The present study was designed to investigate and compare levels of estrogen and progesterone secreted into milk of crossbred heifers that were artificially induced into lactation with that of naturally calved cows. Group I animals comprised of ten crossbred Holstein Friesian cows which were in first lactation served as control. Twenty repeat breeding non-pregnant, non-lactating crossbred heifers with a history repeat breeding were divided into two equal groups (group II and III). Group II animals received two doses of PGF2α at 10 days apart (1st dose on day-10 and 2nd dose on day 0). In addition, these animals (group II) received 17β-estradiol (0.1 mg kg-1) and progesterone (0.25 mg kg-1) twice subcutaneously daily for 7 days (day 1 to 7). Metoclopramide (0.1 mg kg-1) and dexamethasone (20 mg animal-1) were administered for 4 days (day 14 to 17) by intramuscular route. Group III animals received 17β-estradiol (0.1 mg kg-1) and progesterone (0.25 mg kg-1) twice subcutaneously daily for 7 days (day 1 to 7) and metoclopramide (0.1 mg kg-1) and dexamethasone (20 mg animal-1) intramuscularly on day 14 to 17. Milking was initiated on day 19 in group II and III. The mean milk estrogen and progesterone concentrations were estimated during the 15 days in Holstein Friesian crossbred cows (n = 10) by radioimmunoassay. The mean milk estrogen concentration was significantly higher (p<0.05) in induced animals (group II and group III) on day 5 of lactation. From day 15 onwards, the milk estrogen concentrations did not differ significantly. Milk progesterone concentration significantly decreased (p<0.05) on day 1, 3, 11 and 13 in induced heifers (group II) as compared to normally calved cows. The concentrations of estrogen and progesterone in milk during the 15 days sampling period were comparable to those observed in normally lactating cows. This study suggested that estrogen and progesterone concentration of the induced milk was in similar pattern to that of normal lactating ani
