Verlauf von Vitamin-B₆-Gehalten wachsender Ratten bei Vitamin-B₆-freier Ernährung

This experiment was designed in two parts. In the first part the vitamin B₆ efficiency in response to increasing dietary vitamin B₆ intakes was tested in growing rats; in the second part the reaction of rats, originally supplied with the fourfold requirement and then switched on the vitamin-B₆-free basal diet was examined. The experimental animals were male Sprague-Dawley rats, of which weight gains, feed intake, and vitamin-B₆-concentrations in blood, liver and whole carcass were measured. At the beginning of the trial nine animals were analyzed; 54 additional animals, divided into six groups, were given a vitamin-B₆-free semisynthetic diet for three weeks which was supplemented with 0, 1.5, 3, 6, 12, and 24 mg vitamin B₆ per kg feed. For the second part the additional 54 animals were given a diet with 24 mg vitamin B₆ for three weeks and then switched to the vitamin-B₆-free basal diet. Six animals per group were sacrificed after 2, 5, 8,12,16, 20, 25, 30, and 35 days of depletion. Efficiency of dietary vitamin B₆ decreased from 38 % at 1.5 mg vitamin B₆ per kg diet to 4 % at the 24 mg dietary level. Also, without dietary vitamin B₆ the animals gained weight (from 145 to 300 g live weight), the daily feed intake increased from 14 to 19 g and feed efficiency decreased from 2.2 to 4.3 g feed per g gain. Vitamin B₆ concentration in tissues reacted differently. In blood after five days depletion no vitamin B₆ could be detected; in liver and whole carcass vitamin B₆ concentration decreased significantly in the first days and remained then at a level of 50 % of the starting concentration in the liver after five days and in the carcass after eight days of depletion. Whole liver vitamin B₆ content decreased significantly in the first five days from 60 to 43 Μg and then remained constantly, whereas whole carcass content of 245 Μg was not influenced significantly. It is concluded that in rats with a vitamin-B₆-free diet from day 10 to day 35, on the average a homeostatic level is maintained for the various vitamin B₆ contents.