Serum concentration of calcium, phosphate and 1,25-dihydroxyvitamin D3 in goat (Capra hyrcus): Daily rhythms

Abstract

The goal of the present study was to investigate the daily rhythms of calcium, phosphate and 1,25-dihydroxyvitamin D3 (1,25-(OH)2 D3) in the blood serum of goats. Blood samples from six Girgentana breed goats were collected via an intravenous cannula inserted into the jugular vein at four-hour intervals over a 48-hour period (starting at 08:00 hours on day 1 and finishing at 04:00 on day 2). The serum concentration of calcium and phosphate was measured by photometric test and of 1,25-(OH)2 D3 by HPLC. All parameters were expressed as mean ± SEM. The one-way repeated measures analysis of variance (ANOVA) was used to determine significant differences. ANOVA showed a highly significant effect of time in all the parameters studied. The application of the periodic model and the statistical analysis of the Cosinor enabled us to define the periodic parameters and their acrophases (expressed in hours) during the 2 days of monitoring: all the studied parameters exhibited diurnal acrophases, which were within 12:44 and 17:28 hours. The results obtained led us to reveal the existence of a daily rhythm for the parameters considered and their temporal physiological values are useful for their implications in the formulation of therapeutic and nutritional protocols in the goat.