Galactopoiesis refers to the physiological maintenance of lactation once milk secretion has been established. In dairy cows, milk yield follows a characteristic bell-shaped lactation curve, rising steadily to a peak at 4–6 weeks postpartum and then declining gradually until drying off before the next calving. The lactation period is commonly categorized into early (14–100 days), mid (100–200 days), and late (200–305 days) stages, with peak yield typically occurring during 5–6 weeks of lactation. During early lactation, cows experience a marked negative energy balance because nutrients are preferentially directed toward milk synthesis, but this imbalance generally resolves by 5–7 weeks postpartum. The shape and persistency of the lactation curve are primarily determined by the number and activity of mammary secretory cells. Maintenance of milk production is governed by several endocrine and metabolic regulators, including prolactin, somatotropin, glucocorticoids, and thyroid hormones, which support milk component synthesis and effective gland emptying. Milk yield and composition remain highly dynamic traits influenced by genetic factors such as breed and parity, as well as environmental and managerial conditions, including nutrition, milking frequency, and climate.