The effects of dietary cholecalciferol steroids and gonadal hormone implantation on plasma 1,25-dihydroxycholecalciferol and bone calcification in preovulatory and senescent female Japanese quail

Using preovulatory Japanese quail hens (28d), one of two forms of vitamin D 3, cholecalciferol (CC) or the analog 1α-hydroxycholecalciferol (1α-OH-CC), was fed in combination with silastic implant treatments of 17β-estradiol benzoate, and/or testosterone propionate, and/or sham implants in a 2×2×2 factorial arrangement. The 5 μg/kg dietary level of 1α-OH-CC maintained plasma levels of 1,25-dihydroxycholecalciferol (1,25-(OH) 2CC) on an equal basis with a 20 μg/kg level of CC (800 I.U., 2×requirement level). Testosterone treatment caused a significant depression in plasma 1,25-(OH) 2CC, while 17β-estradiol (E 2) had no significant effect. Treatment with E 2 resulted in a marked increase in plasma calcium and the total calcium, % calcium, and medullary bone contents of the femur. In a second experiment, a population of 130 wk old Japanese quail hens were used in a 3×2 factorial design to test for the main effects of dietary vitamin D source (CC, 1α-OH-CC or 1,25-(OH) 2CC) and E 2 implantation on similar plasma and bone parameters. Again, significant stimulatory effects of E 2 treatment were observed upon most bone calcification measurements, and total bone calcium (P