DIETARY THIAMIN SUPPLY DURING LACTATION INFLUENCES THIAMIN STATUS IN LACTATING RATS AND THEIR OFFSPRING AND THE THIAMIN LEVEL IN MILK

This study was conducted to examine the effect of dietary thiamin, ran ging from deficient to excessive supplies, on thiamin status of lactat ing rats and their offspring, and the thiamin level in milk. Therefore , after parturition, rat darns were divided into eight groups of 10 ea ch, and were fed diets with 0, 2, 4, 6, 7, 40, 350 and 3 500 mg/kg thi amin over a total of 13 days during lactation. Milk for determining th e thiamin concentration was obtained from day 6 and 13 of lactation. A t day 14 of lactation rat dams and their offspring were used to ascert ain the thiamin status including transketolase activity of blood, live r and brain, and thiamin concentration in body. Thiamin supplies rangi ng from deficient to excessive dietary concentrations influenced both the thiamin levels of the lactating dams and their offspring within 13 days. Lactating rat dams fed a thiamin-free diet and their offspring were classified as thiamin-deficient on the basis of growth retardatio n and a lower activity of transketolase in blood, liver and brain. Wit hin these variables transketolase in blood has been shown to be most s ensitive, and reached a plateau feeding 6 mg/kg thiamin. The concentra tion of thiamin in milk ranged between 0.1 and 19 mg/kg. The findings also show that dietary thiamin had the strongest effect on thiamin in milk obtained from day 6 and 13 of lactation, and a deficient or subop timal supply with thiamin was therefore not compensated for an intensi fied transfer of reserved body thiamin into milk. Also thiamin levels in tissues and carcass, which did not show any clear-cut saturation ch aracteristic, increased with increasing dietary thiamin, and this dose -dependence was more marked in blood and liver than in carcass.