Effect of biotin supplementation on the vLa4 of thoroughbred horses

Thoroughbred horses in racing condition were supplemented twice daily with 25 mg biotin (biotin group), while control horses received an equivalent amount of maltodextrose as a placebo (placebo group). Changes of v_fLa4 (running speed necessary for producing a lactate concentration of 4 mmol/l in the blood) were determined with an incremental step test within three days and after two, three and four months after the beginning of supplementation. The mean v_fLa4 of both the biotin and the placebo groups (5 horses each) did not change significantly within three days of supplementation, but the mean plasma biotin concentration increased in the biotin group from 1.3±0.4 to 47±22 nmol/l (p<0.01), while remaining below 3 nmol/1 in the placebo group. There was no significantly different development of the v_fLa4 between groups over four months of supplementation. But, while the mean v_fLa4 of Thoroughbreds supplemented with biotin over this period of time did not show any changes, the v_fLa4 of the placebo group horses showed a tendency to decrease. In the biotin group, the mean plasma biotin levels varied between 38 and 64 nmol/l over the four months, while the biotin concentration of the placebo group never exceeded 3 nmol/1.