02056naa a2200241 a 450000100080000000500110000800800410001902400450006010000130010524501180011826000090023652013630024565000150160865000120162365000180163565000100165365000140166365000170167765000140169465300170170865300180172577300710174315308472023-09-01       1984    bl uuuu     u00u1 u    #d7 ahttps://doi.org/10.1079/BJN198400162DOI1 aHOVE, K.  aIntestinal radiocalcium absorption in the goatbmeasurement by a double-isotope technique.h[electronic resource]  c1984  aAbstract: Intestinal radiocalcium absorption was measured in goats by a double-isotope technique involving injection of 45CaCl2 intravenously and 47CaCl2 into the abomasum. Cumulative absorption of radiocalcium was calculated by deconvolution analysis form curves of plasma radioactivity. Repeated measurements at 2 d intervals gave highly reproducible results (r 0.94, P less than 0.001). No systematic difference between two consecutive measurements was observed. A good agreement between absorption of radiocalcium from simultaneously administered 47CaCl2 and 45Ca-labelled hay (r 0.93, P less than 0.001) seems to justify the use of inorganic 47Ca as a tracer for Ca in ruminant diets. Two- to three-fold increases in radiocalcium absorption 48 h after oral treatment with 1,25-dihydroxycholecalciferol or leaves of Solanum malacoxylon showed the usefulness of the method in situations of rapidly changing Ca absorption. Endogenous adaptations in intestinal radiocalcium absorption from 20 to 43% were observed in lactating goats when Ca intakes decreased from 12 to 4 g/d. It is concluded that the double-isotope technique is a suitable method for studies of Ca absorption in ruminants when tracer is introduced into the abomasum. The test is completed in 3-4 h and may therefore be used in situations where the absorption of Ca undergoes rapid changes.  aCalcitriol  aCalcium  aEndocrinology  aGoats  aLactation  aPharmacology  aPregnancy  aDrug effects  aRadioisotopes  tBritish Journal of Nutritiongv. 51, n. 1, p. 145-156, Jan., 1984.