The term 'breed of chicken' can be summarized by two crossword solutions: LEGHORN and CORNISH. LEGHORN is a breed of chicken originating from the Italian port city of Livorno, hence the name. It is a popular breed for egg production due to its high egg-laying capacity. CORNISH is a breed of chicken that originated in Cornwall, England. It is a dual-purpose breed, meaning it is suitable for both meat and egg production.