Naked Science Forum
Life Sciences => Plant Sciences, Zoology & Evolution => Topic started by: Liz Amoore on 14/11/2010 16:30:03
-
Liz Amoore asked the Naked Scientists:
Why do chickens excrete only poos and not poos and wees?
Question from my class as they have watched our chickens hatch!
What do you think?
-
Chickens and other birds and reptiles concentrate their nitrogen wastes into uric acid instead of urine. This takes more energy, but conserves water.
-
They do urinate, actually!
If you look closely (but not too closely) at a chicken's dropping, you should see that it is made up of three parts. All three parts are usually passed in one go after they are stored together in the cloaca.
The 'poo' bit is a brownish to greenish colour, depending on what you are feeding the chickens. The surrounding white bit is the uric acid part, as JH mentioned. It is made by the liver and is not soluble in water. It supposedly serves two main purposes. It requires less water to excrete than the water-soluble version, urea, that mammals make. Change in its colour can be a sign of disease. The third part is urine. It might be a little less obvious to see, but if you find a dropping on newspaper, you should see it as the watery "wet bit" around other 2 parts.
Hope that helps! It's so nice to see animals being part of the classroom again! When kids grow up with no idea where their food is coming from, or become overcome with fear or aggression - we've got something to be ashamed of... Just make sure they wash their hands afterwards! :)
-
http://en.wikipedia.org/wiki/Cloaca
http://en.wikipedia.org/wiki/Uric_acid#Biology
-
Great question.. and I spent my whole young life raising chickens with my family and never ever noticed that at all, to even ask The question! Thank you all for your answers.. I have learned something new and that is very cool!
-
Wonderful answer, SquarishTriangle - thank you!
Chris