The March to Cage-Free and Free-Range Eggs: Are They Safe and Nutritious?

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The March to Cage-Free and Free-Range Eggs: Are They Safe and Nutritious? | Dr. Jean Dodds

Approximately 200 companies have pledged to only sell, or use in their products, cage-free eggs. These companies are not just your local food cooperative or all-natural specialty grocery stores like Whole Foods. We are talking about huge, conventional and mainstream companies ranging from McDonald’s to Royal Caribbean Cruise Lines.

This sea change is attributed primarily to the activities of animal rights activists who drove the consumer market to demand more humane farming practices, as well as the avian bird flu crisis of 2015. Currently, sales of cage-free and free-range eggs are stable or slightly decreased at the grocery store, but that has not detracted companies from their pledge. Even top mayonnaise-producing companies are now touting the use of cage-free eggs.

As expected, critics state a variety of concerns about cage-free and free-range practices such as: a). are less humane due to cannibalism and other behaviors; b). are costly to farmers; and, c). may increase the potential for diseases that arise in such environments due to substandard management-related health issues.

Indeed, John Brunquell, President and Founder of Egg Innovations (the largest free-range operation in the United States), admits he had to climb a steep learning curve to overcome these challenges when he was transitioning his farm from conventional cages. He also acknowledges there will be cases when “management is not up to par.” Yet, he was successful and now his flock can engage in normal chicken behaviors such as dust-bathing and perching. Bravo!  

Nevertheless, we see these as growing pains and hope that the cage-free and free-range industry will prevail. We must remember that all farming operations are susceptible to diseases including the avian bird flu outbreak in 2015 that overwhelmed many conventional cage farming operations. As well, research studies are being conducted to aid the transition process and combat diseases as much as possible. 

For instance, a study published in 2011 indicated that diatomaceous earth had reduced the internal parasite loads in two different breeds of organically raised free-range layer hens. This study was mentioned in the mainstream egg industry press.

We have read through dozens of articles on the subject of free-range, cage-free and conventional cage systems. Most of them did not perform proper experimental comparisons between conventional cage laying hens and cage-free / free-range productions. In some comparisons, biases were clearly focused to prove a particular side’s position. 

While we do prefer cage-free and free-range eggs as benefitting the welfare of these animals, we still see bias being presented. Therefore, we decided to focus here on the safety and nutrition side of the topic, and to highlight two comparative, unbiased studies.

Study 1: Comparison of shell bacteria from unwashed and washed table eggs harvested from caged laying hens and cage-free floor-housed laying hens

Egg shells can harbor bacteria such as Escherichia, Micrococcus, Salmonella, Streptococcus and Staphylococcus spp. The environment in which eggs are laid impacts the amount of bacteria, as well as the wash type and wash method used.

This experiment had three parts to it, included both brown and white egg-laying hens, and compared unwashed to washed egg bacterial contamination levels.

Part 1 – Hens were separated and placed in the 3 housing systems: conventional cages, elevated wire slats (mimicking cage-free), and all new pine shavings-covered concrete floors (free range). Nest boxes with rubber finger nest pads were provided for hens housed on wire slats and shavings. Perches were also placed in the wire slats and shavings pens.

Part 2 – The hens were then moved into triple-deck battery cage units and placed 2 hens/cage (1 white laying egg and 1 brown egg hen/cage). This type of system housed hens in cages with mechanized manure removal belts.

Part 3 – Hens were placed in their original environment in Part 1. It must be noted that none of the environments were cleaned.

Part 2 of the experiment proved to have the least amount of bacterial contamination for unwashed eggs. The manure removal belts significantly decreased the incidence of contamination compared to Parts 1 and 3. However, washing the eggs did further reduce the amount of bacteria.

The primary difference between Parts 1 and 3 of the experiment is the method of washing and the solution used. In Part 1, the eggs were spray-washed together in a single batch using a commercial egg-washing solution. The egg washing method and solution in Parts 2 and 3 used a small-scale egg-washing unit and a chlorine-free egg washing powder. In essence, the Part 1 eggs rotated in place while receiving a constant spray pattern. Whereas for Parts 2 and 3, the eggs rotated while proceeding down the conveyer to receive a varied sanitizing spray pattern.

The results indicated that the rinse method and solution in Part 1 reduced bacterial load counts from 3-4.2 across all egg environments and colors of eggs to 1.3- 2.2, statistically.

For Part 2, the washing was negligible as the load counts went from 0.6-1.0 unwashed to 0.0-0.3.

Remember that in Part 3, the environment was the same as Part 1 but the rinse solution and method was the same as Part 2. The results are very interesting. The bacterial loads went from 2.8-3.8 for the unwashed eggs down to 0.4-0.8 for the washed eggs.  

Thus, the results indicate that egg shell bacterial levels are similar after washing eggs from hens housed in caged or in cage-free environments.

Study 2: Comparison of fatty acid, cholesterol, and vitamin A and E composition in eggs from hens housed in conventional cage and free-range production facilities

441 Hy-Line Brown pullets (young hens) were reared in accordance with the laying environment of range or cage. The dietary program was the same for all stages of life for each group. The only difference here was access to the range paddock for the free-range hens, which had a hay mixture of Bermuda grass, fescue mix and clover. The researchers minimized the variables between the two groups as much as possible. Additionally, they sent samples to four different laboratories for analysis.

The laboratories reported varied results amongst one another, which had a significant effect on the levels of saturated fatty acids, monounsaturated fatty acids and beta-carotene.

Regardless, the study authors were able to draw some interesting conclusions.

  • Eggs from the range production environment had more total fat, monounsaturated fat and polyunsaturated fat than eggs produced by caged hens.
  • Levels of omega-3 fatty acids were also higher: 84.5 mg/50 g in the eggs from the range hens compared with 70.50 mg/50 g in the eggs from the caged hens.
  • The range environment had no effect on cholesterol.
  • Vitamin A and E levels were not affected.

The researchers found the higher fat content in the eggs from free-range hens than those of caged hens of note. Even though the feeds were consistent between both groups, the logical suppositions included forage consumption, an increased intake of wild seeds or insects
associated with the environment, or both, among the free-range hens.

Although, vitamins A and E were not influenced by housing type, beta-carotene levels were higher in the eggs from the free-range hens. Higher beta- carotene levels in the free-range eggs may have contributed to the apparent darker yolks, but this was not measured. Even though the range environment did not contribute a change in the vitamin A and E content, the increased beta-carotene likely would have resulted in increases in lycopene, lutein or zeaxanthin (carotenoid pigments help protect eyes from macular degeneration and perhaps the progression of cataracts in elderly people and pets). However, they were not measured in this study.

As you can see, more research needs to be done, but these results are promising.

W. Jean Dodds, DVM
Hemopet / NutriScan
11561 Salinaz Avenue
Garden Grove, CA 92843


Anderson, K.E. “Comparison of fatty acid, cholesterol, and vitamin A and E composition in eggs from hens housed in conventional cage and range production facilities”. Poultry Science, Volume 90, Issue 7, 1 July 2011, Pages 1600–1608,

Bennett, D.C. “Effect of diatomaceous earth on parasite load, egg production, and egg quality of free-range organic laying hens”. Poultry Science, Volume 90, Issue 7, 1 July 2011, Pages 1416–1426,

Brulliard, Karin. “Many People Think a Cage-Free Life Is Better for Hens. It’s Not That Simple.” The Washington Post, WP Company, 15 June 2017,

Dreyer, Jerry. “Disease Challenges of Cage-Free Environments.” Egg Industry, Mar. 2018,

Hannah, J.F. et al. “Comparison of shell bacteria from unwashed and washed table eggs harvested from caged laying hens and cage-free floor-housed laying hens”. Poultry Science, Volume 90, Issue 7, 1 July 2011, Pages 1586–1593,

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