Progress report for GNE19-192
Because of the 50 by 60 initiated in New England, there has been a push for locally sourced, sustainable food. New England only has about 5% of its land currently producing food. The New England Food Vision proposes changes in local food production so that there is 15% land usage for agricultural purposes (Donahue et al, 2014). Smaller-scale egg production is a growing industry in Rhode Island along with the ownership of backyard chickens. Because eggs and other poultry products are a popular food source, accessibility to local and safe products is important to consumers in Rhode Island and all of New England. Many local farms have adopted free-range production where the poultry is allowed access to pasture or the outdoors.
Foodborne illness risk exists from small-scale free-range eggs due to lack of guidelines for safe egg handling, lack of salmonella testing of hens and management practices that promote dirt/manure on eggs from free-range hens. 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). The egg cuticle is a protective (glycoprotein and antimicrobial) coat that covers the egg during oviposition and can protect the egg from E. Coli and Salmonella typhimurium penetration (Bain et al., 2019). Recent research has shown that manure removal leads to similar bacteria levels of washed and unwashed eggs with the cuticle maintained (Hannah et al., 2011).
Our team at the University of Rhode Island and the University of Connecticut are conducting a survey of backyard and small-scale poultry producers (URI Egg Handling Survey opened April 2019; URI IRB approval) to obtain information about the prevalence of egg-laying hens in the NE SARE region and common egg handling practices. Preliminary survey data as of May 6, 2019 (117 respondents; range of flock size 4-230 chickens; from Rhode Island, Massachusetts, Vermont, New Hampshire, Connecticut, Pennsylvania) demonstrates that a wide variety of egg washing methods and management practices are used among small-scale poultry producers. Only 44% of poultry owners state that they are always washing the eggs before consumption, while 55% reported that they sometimes or never wash their eggs. Additionally, 86% of respondents reported that they wash their eggs using a water temperature less than 90℉ (this is less than the industry standard of 95℉ and increases the risk of internal bacterial contamination of the egg). Most producers never test for salmonella (89% of respondents). These results demonstrate that safe egg handling practices are unclear among poultry owners increasing the risk of transmission of foodborne illness. A variety of poultry management methods are also reported in the survey including different nest box materials (73% used wood boxes, 18% metal nest boxes, 4% rollaway boxes or 5% don’t use nest boxes). Nest materials used include shavings (58%), straw (32%) and plastic mats (4%). Eggs are collected most often once a day (55%) while 25% of respondents collect eggs twice a day.
Preliminary data collected has shown that there is a significant difference in bacterial load on the eggshell in washed (bucket washed) vs unwashed eggs (Craig et al., 2019). There was also a varying degree of total bacterial load on unwashed eggs depending on the level of soiling on the eggshell. An increasing correlation between level of soiling on the shell and average bacterial load on the shell was observed. An experiment of bucket washed vs dry washed eggs was also conducted where the average total bacteria count was compared. Bucket washed eggs had lower bacterial load on average when compared to “dry” or “dry sponge” method of washing without water or detergents used.
I have hypothesized 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.
- Objective 1A: Does nest box type (conventional wall-mounted vs roll-away) reduce dirt/ manure and bacteria on eggs? Eggs will be collected once daily (8am) first from both the conventional wall-mounted nest boxes and roll away boxes.
Objective 1B: Does frequency of egg collection (1 vs 2 times per day) reduce dirt/manure and bacteria levels? Eggs will be collected either once daily (8am) or (12pm) or twice daily (8AM and 12PM) from rollaway and conventional nest boxes.
Objective 1C: Does nest box (conventional) location (mounted 18” high or on ground ) reduce dirt/ manure and bacteria on eggs? Comparison of egg cleanliness and bacterial count on eggshell from eggs collected from the 10-hole nest box mounted at 18 inches in the coop vs eggs collected from nest boxes at the coop floor level. For this experiment only the conventional nest box will be tested- rollaway nest boxes removed from the coop.
Objective 1D: Does nest box material (plastic mat vs straw vs shavings) reduce dirt/manure and bacteria on eggs? Hay and shavings material will be placed in each of the mounted conventional nesting boxes. Plastic mats are commonly used in metal and roll away nest boxes to minimize manure contamination from organic nest box materials. Comparison will include straw (control) vs shavings, comparison of straw (control) vs plastic nest pad, rollaway week 1- plastic nest pad substrate and rollaway week 2- no substrate.
Objective 1E: Is there a preference for rollaway vs conventional mounted nest boxes and nesting material? During objective 1A and 1D data will be collected on preference of type of nest box and nesting material used in the boxes.
Objective 2: Comparison of cuticle on clean (no dirt/manure) washed and unwashed eggs.
There are no evidence-based guidelines on the proper management, washing, handling of eggs collected from pasture-raised small-scale poultry farms which could contribute to food safety risks for farmers and consumers involved in local food production. The purpose of this project is to identify the best management practices, including frequency of egg collection, type of nest box, location of nest box and nest materials, that will result in consistent cleanliness of eggs (no manure/dirt) with decreased bacterial load on the eggshell to develop safe handling guidelines for small-scale free-range poultry producers in the area. In this study, new information will be generated on best practices for management and egg handling for free-range hens to develop guidelines to support the sustainability of local egg production.
- (Educator and Researcher)
This research was conducted on the University of Rhode Island’s Peckham Farm which houses the food animals used in teaching and research on campus. We are currently pasture-raising 53 laying hens (Barred Rock, Buff Orpington, Red sex-liked, RI Red, White Leghorn, Easter Egger) using a mobile chicken tractor.
For each experiment, eggs were collected from the pasture-raised flock at the same time of day and bacterial sampling conducted within 3 hours of collection. The chicken tractor was moved daily to provide birds with fresh forage and the coop floor scraped every morning to ensure cleanliness of the inside of the coop. Nesting materials used in the conventional style boxes were straw and changed out weekly. Rollaway boxes were lined with the astroturf nest pads and cleaned weekly.
- Objective 1A: Does nest box type (conventional wall-mounted vs roll-away) reduce dirt/ manure and bacteria on eggs? Eggs were collected once daily first from both the conventional wall-mounted nest boxes and roll away boxes. Both conventional and rollaway boxes were used simultaneously throughout this experiment, except for the last week of collection in August where only the rollaway was available to the hens. 12-15 eggs were collected on three separate days throughout each week. Data was collected from May 18th – August 25th. Both box types were mounted at 16-18 inches in the coop. Straw was used as the substrate in conventional boxes and astroturf nest pad in rollaway box and both were completely cleaned out once weekly. After eggs were collected daily at the same time (approx. 8am-9am), they were inspected for cleanliness level (Egg Dirt/Manure Chart below). Once the eggs have been inspected and ranked on cleanliness, a sample for total bacteria was taken with Microsnap test swabs.
Objective 1B: Does frequency of egg collection (1 vs 2 times per day) reduce dirt/manure and bacteria levels? Eggs were collected either once in the am (~8am), once in the afternoon (~1pm) or twice daily (8AM and 12PM) daily from rollaway and conventional nest boxes with 12 eggs collected per day for three consecutive days (36 eggs per treatment; 144 eggs total). This experiment was conducted between June 29th and July 16th. Straw substrate was used in conventional wall mounted and astroturf plastic mat in the rollaway nest boxes and the substrate was cleaned weekly. When eggs were collected daily, they were inspected for cleanliness level (Egg Dirt/Manure Chart below). Once the eggs have been inspected and ranked on cleanliness, a sample for total bacteria was taken with Microsnap test devices.
Objective 1C: Does nest box (conventional) location (mounted 18” high or on ground ) reduce dirt/ manure and bacteria on eggs? For each location, at least 12 eggs were collected on three separate days. The same flock was used (location of conventional next boxes moved after all eggs had been collected). When the eggs were collected daily, they were inspected for cleanliness level (Egg Dirt/Manure Chart below) then a sample for total bacteria was taken. Comparison of egg cleanliness and bacterial count on eggshell from eggs collected from the 10-hole nest box mounted at 18 inches in the coop vs eggs collected from nest boxes at the coop floor level. For this experiment only the conventional nest box was tested- rollaway nest boxes were removed from the coop prior to the beginning of this experiment. Week 1– Nest box mounted at 18 in on wall of coop. Week 2– Nest box at floor level (bottom row of conventional 10 hole and conventional 2 hole boxes mounted around floor level in back of coop.
Objective 1D: Does nest box material (plastic mat vs straw vs shavings) reduce dirt/manure and bacteria on eggs? Hay and shavings material were placed in each of the mounted conventional nesting boxes. Plastic mats are commonly used in metal and roll away nest boxes to minimize manure contamination from organic nest box materials. This comparison included straw (control) vs shavings, comparison of straw (control) vs plastic nest pad, rollaway week 1- plastic nest pad substrate and rollaway week 2- no substrate. The standard time of collection and cleaning schedule was the same as previous experiments. For each bedding type, 12-20 eggs were collected on three separate days (167 eggs total). When the eggs are collected daily, they were inspected for cleanliness level (Egg Dirt/Manure Chart below) then a sample for total bacteria was taken with Microsnap test devices.
Objective 1E: Is there a preference for rollaway vs conventional mounted nest boxes and nesting material? During objective 1A and 1D data was collected on preference of type of nest box and nesting material used in the boxes. The amount of eggs collected from each nesting box (either rollaway or conventional) was recorded each day. This data will be used to determine if there is a preference in the nest box based on use by the chickens. Number of eggs collected from each nest box (conventional only) with different nest substrates will be recorded and used to determine if there is a trend in which substrate material (straw/shaving/AstroTurf mat) is most desirable for the hen while laying.
Objective 2: Comparison of cuticle egg parameters on clean (no dirt/manure) washed and unwashed eggs. After completion of Objective 1, I will determine the best management combination of practices (frequency of egg collection, nest box location, nest box type and nest box materials) for collection of eggs that are free from manure and dirt. Six eggs were collected in level 1-2 range on the Egg Cleanliness Sheet periodically between August 6th and September 18th. Three of the eggs were washed according to the URI egg washing protocol (water at 100-105 F for 10 minutes with Egg Wash Powder, rinse) in Incredible Egg Washer ™) and the other 3 eggs left unwashed. After the washed eggs were done drying, three equidistant measurements were taken along the eggs equator with the Minolta Colorimeter. The eggs were then dyed according to the Sartini Cuticle Deposition protocol and three more equidistant measurements were taken along the eggs equator after eggs were dyed. An equation (provided by Dr. Ian Dunn) was used to calculate the Delta E value of each egg. This number was able to show the change in cuticle thickness on the eggshell between the washed and unwashed eggs.
All data collection for objectives 1a-1e will be completed during the peak laying period (25-40 weeks), which is between the dates of May 8th- August 27th. The coop floor will be scraped daily every morning and the nest box substrate cleaned out weekly and replaced.
Bacteria level quantification: Egg bacterial levels will be measured initially using the MicroSnap Total Viable Count bioluminogenic test (Weber Scientific).
I am in the process of analyzing the results for this project.
This project has helped to fund another project that was built on the research and justification from this SARE grant. The Sartini Lab has received funding from NIFA grant for the project titled, “Developing Evidence Based Handling Guidelines for Improving the Safety of Free-Range Poultry Eggs“. The summary and aims of this project are as follows:
We propose to conduct pilot studies to develop evidence-based and cost-effective egg handling guidelines and educational materials for small-scale egg producers in our region.
The aims of this proposal are:
1) Determine the prevalence of Salmonella in chicken eggs from small-scale farms in Rhode Island and Connecticut.
2) Determine the efficacy of common egg washing methods to reduce total bacterial load and Salmonella on eggs and
3) Develop outreach and educational programs to train the farmers in proper egg handling and food safety and disseminate results of the research.