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http://www.geocities.com/ostrichwonderland/characteristic.htm says a female ostrich is a hen.
www.emusupply.com/basic_habits.htm    says a female emu is a hen.  

What we call ""chicken eggs"" are actualy fowl    eggs. What we call chicken (for eating) is the meat (or whole body) of young fowl.
Any of various birds of the order Galliformes. The common, widely domesticated chook , Gallus gallus, are in the category of  fowl. SO if you really want to refer to the common chicken stock, you might say ""Gallus Gallus"", or perhaps the breed of gallus gallus as per http://www.ithaca.edu/staff/jhenderson/chooks/chooks.html ... there are a lot of breeds ! )  "