They are having contractions to push the egg out.
efferent and afferent neurons
Chickens lay eggs.
Because inside the duck the fat doesn't help release the eggs from the body...
Your body's temperature set point has been raised so that your body will heat up in order to help your immune system destroy the pathogens that are inside you.
When chickens are genetically altered to have larger breasts their legs cannot support their body weight. The chicken can usually walk no more than a few steps before laying down.
I've been a beekeeper for many years and I've never heard of this happening.
your uterus lining is breaking down because no embryo (fertilised egg) has needed it. it comes out the body as blood.
Skin and feathers.
You can stimulate egg laying by increasing the day length with lighting, and by keeping your coop at a higher temperature in winter. If you are getting 3 or more eggs per week per chicken, that is about all you can expect. In Northern Canada, my chickens pretty much quit laying in November and then start back to laying in late February. This is because of the shorter day light and colder temperatures. (They live in an insulated coop but they keep the coop at about freezing with their body heat.)
The chickens were possibly killed by a fox or other predator.
Sven Allan Svensson has written: 'Observations on calcium secretion in hen's egg-shells and on body composition and phosphate metabolism in growing chicks and laying hens' -- subject(s): Chickens, Feeding and feeds
you can get blood clots