In 3 trials, the effects of dietary supplementation with phytase (PHY) and 25-hydroxycholecalciferol on BW and the blood characteristics of commercial layers that were inoculated prelay (12 wk of age) or at the onset of lay (22 wk of age) with F-strain Mycoplasma gallisepticum were assessed at 34, 50, and 58 wk of age. Experimental layer diets, which included either a basal control diet or the ...

The plasma concentration of 25-hydroxycholecalciferol was measured in 13 adult Hermann's tortoises (Testudo hermanni), seven adult spur-thighed tortoises (Testudo graeca) and two adult marginated tortoises (Testudo marginata) during 2004. They were healthy, of both sexes, and kept in captivity under natural unfiltered sunlight in southern England with no dietary sources of cholecalciferol. Bloo...

The metabolism of vitamin D(3) has been studied after intravenous injection of 10 IU of [1,2-(3)H]-vitamin D(3) to vitamin D-deficient rats. The disappearance of the radioactivity from the plasma follows a very peculiar pattern characterized by an early rapid disappearance followed by a rebound of radioactivity before assuming still a third rather slow disappearance rate. The "rebound" phenomen...

It has been previously established that vitamin DB (cholecalciferol) must undergo an obligatory two step metabolism to first 25hydroxycholecalciferol and then 1,25-dihydroxycholecalciferol prior to the initiation in the intestine of increased calcium transport. These steps are mediated successively by the liver and the kidney. The present report compares the time course of appearance of vitamin...

It has been previously established that vitamin DB (cholecalciferol) must undergo an obligatory two step metabolism to first 25hydroxycholecalciferol and then 1,25-dihydroxycholecalciferol prior to the initiation in the intestine of increased calcium transport. These steps are mediated successively by the liver and the kidney. The present report compares the time course of appearance of vitamin...

1. A radioimmunoassay of 25,26-dihydroxycholecalciferol has been developed with an antiserum raised in a sheep, tritiated 1,25-dihydroxycholecalciferol as tracer and synthetic 25,26-dihydroxycholecalciferol as standard. The metabolite was purified from serum extracts by Sephadex LH 20 and high-pressure liquid chromatography; recovery was monitored with biologically generated, tritiated 25,26-di...

The effects of dietary supplementation with phytase and 25-hydroxycholecalciferol on the performance characteristics of commercial layers that were inoculated prelay (12 wk of age) or at the onset of lay (22 wk of age) with F-strain Mycoplasma gallisepticum were assessed. Experimental layer diets, which included a basal control diet or the same diet supplemented with 0.025% phytase and 25-hydro...