What Eggs are Safest?

I work in the professional egg world.  I know by name the vast majority of people who supervise the production, transport, grading, marketing and delivery of the eggs you find in your grocery stores, restaurants, farmers markets (yes, legally, those eggs need to be professionally graded too), and industrial users of eggs (think bread, cake, cookie, cereal, etc. makers).  I know how much care, concern, time, money and worry is dedicated to preserving the safety of eggs.  Being a vet, I am very involved in advising on many aspects of egg safety, right from chicken health to giving opinions on egg handling, and even national programs for salmonella control.

We, in the world of Canadian large-scale egg production, are quite proud of our safety record, and the programs we have in place.  We often debate whether small producers (read backyarders and hobby farmers) can produce a product that is comparable in safety.  We snicker a little at activists that say we need to get away from large-scale farming, since you can produce healthier eggs in your backyard, or on your apartment house roof.  How on earth can removing the expertise and care that we provide result in a healthier product?  By concentrating the number of birds on a farm, you allow a person to focus strictly on the care and protection of the hens….learn about them and become truly an expert.  I admit to having this opinion much of the time.

Many, many people disagree though.  “Factory farms”, “industrial production”, “bacterial breeding grounds” have been used to describe professional farms….unfairly, I think, but the terms are sincerely used by many people.  The problem is that there are many confounding factors.  Depending on what you WANT to read in a paper, almost any study can say anything.  Professional, caged farms are much bigger than extensive farms, and exponentially bigger than recreational farms.  If there is 1 contaminated egg per 1000 in a cage barn, the farm will produce many contaminated eggs per day.  A backyard flock with a rate of 1 contaminated egg per hundred would only have 1 contaminated egg per month.  If you eat 2 eggs per day, however, which is safer? 

The fact remains (check any activist website for examples) that many studies show that large farms have higher bacterial contamination.   Conversely (check any egg farming website for examples) many studies show that professional farms are much safer, contamination wise.  So, what’s right?

There is a very recent scientific paper from Spain that describes bacterial contamination that I think is quite balanced.  It must be taken with a grain of salt, however, since in North America, all graded eggs are washed, whereas in the EU, this is not the case.  Also, the rules on antibiotic use is different.   That being said, the study found that there was more significantly more bacterial contamination in free-range, organic and backyard (called “domestic eggs”) production than in free run (birds free inside of a barn), while cage barns had the least contamination.

Having said that, the authors went on to evaluate the antibiotic resistance in the different systems.  Free run barns were worst, then cage barns, then free range (outside), organic and backyard flocks had the least antibiotic resistance.  Both these findings make sense to me.  Large scale farms have a higher tendency to use antibiotics (thus the resistance), whereas backyard flocks almost never medicate (sometimes that is itself a problem). 

Which is more important?  I don’t know.  Antibiotic resistance doesn’t necessarily mean that the bacteria is likely to make you sick…it just means that if you treat an infection, you are more likely to clear it.  Some resistant bacteria don’t make you sick at all….some susceptible bacteria make you deathly ill, very quickly.  On the other hand, if you DO get sick from a resistant bacteria, it can be a serious problem. 

Bottom line, eggs from backyard flocks are more likely to be contaminated by bacteria than anything you would buy in a grocery store.  Be careful with them….wash your hands; keep the eggs in the fridge, separate from other foods; rinse eggs in running water to remove contamination before packing them in the fridge……and then relax.  Contamination rates are very low, and most bacteria are not pathogenic.  Take reasonable precautions and then just enjoy the fruits of your labours.  You are as likely to give yourself an ulcer from stressing about the bacteria as you are of getting food poisoning.

Mike the Chicken Vet


12 responses to “What Eggs are Safest?

  1. This is great Mike! As a city chickener I have to think about all these things! Thanks to you, I know what to do.

    Also the new coop came, and it is great. Too bad, we can’t post pictures in the comments section.

    You are truly amazing for doing this, and I appreciate it so much.

    I know you spoke to Matthew on the phone (I was too hysterical), and you really calmed us down. With no parents at home, it was just and we really did our best.


    PS. Do you think she was in pain from the Mareks? She was so healthy one day, and the next…

  2. poultrymatters

    It is interesting to read that perspective. I have never had concerns about either ‘domestic’ or shop eggs. Neither, to my knowledge, have ever made me or my family sick. I think the secret to enjoying domestic eggs is to have clean nests and eat the eggs fresh. They taste better that way. I know there’s bacteria all over the eggs but if it doesn’t make me sick it doesn’t worry me. I’ve been eating home grown eggs for 30 years and while I had a bout of food poisoning from KFC, I’ve never had any ill effect from an egg. I never wet my eggs. If an egg is soiled I throw it out. Rightly or wrongly, I’ve been told that wetting the egg reduces the storage potential. I assume the belief is that the moisture will take external bacteria through the pores. What do you think the benefit of rinsing them is?

    • By rinsing the eggs, you will “flush” a large percentage of the bacteria off the shell….if it is running water, and will take the bacteria away….do not dip or soak fresh eggs in standing water, since you will just make bacteria “soup”, which will cross contaminate the eggs. Always use cold water to rinse the eggs, so the interior of the egg doesn’t heat up…if it does, when it cools and contracts, you can suck bacteria through the pores into the interior of the egg. What you are thinking of regarding storage potential is if you remove the fatty cuticle that covers the egg. Usually water will not do this, as long as you do not use a detergent or soap.
      Hope this helps.


  3. Rinsing eggs will help loosen any soil or bacteria from the surface. The issue is taking them from the fridge, and then rinsing them which may create small cracks and allow any bacteria to get into the egg, possibly without you seeing the cracks. This is why egg farms have their coolers set at 10-13 and not 4 degrees like other foods should be stored at. Too cold followed by a warm rinse will crack them.

    So if you do rinse, do it before you refrigerate. The benefit would be that there is less bacteria on the shell for cross contamination to happen. Last thing you want is to touch the shell, covered in salmonella, and then eat the perfectly fine egg, but the toast you touched gets contaminated by the Salmonella and you get sick.


  4. HI Mike,

    I was just wondering, do you think my other hens (who had been vaccinated) could have shed the disease to “Honey”, and thats how she died?

    I was reading about this, and I am just wondering.


    • That is quite likely what happened Andrew. Mareks is a herpes virus, and it will stay with the chickens for life….if they get stressed, they will often shed the virus into the environment. If “honey” was not protected, she would likely have picked up the live virus from the coop and gotten sick from the disease the clinically healthy hens shed.


  5. Matthew Patel

    Hi Mike,

    All of our chickens are roosting with their legs straight. Not all at the same time, but we see all of them doing it. Normally they bend their knees and cover up their legs with their feathers, but now they are not. Do you know why?


  6. Matthew;
    It’s a temperature thing…..chickens don’t sweat, so deal with heat by panting and increasing conductive heat loss….by exposing their legs to the air, they help keep themselves cooler.


  7. Matthew Patel


  8. Do guineas ever calm down?

    • Hi Nancy;

      Although it may not seem like it, almost all flocks of hens will calm down as they age. The more time you spend with them, and the more they get used to you and their surroundings, the more they will settle in. The bad news is that guineas are not as domesticated as some of the other hens out there, and one of the major effects of domestication is to decrease the amount of fear and flightiness an animal (or chicken) displays. Soooo….good news and bad…they will improve, but it won’t be quick, and may never get to the point where you would describe them as “quiet”.


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