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.
Vitamin D is important for the absorption of calcium from the stomach and for proper functioning of calcium in the body. The Recommended Dietary Allowance (RDA) for vitamin D is currently 400 IU for patients between 50 and 70 years of age.