Abstract
The dietary need for supplementary vitamin K3 (sodium menaphthone bisulphite) was determined in weanling male rats of two hysterectomy-derived strains fed on Spillers Laboratory Small Animal Diet (autoclaved). The basal diet had 0.6 ppm of added vitamin K3 to which further supplements of either 0, 4, 16 or 64 ppm vitamin K3 were added. There was a significant difference between strains in body-weight gain (P<0.001) but not in plasma prothrombin time. After 14 weeks the mean plasma prothrombin time of rats receiving the basal diet was higher (P<0.01) than the mean of those receiving the supplemented diets; but the three supplemented diets did not differ significantly.