Studies on the transfer of plasma iron to milk in the lactating rat

The transfer of an intravenous does of 59Fe from plasma to milk in the lactating rat was a rapid process which accelerated exponentially with time until a plateau was reached 2 to 4 hours after injection. This transfer of iron involved little participation of the iron in the mammary gland pool. Also, neither the lactoferrin of the milk whey nor the iron-carrier molecule of the casein played a specific role in the iron transfer process. The present results show that the total percentage of plasma 59Fe transferred to the milk and sucklings in the lactating rat is much more than those values reported in lactating rabbits (Tarvydas, Jordan and Morgan, 1968) and sows (Hansard, 1965).