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.
What is the use of vitamin a in the body? One of it's function is to help with the eyes. If you have bad night vision it is a sign of lack of vitamin A. If you don't get enough vitamin A you can go blind.