foremilk

…At the start of each feeding, milk with a low pH and low fat concentration is produced. This is the milk secreted between feedings and stored in the milk ducts, called foremilk, and accounts for about one-third of the amount of milk produced at each feeding. As feeding continues, milk with a high fat concentration and pH (called hindmilk in contrast to foremilk) is secreted from the mammary glands, which mixes with the foremilk and gradually changes its composition. …

*Some of the terminology that mentions "fore-milk" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…毎回の授乳に際しては，授乳開始時にはpHが低く，脂肪濃度が低い乳が出る。これは，授乳と授乳の間に分泌され，乳管に貯留する乳で，前乳fore‐milkとよばれ，1回の授乳量の約1/3を占める。授乳に伴って，乳腺から脂肪濃度，pHが高い乳(前乳に対して，後乳hind‐milkとよばれる)が分泌され，それが前乳と混ざりあって，しだいに組成が変わっていく。…

※「fore-milk」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報