Comparative production of beta-lactoglobulin and orotic acid with lactose in bovine mammary cell cultures: effects of cell density and constituent inhibition.

Abilities to accumulate beta-lactoglobulin and ortic acid were compared to lactose in dispersed cell cultures of lactating bovine mammary tissue. The inverse of the amount accumulated of each milk constituent at a given time in the culture medium was a linear function of the inverse of the cell density. The amount of lactose had no effect on its own subsequent accumulation, but added orotic acid and beta-lactoglobulin inhibited their own production. The accumulation of certain milk constituents in the culture medium is a factor in the expression and loss of normal function in the in vitro cultures which may be related to the observed effects of milk accumulation in vivo on the rate of milk synthesis and mammary involution.