Thyroxine and insulin-like growth factor-I in milk and plasma of camels (Camelus dromedarius)

To study the pattern of insulin-like growth factor-I (IGF-I) and thyroxine (T4) levels in four lactating camels and their newborns, by radioimmunoassay. Milk and blood samples were taken at parturition, and on the 1st, 2nd, 3rd, 7th, 14th, and 21st day after parturition Milk IGF-I levels were high at parturition and decreased with stages of lactation, whereas T4 levels were low at delivery and progressively increased after. T4 levels in calves, were 4-5 times higher than those of their dams at birth, then declined thereafter but remained almost twice those in dams on day 21. In newborn calves, IGF-I levels were significantly lower at birth compared to those of dams, and gradually increased with age until reached the same values of those in dams on day 21. These profiles were similar to those reported in domestic ruminants, and might be considered as preliminary data for dynamic studies of bone metabolism in camels.