EN
Lactation was studied in red deer Cervus elaphus Linnaeus, 1758 hinds from the Słowiński National Park during years 1990-1994. Yearling hinds did not participate in breeding. It was only 2.5 years old and older hinds that lactated. Lactation was prolonged until December and January when 52% of hinds were still lactating. Physical condition of hinds as measured with body weight, KFI, and visceral fat content did not differ significantly between lactating and not lactating hinds. The proportion of lactating hinds was declining until 1993 and increased in 1994. This was accompanied by a drop in the index of recruitment, ie the number of calves per 100 hinds.