Pestilence profile: MG (Mycoplasma gallisepticum)


Mycoplasmas have a “fried egg” appearance under a microscope. Photo credit: E. Arum and N. Jacobs

Mycoplasms have a “fried egg” appearance under a microscope. Photo credit: E. Arum and N. Jacobs

Mycoplasma organisms such as MG are weird. Science fiction writers hope for the creativity to come up with a villain and plot as creepy and strange as these organisms and their life cycles. Mycoplasms are among the simplest life forms on the planet, yet they are responsible for serious diseases of birds, people, cattle, and other creatures.

Mycoplasms are incredibly tiny, even by bacterial standards, and they lack a cell wall that nearly all bacteria have. This is both an advantage and a disadvantage, because although it makes them resistant to some types of antibiotics that target a bacterial cell wall, it also makes them very fragile, so that they do not survive long outside of a host animal. We can use this to our advantage, by avoiding the types of antibiotics that mycoplasms ‘laugh at’, such as penicillin, and by cleaning and resting our chicken coops for about two weeks between groups of birds, allowing the organisms in the environment to die out before reintroducing new birds.

Because MG causes serious economic losses (fewer eggs and slower growth, for examples) in commercial poultry farming, many of the world’s nations, including the U.S., have agreed to report MG infections to the World Organization for Animal Health (OIE) and to work toward controlling the disease. MG infection is a reportable disease in many U.S. states; this means that if an MG infection is detected in a backyard flock, depending on the state in which the flock is located, animal health officials might be required to investigate and/or quarantine the farm. Unfortunately, the most effective way to successfully eliminate MG infection and lift the quarantine is to destroy all of the birds, clean and disinfect the premises, and start over.

Next: Eradicate, control, or live with it?

Chronic respiratory disease and MG: What’s it good for? Nothing.

Swollen sinuses are common in turkeys with MG infection, but not seen in chickens very often. Photo courtesy of Cornell University

Swollen sinuses are common in turkeys with MG infection, but this sign is not seen in MG infected chickens very often. Photo courtesy of Cornell University. Visit

‘Chronic’ respiratory diseases in chickens are illnesses that go on for months or for the lifetime of the bird. Typically, chickens with disease of the upper respiratory system will make unusual sounds: ‘snicking’, sneezing, or rales (wet, rattling or crackling noises while breathing). Discharge with a consistency ranging from thin and frothy to thick and sticky might be seen coming from the eyes, nostrils, or mouth. The eyelids or face might swell, indicating conjunctivitis or inflamed sinuses. Affected birds are often depressed and lose weight. If the lower respiratory tract (lungs and air sacs) is affected, the bird often shows difficulty in breathing, or may simply be found dead without obvious previous signs of illness.

No single culprit is responsible for all of these miserable sick chickens; there are quite a few different common and important causes of poultry respiratory illnesses. One major offender is the bacteria Mycoplasma gallisepticum (also known as MG). Chronic Respiratory Disease (CRD — or what I prefer to call “CRuD”, and others call “colds” or “roup”) caused by Mycoplasma gallisepticum is a common and frustrating disease of backyard poultry.  Let’s focus on MG.

Many species of birds can be affected by MG, including chickens, turkeys, game birds such as pheasants and peafowl, and songbirds. The disease caused by MG can be found worldwide. In the U.S., the disease has been eradicated from most commercial chicken and turkey breeding farms.

You may have heard backyard poultry owners say, ‘Just about everyone’s got MG’. Although that statement is probably an exaggeration, poultry experts think MG infection is common in small, non-commercial flocks in the U.S., but we don’t have a reliable estimate of the number of infected backyard flocks across the U.S. One survey of California backyard flocks in the 1980s found that 38% of flocks tested positive for MG.

Mycoplasma gallisepticum is transmitted by close contact between birds, or by birds coming in contact with things contaminated with MG, such as cages, feeders, or waterers. It can also pass from an infected hen to her chicks though the egg. Transmission through the air is possible, but only over very short distances.  Birds infected with MG remain infected for life, although they may never show signs of disease, or show illness only during stressful periods, such as showing or shipping. Because infected birds might not look sick, it is possible for poultry owners to be unaware that they’ve introduced the infection into their flock, for example, with that bird from the auction or the batch of hatching eggs from Ebay.

Next time: What to do about CRuD?

I quail every time I check the brooder

Quail: So tiny, so adorable, and so good at finding creative ways to leave this world. Every few hours, I look in on my bobwhite hatchlings, expecting the worst. Despite the marbles in the shallow dish, allowing the diminutive galliforms to sip the microliters of water between the spheres, they drown themselves in the waterer. Somehow, they find tiny gaps in the brooder walls, and quickly succumb to hypothermia. They must have magical abilities, because I haven’t found an opening that would allow a paper clip to pass through. Another steep poultry-raising learning curve. Have you tried quail?

On self-destruct mode?

On self-destruct mode?

Robert Frost, poultryman

Today, to mark the 50th anniversary of Robert Frost’s death, a collection of letters, photos, recordings, and other memorabilia goes on display at the University of Buffalo. I’d like to see that collection, because I am a fan of his work – his poetry, of course, but especially his essays about his career as a poultry fancier. I wonder if that facet of his life can be glimpsed in the new exhibition.

Yes, Robert Frost was as obsessed with the poultry fancy as you or me, but much more eloquent. Before he became famous as a poet, he made a few bucks writing prose for New England poultry journals; a fact that probably didn’t come up in your English classes. You can read a collection of these little-known musings about chicken keeping in Robert Frost: Farm-Poultryman, edited by Edward Connery Lathem and Lawrence Thompson, published by Stinehour Press in 1963. If you know your chickens and chicken show people, you’ll be amused and certain you’ve met some of his characters. Don’t bother sharing with your chickenless friends at your book club, however; they won’t get it.

I declare that the best chicken poem ever written is Frost’s A Blue Ribbon at Amesbury. If you meditate by gazing at your flock (I can’t be the only one), you’ll certainly feel a flood of empathy for this flock keeper’s pride, worries, and joys centering on his prize pullet.

The one who gave her ankle-band,
Her keeper, empty pail in hand,
He lingers too, averse to slight
His chores for all the wintry night.

I must not slight my chores, so I bid you good night.

Got cold feet?

Magpie duck warming her toes

Magpie duck warming her toes

Wicked cold spell here. That’s relative, right? If you’re keeping poultry in negative double digit temperatures, you’ll think our North Carolina winters — with occasional days dipping just below freezing — are balmy. My birds have never had to deal with conditions under 20 degrees F (about -7 degrees C), but their cold-weather behaviors kick in just like birds in more northerly flocks who really have it tough.

Bundle up, and go outside to watch your poultry’s thermal management skills. Their cold-adaptive behaviors are interesting when you realize what they’re doing and why. Among my menagerie of poultry, I think my ducks have the most remarkable feet and foot-warming behaviors, so I’ll give them the spotlight in this post.

A lot of a bird’s body heat is lost through non-feathered skin, particularly feet in contact with cold ground or water. Brrrr. Chickens will stand shifting their weight from one leg to the other, tucking the non-weight bearing leg up into their insulating abdominal fluff. Ducks will do that too, when it’s simply chilly out, but in sub-freezing temperatures, they’ll lie down on their bellies, tucking both feet up to warm them in their downy under parts. I’ve seen my ducks slide across snow on their fronts, penguin-style, minimizing foot contact time with the frozen stuff.

Look at all that surface area of those webbed duck feet – an engineer would call them very effective heat sinks.  That’s a good thing in hot weather; duck bodies cool off very effectively in hot weather by increasing circulation to heat-dissipating feet. The opposite happens in cold weather – a duck’s blood vessels restrict blood flow to the legs and feet, sending just enough blood to keep tissues from freezing.

The energy cost of keeping duck feet from freezing is high when environmental temperatures go sub-zero. When it’s between 32 and 68 degrees F (0 to 20 degrees C) outside, ducks lose about 5% of the body heat they produce through their feet. Below freezing, that energy cost nearly quadruples; ducks lose almost 20% of the total body heat they produce through their feet.  What does that mean to a duck keeper in winter? Your ducks will be hungry and your feed bill will go up!

Not as lazy as your dog

Delaware rooster and hen
Backyard chickens have weighty responsibilities and busy lives. Not only are they constantly facing the hazard of appearing delicious to a large segment of the animal kingdom, but many chickens are also expected to contribute to household economy and nutrition with daily gifts of eggs, at the same time they’re playing the role of lovable family pets. Do we expect so much from any other animal companion?