers may influence some carcass yield parameters.

Research note: evaluation of the Report Salmonella visual immunoassay for detection of salmonellae on raw poultry carcasses

Two trials were conducted to compare the standard culture procedure and the Report Salmonella Visual Immunoassay for detection of salmonellae in rinse fluid recovered from raw poultry carcasses. Both assays were evaluated with and without preenrichment in lactose broth prior to enrichment in selenite cystine broth. Live birds were inoculated via the drinking water prior to processing to ensure a high degree of carcass contamination. Prechill carcasses were sampled using 200 mL of sterile water. Results indicated that lactose preenrichment was not necessary for salmonellae evaluation using standard culture procedures. However, the Report assay produced fewer false-negative results if lactose preenrichment was utilized.

Effects of D-mannose on incidence and levels of salmonellae in ceca and carcass samples of market age broilers

Two similar trials were conducted to evaluate the effects of 2.5% d-mannose (DM) in the drinking water of broilers for the first 10 days on incidence and levels of salmonellae in the ceca and on the carcass at market age. Controls received drinking water with no DM. Birds were reared on used litter in floor pens and were inoculated via the drinking water with 10(8) cfu/mL Salmonella typhimurium (ATCC 14028) on Day 3. At 49 days, 60 birds per treatment were processed and the ceca contents and prechill carcass were evaluated for salmonellae incidence by the most probable number (MPN) method. Results were inconclusive: level of salmonellae in the ceca contents and carcass rinse was significantly lower in control samples than in DM samples in one of the two trials; the reverse was true in the other trial.

Effect of litter condition on microbiological quality of freshly killed and processed broilers

Two similar trials were conducted to evaluate the effects of litter condition on microbiological quality of freshly killed (feathers intact) and processed broilers. Commercial broilers were reared to 49 days of age on new or previously used litter. Birds in half of the replicate pens were inoculated with Salmonella typhimurium via the drinking water on Days 2, 7, 14, and 21. Broilers were sampled at the following processing locations: postkill, postpick, prechill, and postchill. Postchill carcasses from birds raised on previously used litter did not have significantly different aerobic plate counts, levels of coliforms, or numbers of salmonellae as compared with carcasses from birds raised on new litter. Live bird inoculation did significantly increase levels of salmonellae on the fully processed carcass.

Effects of formic acid or calcium formate in feed on performance and microbiological characteristics of broilers

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.

Effects of different antibiotics on performance, processing characteristics, and parts yield of broiler chickens

Broilers were grown to 49 days of age on diets supplemented with bambermycins (BAM, 2.2 ppm), bacitracin methylene disalicylate (BMD, 27.5 ppm), virginiamycin (VM, 11 ppm), or an unmedicated control. Samples of birds were processed for dressing percentage and parts yield. There were no significant (P greater than .05) effects of antibiotics on final body weight, feed conversion, or mortality. In male broilers, BMD and VM significantly (P less than or equal to .05) increased dressing percentage and percentage yield and reduced the skeletal rack as a percentage of postchill weight compared to those fed the nonmedicated control. All antibiotics significantly increased breast skin weight and breast skin as a percentage of postchill weight of as compared with those fed the unmedicated control. In female broilers, BAM and BMD significantly increased dressing percentage and percentage yield and increased breast weight and breast as percentage of postchill weight as compared with those fed the unmedicated control diet. Females fed BMD also had significantly heavier leg quarters and breast skin than those fed the unmediated control. Females fed VM had increased breast skin weight and breast skin as a percentage of postchill weight than those fed the unmedicated control. The results of the present study indicate that antibiotics may influence dressing percentage and parts yield in the absence of improvements in body weight gain or feed utilization.

The use of carcass halves for reducing the variability in salmonellae numbers with broiler-processing trials

Two similar trials were conducted in order to compare the variability in the number of salmonellae between the right and left sides of individual broiler carcasses with the variability among carcasses. In both trials, the variation between carcass sides was equal and was significantly less than the variation among carcasses. For trials involving bactericidal treatment, the authors would suggest that the utilization of carcass halves (one side for control, the other for treatment) would allow for a more-sensitive evaluation of treatment effects.

Effects of a buffered propionic acid in diets on the performance of broiler chickens and on microflora of the intestine and carcass

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)

Production and Processing Studies to Reduce the Incidence of Salmonellae on Commercial Broilers 1, 2

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.

Comparison of the DNA Probe to Culture Methods for the Detection of Salmonella on Poultry Carcasses and Processing Waters 1

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 pre-chill 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.