Comparison of shell bacteria from unwashed and washed table eggs harvested from caged laying hens and cage-free floor-housed laying hens

Department of Poultry Science, The University of Georgia, Athens, GA, USA.
Poultry Science (Impact Factor: 1.67). 07/2011; 90(7):1586-93. DOI: 10.3382/ps.2010-01115
Source: PubMed


These studies evaluated the bacterial level of unwashed and washed shell eggs from caged and cage-free laying hens. Hy-Line W-36 White and Hy-Line Brown laying hens were housed on all wire slats or all shavings floor systems. On the sampling days for experiments 1, 2, and 3, 20 eggs were collected from each pen for bacterial analyses. Ten of the eggs collected from each pen were washed for 1 min with a commercial egg-washing solution, whereas the remaining 10 eggs were unwashed before sampling the eggshell and shell membranes for aerobic bacteria and coliforms (experiment 1 only). In experiment 1, the aerobic plate counts (APC) of unwashed eggs produced in the shavings, slats, and caged-housing systems were 4.0, 3.6, and 3.1 log(10) cfu/mL of rinsate, respectively. Washing eggs significantly (P < 0.05) reduced APC by 1.6 log(10) cfu/mL and reduced the prevalence of coliforms by 12%. In experiment 2, unwashed eggs produced by hens in triple-deck cages from 57 to 62 wk (previously housed on shavings, slats, and cages) did not differ, with APC ranging from 0.6 to 0.8 log(10) cfu/mL. Washing eggs continued to significantly reduce APC to below 0.2 log(10) cfu/mL. In experiment 3, the APC for unwashed eggs were within 0.4 log below the APC attained for unwashed eggs in experiment 1, although hen density was 28% of that used in experiment 1. Washing eggs further lowered the APC to 0.4 to 0.7 log(10) cfu/mL, a 2.7-log reduction. These results indicate that shell bacterial levels are similar after washing for eggs from hens housed in these caged and cage-free environments. However, housing hens in cages with manure removal belts resulted in lower APC for both unwashed and washed eggs (compared with eggs from hens housed in a room with shavings, slats, and cages).

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Available from: Nelson Anthony Cox, Nov 16, 2015
    • "Raised cages improve production by reducing disease risks to the birds while, at the same time, facilitating egg collection (ADAS, 2005). In addition, data from chicken studies indicate that eggs laid in raised cages have a lower aerobic bacterial load than eggs laid in litter (Hannah et al., 2011), resulting in increased hatchability, chick growth and quality (Scott and Swetnam, 1993) and decreased embryo and chick mortality (Reid et al., 1961). Nevertheless, concern has been raised over the ethics of confining semi-wild birds in barren cages as gamebirds are deliberately bred to retain their semi-wild behaviour which may be related to flying characteristics (FAWC, 2008) and are released back into the wild after the breeding season. "
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    ABSTRACT: Each year, the UK rears around 20–30 million pheasants and 3–6 million red-legged partridges for shooting purposes. However, welfare organisations and some members of the gamebird industry itself have raised concerns about the use of raised laying units for breeding gamebirds. Although the proportion of breeding gamebirds kept in raised systems is relatively low there is some evidence that numbers may be increasing yet the incidence and severity of the challenges to gamebird welfare when housed in raised cages has never previously been assessed. Concern has also been raised over the ethics of confining semi-wild birds in barren cages as gamebirds are deliberately bred to retain their semi-wild behaviour which may be related to flying characteristics. The Farm Animal Welfare Committee and some sections of the gamebird industry have voiced concerns that such systems are incompatible with their ethical values, suggesting that the welfare of gamebirds in cages justifies rigorous assessment.
    Applied Animal Behaviour Science 05/2015; 165:17-24. DOI:10.1016/j.applanim.2015.02.001 · 1.69 Impact Factor
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    • "Some of the factors presented include the differences in European and US hen management practices, hen genetics, and climate. Scientists in the United States have also been investigating the effects of housing systems on egg safety and hen health (Hannah et al., 2011; Jones et al., 2011, 2012; Gast et al., 2013, 2014; Jones and Anderson, 2013). Each study compares different housing systems under controlled research conditions, thus allowing for clear comparisons. "
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    ABSTRACT: Hen housing for commercial egg production continues to be a societal and regulatory concern. Controlled studies have examined various aspects of egg safety, but a comprehensive assessment of commercial hen housing systems in the US has not been conducted. The current study is part of a holistic, multidisciplinary comparison of the diverse aspects of commercial conventional cage, enriched colony cage, and cage-free aviary housing systems and focuses on environmental and egg microbiology. Environmental swabs and eggshell pools were collected from all housing systems during 4 production periods. Total aerobes and coliforms were enumerated, and the prevalence of Salmonella and Campylobacter spp. was determined. Environmental aerobic and coliform counts were highest for aviary drag swabs (7.5 and 4.0 log cfu/mL, respectively) and enriched colony cage scratch pad swabs (6.8 and 3.8 log cfu/mL, respectively). Aviary floor and system wire shell pools had the greatest levels of aerobic contamination for all eggshell pools (4.9 and 4.1 log cfu/mL, respectively). Hens from all housing systems were shedding Salmonella spp. (89-100% of manure belt scraper blade swabs). The dry belt litter removal processes for all housing systems appear to affect Campylobacter spp. detection (0-41% of manure belt scraper blade swabs) considering detection of Campylobacter spp. was much higher for other environmental samples. Aviary forage area drag swabs were 100% contaminated with Campylobacter spp., whereas enriched colony cage scratch pads had a 93% positive rate. There were no differences in pathogen detection in the shell pools from the 3 housing systems. Results indicate egg safety is enhanced when hens in alternative housing systems use nest boxes. Additionally, current outcomes indicate the use of scratch pads in hen housing systems needs to be more thoroughly investigated for effects on hen health and egg safety. © 2014 Poultry Science Association Inc.
    Poultry Science 12/2014; 94(3). DOI:10.3382/ps/peu010 · 1.67 Impact Factor
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    • "Hannah i wsp. [5] wskazują, że niepoddane myciu skorupy jaj od niosek z chowu klatkowego charakteryzowały się obecnością większej liczby bakterii tlenowych niż jaja z chowu na ściółce z wiórów drzewnych. Po umyciu jaj liczba bakterii na ich skorupie nie była czynnikiem różnicującym systemy chowu. "
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    ABSTRACT: Summary The objective of the research study was to assess the changes in selected quality traits of hen eggs after washing their shells and with focus on the storage time. The research material consisted of eggs produced by Hy-Line Brown laying hens during the 33rd week of their life. The birds were reared in one building and had access to green runs. Based on the shell cleanness criterion, the eggs were divided into 2 groups of 540 eggs each. Group I was a control group, the eggs in Group II were washed in water of 300C for 3 min. All the eggs, stored under a temperature of 15-18 ºC and a humidity of 50-70 %, were weighed on the day of laying and, next, on the 7th, 14th, 21st, and 28th day. The depth of air in the storing place was determined on the day when the eggs were weighed. On the 1st and the 28th day, 120 eggs were taken to assess the quality of their content. The traits of egg shells were assessed (crushing strength, weight, thickness, density) as were the traits of albumen (weight, height, pH) and yolk (colour, weight, pH). The majority of egg traits analysed changed during storage. The washing of egg shells had no effect on the egg weight loss during storage. The washing diversified the depth of air cell, the thickness and strength of shell, and, slightly, the weight and content of yolk, as well as the number of Haugh units after 28 days. The results obtained prove that the ban on washing eggs from Class A, substantiated by the drop in their quality traits, seems to be unjustified.
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