Ok-so I've been riding for 40 years, and teaching and training for 20. I have always based a horses' jump on his athletic abilities, scopiness, etc. I've seen the solid, 2'6 packers that can stretch to 3' but are better suited to the 2'6 job.
Bioactive vitamin D or calcitriol is a steroid hormone that has long been known for its important role in regulating body levels of calcium and phosphorus, and in mineralization of bone.
The basis of that study was that for those who take calcium, not only was Vitamin D necessary but in order to direct the calcium to where it is needed, one needed to take Vitamin K as well. That was the only reference to the importance of Vitamin K with calcium absorption until I came across this article.