K. E. Anderson

Ovarian Adenocarcinomas in the Laying Hen and Women Share Similar Alterations in p53, ras, and HER-2/neu

We examined alterations in the p53 tumor suppressor gene and the ras and HER-2/neu oncogenes in chicken ovarian cancers to determine if these tumors have genetic alterations similar to those in human ovarian adenocarcinomas. Mutations in the p53 tumor suppressor gene and the H-ras and K-ras oncogenes were assessed by direct sequencing in 172 ovarian cancers obtained from 4-year-old birds enrolled at age 2 in two separate 2-year chemoprevention trials. Birds in trial B had approximately twice as many lifetime ovulations as those in trial A. Immunohistochemical staining for the HER-2/neu oncogene was done on a subset of avian ovarian and oviductal adenocarcinomas. Alterations in p53 were detected in 48% of chicken ovarian cancers. Incidence of p53 alterations varied according to the number of lifetime ovulations, ranging from 14% in trial A to 96% in trial B (P < 0.01). No mutations were seen in H-ras, and only 2 of 172 (1.2%) tumors had K-ras mutations. Significant HER-2/neu staining was noted in 10 of 19 ovarian adenocarcinomas but in only 1 of 17 oviductal adenocarcinomas. Similar to human ovarian cancers, p53 alterations are common in chicken ovarian adenocarcinomas and correlate with the number of lifetime ovulations. Ras mutations are rare, similar to high-grade human ovarian cancers. HER-2/neu overexpression is common and may represent a marker to exclude an oviductal origin in cancers involving both the ovary and oviduct.

Cryogenic gas for rapid cooling of commercially processed shell eggs before packaging

Research was initiated to evaluate the effects on egg quality and microbial counts of rapidly cooling eggs by using cryogenic gases. Four trials were conducted utilizing a 2 × 2 factorial design with cryogenic cooling and Pseudomonas inoculation as the main variables. The 1440 eggs used in each trial were evaluated for cracked shells, Haugh units, and albumen pH. Cryogenically cooled treatment groups were successfully cooled from 37°C to 7°C in significantly less time than in a traditionally cooled pallet. The Haugh unit values obtained from traditionally cooled eggs were significantly (P > .001) lower than those from cryogenically cooled eggs. There was no significant difference in the albumen pH of the two groups. Internal and external bacterial counts revealed significantly fewer bacteria in the interior of cryogenically cooled eggs than in the interior of traditionally cooled eggs. However, after a 30-day storage period at 7°C, no difference was found in external and internal bacterial contamination rates. The results of this trial suggest that rapid cooling with cryogenic gases could be used in conjunction with current commercial egg processing to cool eggs prior to packaging. The successful commercial application of this procedure would reduce egg temperatures as well as the likelihood of Salmonella enteritidis growth in or on eggs. Thus, consumers would be provided with safer commercially processed shell eggs. In addition, the Haugh unit data indicate that rapid cooling with cryogenic gases enhances the quality of commercially processed shell eggs.

Prevalence of coliforms, Salmonella, Listeria, and Campylobacter associated with eggs and the environment of conventional cage and free-range egg production

There is a desire by US consumers for eggs produced by hens in alternative production systems. As the retail shell-egg market offers these products to accommodate consumer demands, additional information is needed to ensure processing methodologies result in safe eggs from all egg sources. A study was conducted to determine if there were differences in the prevalence of coliforms, Salmonella, Listeria, and Campylobacter on and within eggs and in the environment of a sister flock of conventional cage and free-range laying hens. Microbial sampling occurred approximately every 6 wk between 20 and 79 wk of age. A random sampling of typical coliform colonies produced 371 viable isolates for biochemical identification. Twenty-nine genera or species of bacteria were identified. There was a significantly greater (P < 0.0001) prevalence of Campylobacter in the free-range nest box swabs compared with that in the free-range grass and conventional cage swab samples (number of positives: 8 nest box, 1 grass, 0 cage). Seven isolates of Listeria innocua were detected with no significant difference in prevalence between the treatments. Isolates were associated with eggshells (2 free-range floor, 1 cage) and the free-range environment (2 nest box, 2 grass). There were 21 Salmonella isolates detected between all sample locations, with no significant difference in the prevalence of Salmonella detection between the treatments. Additional studies are needed to fully understand the effect of alternative production methods on the prevalence of pathogens and coliforms associated with nest-run eggs and the production environment.

Comparison of fatty acid, cholesterol, and vitamin A and E composition in eggs from hens housed in conventional cage and range production facilities

The public perceives that the nutritional quality of eggs produced as free range is superior to that of eggs produced in cages. Therefore, this study compared the nutrient content of free-range vs. cage-produced shell eggs by examining the effects of the laboratory, production environment, and hen age. A flock of 500 Hy-Line Brown layers were hatched simultaneously and received the same care (i.e., vaccination, lighting, and feeding regimen), with the only difference being access to the range. The nutrient content of the eggs was analyzed for cholesterol, n-3 fatty acids, saturated fat, monounsaturated fat, polyunsaturated fat, β-carotene, vitamin A, and vitamin E. The same egg pool was divided and sent to 4 different laboratories for analysis. The laboratory was found to have a significant effect on the content of all nutrients in the analysis except for cholesterol. Total fat content in the samples varied (P < 0.001) from a high of 8.88% to a low of 6.76% in laboratories D and C, respectively. Eggs from the range production environment had more total fat (P < 0.05), monounsaturated fat (P < 0.05), and polyunsaturated fat (P < 0.001) than eggs produced by caged hens. Levels of n-3 fatty acids were also higher (P < 0.05), at 0.17% in range eggs vs. 0.14% in cage eggs. The range environment had no effect on cholesterol (163.42 and 165.38 mg/50 g in eggs from caged and range hens, respectively). Vitamin A and E levels were not affected by the husbandry to which the hens were exposed but were lowest at 62 wk of age. The age of the hens did not influence the fat levels in the egg, but cholesterol levels were highest (P < 0.001) at 62 wk of age (172.54 mg/50 g). Although range production did not influence the cholesterol level in the egg, there was an increase in fat levels in eggs produced on the range.

Internal and External Bacterial Counts from Shells of Eggs Washed in a Commercial-Type Processor at Various Wash-Water Temperatures†

The effects of two egg holding temperatures (15.5 and 26.7°C) and three wash-water temperatures (15.5, 32.2, and 48.9°C) on internal and external shell surface bacterial counts were tested by using a commercial-type egg-processing unit. Two experiments consisting of five trials, each of which included 360 eggs per treatment for a total of 2,160 per trial, were conducted during two seasons (summer and winter) for a total of 10 replicates per experiment. During the performance of each replicate, counts from tryptic soy agar (TSA) and MacConkey agar (MAC) were obtained from 10 egg samples which were collected prior to processing (prewash), immediately after washing (postwash), and after as-day cooling period at 7.2°C (postcool). No growth was observed on MAC plates in either experiment, indicating that fewer than 100 counts were detected. No significant differences (P > 0.05) were observed in the prewash, postwash, or postcool internal shell counts of eggs held at l5.5°C compared to internal counts of shells of eggs held at 26.7°C. Likewise, no significant differences (P > 0.05) were observed in the prewash, postwash, or postcool internal shell counts obtained from eggs washed in l5.5°C water compared with internal shell counts obtained from eggs washed in water at 32.2 or 48.9°C. On the basis of our data, spray washing eggs in l5.5°C water does not appear to increase internal shell bacterial counts. Because warm or hot wash water increases egg temperatures markedly, a reexamination of cold-water processing procedures may be in order.

Physical quality and composition of retail shell eggs

There are a number of specialty shell eggs available to consumers in the US retail market. A survey consisting of white and brown large shell eggs with various production and nutritional differences (traditional, cage-free, free-roaming, pasteurized, nutritionally enhanced, and fertile) was conducted to determine if physical quality and compositional differences exist. Identical brands of eggs were purchased from the same retail outlets on 3 occasions (replicates) in a single city. The average range of time from processing to purchase for all eggs was 7.67 to 25.33 d, with traditional white eggs in retail having the shortest time. Haugh unit values ranged from 66.67 (cage-free, docosahexaenoic acid, and n-3 enhanced) to 84.42 (traditional white). Albumen height followed a similar pattern. Egg weight was greater for brown eggs (61.12 vs. 58.85 g). Brown eggs also had greater static compression shell strength than white eggs (4,130.61 vs. 3,690.31 g force). Vitelline membrane strength was greatest for traditional brown eggs (2.24 g force). Percentage of total solids and crude fat was greatest in the cage-free, n-3-enhanced white eggs (25.07 and 11.71%, respectively). Although significant differences were found between white and brown shell eggs and production methods, average values for quality attributes varied without one egg type consistently maintaining the highest or lowest values.

Colonization of internal organs by Salmonella Enteritidis in experimentally infected laying hens housed in conventional or enriched cages

More human illnesses caused by Salmonella enterica subspecies enterica serovar Enteritidis throughout the world have been linked to the consumption of contaminated eggs than to any other food vehicle. Deposition of this pathogen in the edible contents of eggs occurs when systemic infections of laying hens involve colonization of reproductive organs. In recent years, the consequences of different housing systems for laying flocks have become the focus of international attention from both animal welfare and public health perspectives. Nevertheless, many questions remain unresolved regarding the food safety implications of various laying hen production systems. The present study assessed the effects of 2 different housing types (conventional cages and colony cages enriched with perching, nesting, and scratching areas) on the invasion of internal organs by Salmonella Enteritidis in experimentally infected laying hens. In 2 trials, groups of laying hens housed in each cage system were orally inoculated with doses of 1.0 × 10(7) cfu of Salmonella Enteritidis. At 5 to 6 d postinoculation, hens were euthanized and samples of internal organs were removed for bacteriologic culturing. For both trials combined, Salmonella Enteritidis was recovered from 95.3% of cecal samples, with no significant differences observed between housing systems. However, Salmonella Enteritidis was detected at significantly (P < 0.05) higher frequencies from hens in conventional cages than from hens in enriched cages for samples of livers (96.9 vs. 75.0%), spleens (93.8 vs. 53.1%), ovaries (25.0 vs. 10.4%), and oviducts (19.8 vs. 2.1%). These results demonstrate that differences in housing systems for egg-laying flocks can affect the susceptibility of hens to colonization of internal organs by Salmonella Enteritidis.

The effects of commercial cool water washing of shell eggs on Haugh unit, vitelline membrane strength, aerobic microorganisms, and fungi

Current egg washing practices use wash water temperatures averaging 49 degrees C and have been found to increase internal egg temperature by 6.7 to 7.8 degrees C. These high temperatures create a more optimal environment for bacterial growth, including Salmonella Enteritidis if it is present. Salmonella Enteritidis is the most common human pathogen associated with shell eggs and egg products. Its growth is inhibited at temperatures of 7.2 degrees C and below. The objective of this study was to determine if commercially washing eggs in cool water would aid in quickly reducing internal egg temperature, preserving interior egg quality, and slowing microbial growth. During 3 consecutive days, eggs were washed using 4 dual-tank wash water temperature schemes (HH = 49 degrees C, 49 degrees C; HC = 49 degrees C, 24 degrees C; CC = 24 degrees C, 24 degrees C; CH = 24 degrees C, 49 degrees C) at 2 commercial processing facilities. A 10-wk storage study followed, in which vitelline membrane strength, Haugh unit, and aerobic microorganisms and fungi (yeasts and molds) were monitored weekly. As storage time progressed, average Haugh unit values declined 14.8%, the average force required to rupture the vitelline membrane decreased 20.6%, average numbers of bacteria present on shell surfaces decreased 11.3%, and bacteria present in egg contents increased 39.5% during storage. Wash water temperature did not significantly affect Haugh unit values, vitelline membrane strength, or the numbers of aerobic microorganisms and fungi within the shell matrices of processed eggs. Results of this study indicate that incorporating cool water into commercial shell egg processing, while maintaining a pH of 10 to 12, lowers postprocessing egg temperatures and allows for more rapid cooling, without causing a decline in egg quality or increasing the presence of aerobic microorganisms and fungi for approximately 5 wk postprocessing.

Contamination of eggs by Salmonella Enteritidis in experimentally infected laying hens housed in conventional or enriched cages.

Both epidemiologic analyses and active disease surveillance confirm an ongoing strong association between human salmonellosis and the prevalence of Salmonella enterica subspecies enterica serovar Enteritidis in commercial egg flocks. The majority of human illnesses caused by this pathogen are attributed to the consumption of contaminated eggs. Animal welfare concerns have increasingly influenced commercial poultry production practices in recent years, but the food safety implications of different housing systems for egg-laying hens are not definitively understood. The present study assessed the effects of 2 different housing systems (conventional cages and colony cages enriched with perching and nesting areas) on the frequency of Salmonella Enteritidis contamination inside eggs laid by experimentally infected laying hens. In each of 2 trials, groups of laying hens housed in each cage system were orally inoculated with doses of 1.0 × 10(8) cfu of Salmonella Enteritidis. All eggs laid between 5 and 25 d postinoculation were collected and cultured to detect internal contamination with Salmonella Enteritidis. For both trials combined, Salmonella Enteritidis was recovered from 3.97% of eggs laid by hens in conventional cages and 3.58% of eggs laid by hens in enriched cages. No significant differences (P > 0.05) in the frequency of egg contamination were observed between the 2 housing systems.

Comparison of environmental and egg microbiology associated with conventional and free-range laying hen management

Eggs from alternative production practices are a growing niche in the market. Meeting consumer requests for greater diversity in retail egg options has resulted in some unique challenges such as understanding the food safety implications of eggs from alternative production practices. A study was conducted to determine what, if any, differences exist between nest run conventional cage-produced eggs and free range-produced eggs. A sister flock of brown egg layers was maintained in conventional cage and free-range production with egg and environmental sampling every 6 wk from 20 to 79 wk of age. Aerobic, coliform, and yeast and mold populations were monitored. Environmental microbial levels were not always indicative of egg contamination levels. When significant differences (P < 0.05 and P < 0.0001, dependent on season) were observed among treatments for coliforms, shell contamination levels of free-range nest box eggs and free-range floor eggs were always greater than those of conventional cage eggs, which remained low throughout the study (0.42-0.02 log cfu/mL). Shell yeast and mold levels were significantly greater in free-range floor eggs than in free-range nest box eggs and conventional cage eggs throughout the entire study. Egg contents contamination levels were extremely low for all monitored populations and treatments. Season of the year played a role in both environmental and egg microbial levels. Winter had the lowest levels of all populations monitored for all treatments, except for aerobic free-range floor egg shell emulsions, which were increased (3.6 log cfu/mL). Understanding the differences in microbial populations present on conventional cage-produced and free range-produced eggs can lead to the development of effective cleaning procedures, enhancing food safety.