The word ᴱQ. poroke “barn fowl” appeared in the Qenya Lexicon of the 1910s, along with a second gloss “hen” that was deleted (QL/75). In Early Qenya Word-lists of the 1920s, Tolkien glossed ᴱQ. poroke as “hen” (PE16/132). In Common Eldarin: Noun Structure from the early 1950s, Tolkien had primitive words ✶porokĭ “fowl” and ✶porokē “hen” (PE21/82). Finally, primitive onomatopoetic roots √porok or √korok “hen” appeared in marginal notes from the late 1960s (VT47/36).
Neo-Quenya: Given the above, I would retain ᴺQ. porocë for purposes of Neo-Quenya, usable both for chickens in general as well as hens, much as the default gender of the English word “chicken” is female rather than male. For a specifically female chicken, however, I would use ᴺQ. holyë “hen”. The word porocë “fowl” might also apply to domesticated birds in general.
An onomatopoeic root appearing in notes from the late 1960s with variants porok- and korok and the gloss “hen” (VT47/36). It seems to be a restoration of the form ᴱQ. poroke “barn fowl” from the Qenya Lexicon of the 1910s (QL/75) with Gnomish cognate G. porog “fowl (domestic)” in the contemporaneous Gnomish Lexicon (GL/64). ᴱQ. poroke “hen” reappeared in Qenya Word-lists from the 1920s (PE16/132), and primitive ✶porokĭ “fowl” and ✶porokē “hen” appeared in Common Eldarin: Noun Structure from the early 1950s (PE21/82). Thus this root seems to be a pretty enduring notion.