There are limited scientific studies on egg washing methods for eggs from free-range flocks to reduce the risk of foodborne illness. Current recommendations from the Centers for Disease Control are for poultry owners not to wash eggs because improper washing and drying (water less than 95℉ or moisture not removed) can increase the risk of contamination by trans-shell passage of bacteria through shell pores (personal communication with Dr. Megin Nichols, CDC scientist). For this project, I am hypothesizing that specific management practices will reduce the amount of dirt/manure on eggs including frequency of egg collection, type of nest box, location of nest box and nest materials will reduce manure/dirt on eggs while reducing shell bacteria levels.
I will determine if maintaining the egg cuticle on “clean” eggs may also provide protection from bacteria in eggs from free-range hens and eliminate the need and cost of egg washing by small-scale poultry producers. By identifying best poultry management and egg handling practices for free-range hens, this project will directly contribute to the sustainability of local agriculture by reducing the health risks of foodborne illness and potentially reducing costs associated with egg handling for sale to improve the quality of life of the farmers and the farm community.
The research will be conducted on the University of Rhode Island’s Peckham Farm which houses the food animals used in teaching and research on campus. We will be pasture-raising 50-60 laying hens (Barred Rock, Buff Orpington, Red sex-liked, White Leghorn, RI Red) using a mobile chicken tractor. For each experiment, eggs will be collected from the pasture-raised flock each morning and bacterial sampling conducted within 3 hours of collection. Experiments will be run in triplicate (on three different days with the same environment conditions). This work will take place in collaboration with the Sartini lab that is testing different egg washing/sanitation and handling methods commonly used by poultry owners for bacteria levels and cuticle thickness. I will do this work in collaboration with the Sartini lab that has an available Incredible Egg Washer and ISP-REF integrated sphere spectrophotometer for measuring the egg cuticle.
Objective 1: Determine management practices to reduce manure on eggs from pasture-raised hens
1A. Does frequency of egg collection (1 vs 2 times per day) reduce dirt/manure and bacteria levels? I hypothesize that eggs that are collected once daily sit in a nest box for most of the day and are open to further contamination from other hens sitting and standing on the eggs along with other environmental factors. Increasing the number of times eggs are collected each day could lead to less contamination from other hens and lower bacterial levels.
1B. Does nest box type (conventional wall-mounted vs roll-away) reduce dirt/ manure and bacteria on eggs? In the roll-away boxes, after the egg is laid, the egg rolls forward into a separate compartment because the nest floor is slanted. The conventional wall mounted boxes hold the egg on the nest material in the box after the egg is laid until the egg is collected. The conventional boxes allow other hens to walk and sit on already laid eggs which can lead to contamination and increased manure/dirt on the eggshell. I hypothesize that eggs collected and tested from roll away boxes will have lower bacterial counts and be visibly cleaner compared to the conventional nest box type.
1C. Does nest box location (mounted 18” high or on ground ) reduce dirt/ manure and bacteria on eggs? I hypothesize that nest boxes at floor level will have eggs that are dirtier and carry higher bacterial counts from hens being able to freely walk and hang out in the nesting boxes vs having to jump up and perch to get to higher mounted boxes.
1D. Does nest box material (plastic mat vs straw vs shavings) reduce dirt/ manure and bacteria on eggs? Hay and shavings are the nesting materials most commonly used among farmers and poultry owners (URI Egg Survey) but retain manure and could increase dirty eggs. I hypothesize that nest boxes lined with a plastic mat will produce cleaner eggs with lowered bacterial counts when compared to eggs collected from boxes with hay or shavings.
Objective 2: Comparison of cuticle, bacteria and egg quality measurements on clean (no dirt/manure) washed and unwashed eggs. I will test the hypothesis that the range of bacteria levels will be the same on clean eggs (obtained through best management practices) and washed eggs but the egg cuticle will be removed after washing.
The purpose of this project is to identify best management practices that will result in clean eggs (no manure/dirt) and determine if the egg cuticle helps to maintain protection from bacteria to develop safe egg handling guidelines for small-scale free-range poultry producers. I will also determine if maintaining the egg cuticle on level 1 (clean) unwashed eggs will also provide protection from bacteria in eggs from free-range hens and eliminate the need of egg washing for small-scale poultry producers. By testing the research objectives, the best management practices for keeping eggs “clean” or at a low bacterial level will be discovered. These management practices will contribute to food safety and efficiency for small-scale producers in the Northeast SARE region.
We plan on starting to collect data and running trials this spring through early fall when egg production is the highest.