Factors affecting urinary pyridinoline and deoxypyridinoline excretion in the growing lamb

Changes in urinary pyridinium crosslink excretion and plasma osteocalcin and growth hormone levels were measured at 3-5 week intervals in lambs from 2-22 weeks of age, in relation to changes in metatarsal length. There were close correlations between pyridinium crosslink excretion and plasma growth hormone levels and live weight gain, but no direct relationship was seen between the rates of excretion of the pyridinium crosslinks and linear bone growth. Plasma osteocalcin levels were correlated with linear bone growth rate up to about 12 weeks of age but, thereafter, showed no correlation despite a continued decline in bone growth rate. In the young lamb, daily pyridinium crosslink excretion represented 1.3-2.9% of that in the body, declining to 0.06% of pool size in adult sheep.