Vitamin K1 & K2 have a critical effect on the function of osteocalcin, the bone protein that binds the mineral and protein in the bone together. Without sufficient Vitamin K the binding process is incomplete and low density or defective bone and cartilage are produced.

Vitamin K1 & K2 are naturally available in fresh, growing, green pasture but they are highly unstable, being degraded by UV light, wilting or “wintering off”. Horses that do not have constant access to high quality pasture are likely to be deficient in Vitamin K, leading to a reduction in bone density and strength.

Horses removed from Vitamin K rich pasture and brought into a box/yard regime have demonstrated a reduction in bone density within 7-10 days.

Side note: I use this on my personal horses. Even with full turn out and Alfalfa hay every year, this is the best winter coats they've ever had. 

*This is not a guarantee that YOU will see improvement, only a statement that*I* have