[Heterogeneous forms of prolactin in the blood and colostrum of ruminants]

The monomer form of prolactin prevailed in the blood of cows and she-goats in the physiological conditions associated with an intensive prolactin secretion. The dimer's content increased at the final stage of lactation and in pregnancy. High level of prolactin was found in the colostrum, a form of the prolactin with the milk mass over 100000 having been identified in the soluble fraction of milk. This particular form seems to appear directly in the mammal gland by means of binding of the monomer with an unknown protein.