A lactation length (LL) of 305 days in milk (DIM) does not fully represent the reality of milk yield and a great part of lactations extend beyond that period. This study aimed to compare the parameters of extended lactation curves with the traditional 305 DIM, considering parity orders (PO) in Holstein (HOL) and Jersey (JER) cows. Data were collected from 33,524 cows (31,194 HOL and 2,330 JER) across 544 dairy farms in Paraná, Brazil. Cows were classified by PO (primiparous, secundiparous, and multiparous) and LL, defined based on calving intervals of 11 to 13 months (LL305