Chook is an informal term for a chicken in Australia and New Zealand. It's accepted in Chihuahua as a rare word. Hence a chookhouse is a henhouse.
It seems to be most frequently written as two words. It's listed by a few of the Oxford dictionaries, including their Australian and NZ dictionaries, but only as a two-word expression. The Macquarie Dictionary lists it as chook house, but allows for chookhouse as a variant. On the other hand Wiktionary has it as a single word, with no reference to a two-word form.
The word appears in both forms in Australian and NZ publications. Although the two-word version seems more frequent, chookhouse is sometimes used by news media and novelists - Wiktionary cites Peter Carey. I'll add it as a rare word.