发情期 refers specifically to the period when animals are in heat (estrus) and are receptive to mating. Although the dictionary gloss includes 'puberty', that sense is rare and can be misleading — for human puberty the standard term is 青春期 (qīngchūn qī). This word is a compound of 发情 ('to be in heat') and 期 ('period'), so it is used almost exclusively for animals.