Thursday, July 2, 2015

Dust-Bathing and Egg-Binding

It has rained here off and on for the past two weeks, but Saturday was gloriously sunny and warm, with a lovely breeze. I let the chickens out in the yard and gave their coop a thorough cleaning and drying--changing the bedding in the box, forking out all of the sodden straw in the coop and run, and letting everything dry out.

Meanwhile, the hens were having a wonderful time dust-bathing. Many animals, and particularly birds, practice dust-bathing--it enables them to clean themselves and prevents parasites. You've probably seen sparrows do this on a patch of bare ground. But chickens are the true artistes of dust-bathing.

First, they loosen the dirt by scratching it with their feet and raking it with their bills, making a little indentation in the ground. Then they stretch out and scratch with one foot while shaking the dust through their feathers.

They look pretty comical, but very happy.

I always feel like I'm seeing secret chicken behavior when I watch my hens dust-bathing. They are completely absorbed in the activity, seemingly oblivious to what is going on around them. Of course, any other time, they are hypervigilant, quick to react to a sound on the street, or to the shadow of a bird flying across the yard. Recently, I ran across an article about a research study which found that caged birds with no access to dust-bathing had higher levels of corticosterone, a stress hormone, than caged birds who were allowed to dust-bathe. Obviously, dust-bathing has some important physiological benefits for chickens that we don't fully understand--but they sure do.

The hens spent almost the whole day outside Saturday, and Sunday proved to be another non-rainy day, so I let them out again to roam the yard together. But looking out the window in the afternoon, I noticed Capitola, my beautiful Buckeye hen, off on her own, oddly stationary and tail drooping. She did not look at all well. My first thought was that she had an impacted crop. The crop is kind of an expandable storage compartment at the end of the chicken's esophagus, and it can sometimes get clogged up from too much vegetation. The birds had had a lot of time to graze the day before, and our grass was long and lush from all the rain, so it seemed right.

But Cap's crop didn't seem overly full, and as I examined her further, I began to worry that she was egg-bound. Egg binding, or dystocia,  is a common but serious and potentially fatal disorder that occurs in egg-laying birds and reptiles. The egg gets stuck in the oviduct on the way out--the hen stops eating, stops defecating, and will die in pretty short order unless the egg passes.

The problem is that hens are generally always working on producing the next egg. About every 25 hours or so, the hen releases a yolk into the funnel of her left oviduct (for some reason, the right one never develops). As the yolk travels through the oviduct, which is basically a long coiled tube, the membranes and egg white are added, and then it passes into the uterus, where the shell is added in layers. The hen lays the finished egg while the next egg is already in production.

The shell is made up almost entirely of calcium carbonate, so hens need a good source of calcium in their diet. Most layer feed contains calcium, but I also keep a supply of oyster shell in the coop for my hens just in case they need it. If they don't have enough calcium, their egg production slows down or they lay eggs with soft shells.

Capitola has always laid weird-looking, irregularly shaped eggs--hers is the pale oblong one on the far left, next to two normal-size brown eggs and a very tiny pullet egg from the other hens. She has also laid some real whoppers--eggs 1 1/2 times as big as the others' eggs--and in the past few weeks has laid some "rubber eggs" with very soft shells.

All of this probably puts her at greater risk for egg-binding than my other hens. I called my friend Debbie, who knows more about chickens than anyone else I know, and after I described Cap's symptoms and history, Debbie agreed that she was probably egg-bound.

Still on the phone, I picked Capitola up to get another look at her, and she dropped some yolk. While that meant that she was starting to pass the egg, a broken egg inside a hen is not really a good thing either--it can lead to infection or even internal injuries if the shell fragments are jagged. Debbie suggested I keep an eye on her in case she passed the egg, but cautioned not to wait too long to take her to the vet.

Fortunately, by late afternoon, Capitola began to walk around and ate a little bit of oyster shell and drank some water. She expelled more yolk and white, and by dusk was feeling well enough to eat some feed and scratch for worms near the compost pile. By Monday morning she was back to her old self, the first one to march down the ramp to get some chow.

Here's hoping Cap's future eggs arrive with a little less anxiety for all of us.

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