EFFECT OF VARYING DIETARY VITAMIN-B-6 SUP PLY ON CONCENTRATION OF PYRIDOXINE, PYRIDOXAL AND PYRIDOXAMINE IN BLOOD AND MILK OF LACTATING RATS

A total of 80 female Sprague-Dawley rats weighing 260 g were fed a sem isynthetic diet containing 5 mg vitamin B-6/kg diet after mating. On d ay 1 post partum, the rats were distributed into 10 vitamin-B-6 treatm ent groups (0, 3, 6, 9, 12, 15, 18, 36, 360 and 3 600 mg/kg diet). On days 7 and 13 of lactation, the darns were milked, killed by decapitat ion on day 14. Pyridoxine, pyridoxal and pyridoxamine were analysed by HPLC. The results showed a linear increase in vitamin B-6 concentrati on in blood in response to alimentary vitamin-B-6 supply. In terms of a physiological vitamin B-6 supply, the total vitamin content in blood consisted of 96% pyridoxal and 4% pyridoxamin, respectively. High-dos e supplies of more than 360 mg/kg diet caused the appearance of pyrido xine in the blood. Concentration in milk showed a quadratic increase i n vitamin B-6 in response to dietary vitamin-B-6 supply. The total vit amin-B-6 in milk consisted of 80% pyridoxal, 10% pyridoxamin and 10% p yridoxine. Between day 7 and day 13 of lactation, total vitamin concen tration in milk increased by about 21%. These results indicate a close correlation between the dietary vitamin-B-6 supply and the concentrat ions in blood and milk. It was concluded chat the maternal organism re gulates vitamin-B-6 concentration in milk homeostatically, which also resulted in higher values during later lactation to meet the requireme nts of the litter. The necessity of a sufficient dietary vitamin B-6 s upply is presented.