The nutritional thiamin status of lactating rats and thiamin transfer into milk and offspring

This study was conducted to determine whether moderate alterations in dietary thiamin concentrations during lactation would influence the body thiamin of lactating rats, and the transfer of thiamin into milk and to their offspring within a short time of 6 and 13 days. Therefore, after parturiton, rat dams were divided into 6 groups of 8 each, and were fed diets during lactation with 0.5, 6, 9, 12, 24 and 36 mg/kg thiamin over a total of 13 days. Milk was analysed for its thiamin concentration at day 6 and 13 of lactation. Thiamin status including transketolase activity in blood and erythrocytes, and thiamin concentration in blood, liver and carcass were measured at day 14 of lactation both from the rat dams and their 13-days old pups. Rats receiving 0.5 mg/kg thiamin in their diet were classified as thiamin-deficient on the basis of reduced body weight, and transketolase activity in blood and erythrocytes. The thiamin requirement during lactation can therefore be assessed at 6-9 mg/kg. Thiamin concentration in milk ranged between 0.2 and 5.6 mg/kg, and was influenced strongly by the dietary thiamin supply. Also, the body thiamin concentration of the offspring also reflected strongly the dams' dietary intake, and the thiamin in milk, respectively. If the tissues are listed in order of their dose-dependence, a sequence was obtained in which blood was followed by the liver and carcass. However, in all cases, thiamin concentration in the body defined no clear-cut saturation characteristic.