Effects of vitamin B-6 deficiency during lactation on the vitamin B-6 content of milk, liver and muscle of rats.

Effects of a dietary deficiency of vitamin B-6 imposed during the lactation period on the level of this vitamin in milk, liver and muscle were assessed in rats. A control diet (vitamin B-6 free basal diet supplemented with 10 mg pyridoxine . HCl/kg) was fed to all rats just before and during the gestation period. On day 1 of lactation, dams were randomly assigned to three dietary treatment groups: deficient (vitamin B-6 free basal diet), control or restricted control (control diet restricted in quantity to that consumed by the deficient group). Levels of total vitamin B-6 in milk, liver and muscle were determined by microbiological assay on days 1, 6, 16 and 21 of lactation. On day 6, the concentration of vitamin B-6 in milk of deficient dams was less than 20% of control or restricted control values. The low level of vitamin B-6 in milk of the deficient group continued to be evident on days 16 and 21 whereas in control and restricted control groups the vitamin content increased on days 16 and 21 compared to the values on day 6. In contrast to the low level of vitamin B-6 content observed in milk on day 6 in the deficient group, the vitamin content in liver of this group was approximately 75% of control or restricted control values, and the vitamin content in muscle was not significantly altered by the deficiency. Hence, milk was effected sooner by the deficiency and was an earlier indicator of impending vitamin B-6 deficiency than was liver or muscle tissues.