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.
A constant supply of calcium is necessary throughout our lifetime, but is especially important during phases of growth, pregnancy and lactation (breast feeding). About 10-40% of dietary calcium is absorbed in the small intestine (Somer, 1995; Mahan et al, 1996). The level of calcium absorption from dietary sources drops in post-menopausal women. The body will absorb more calcium if there is a deficiency. Factors that improve calcium absorption include adequate amounts of protein, magnesium, phosphorous and Vitamin D. Conditions that reduce calcium absorption