T.J. Fischer, A.J/ Cawdell-Smoth. A.M. Talbot H.L. Regtop, J.R. Biffin, and W.L. Bryden University of Queensland, Equine Research Unit, School of Agriculture and Food Sciences, A Agricure PTY Ltd., Bracmar NSW, 2576, Australia
The role of vitamin K in blood coagulation has been known for many decades, but in recent years it has shown to be a factor in many other physiological processes. Studies in human and rodents have heightened the role of vitamin K, and its dependent proteins, in bone metabolism, energy utilization and immunity. Placental transfer of vitamin K is limited in the human, and there has been no research conducted on horses on this aspect of vitamin K metabolism or transfer of the vitamin into milk. The objective of this study was to determine if vitamin K crosses the equine placenta, and if the concentration of the vitamin in mare’s milk can be modulated by dietary supplementation.
Eighteen late gestation mares were allocated to three treatment groups. These treatments consistent for a control (no vitamin K administration), Vitamin K3 (menadione) and vitamin KQ (Quinaquone™ a soluble form of K1 and K2 (10:1)). The vitamin treatments were administered as a 4mg oral bolus paste to each horse, 3 times per week (Monday, Wednesday and Friday), until parturition.
Administration of the paste commenced 28 days before the due foaling date. Blood sampling of the mares was undertaken weekly up to foaling, at parturition and 7 days later. Blood sampling of the foals and milk collection from the mares were performed simultaneously prior to first suckle by the mare, 12hrs, 34hrs and 7 days post birth. Plasma samples for each treatment along with the milk samples were analyzed by HPLC for vitamin K concentrations.
No differences in circulating concentrations of vitamin K were found in mares irrespective of supplementation group. However, milk concentrations at parturition reflected supplementation with KQ mares having a significantly (p<0.05) higher value than the other two groups. Values for both supplemented groups returned to control levels within 7 days of cessation of supplementation. The failure to detect differences in circulating levels in mares prior to foaling may reflect the time of sample collection as previous studies found that the half-life of vitamin K is rapid. Plasma K2
