Daily rhythms of serum and salivary parameters in goats

Abstract

Objective: Determine the daily rhythms of urea, bicarbonate, sodium, potassium, chloride, calcium, magnesium and inorganic phosphorus secretion in the serum and saliva of goats and whether there is a relationship between them.

Design: Ten non-gravid, non-lactating does underwent a 30-day preconditioning period (natural 24-h photoperiod, environmental temperature 19-21 degrees C, relative humidity 40-50%, the same feeding regimen, offered as a single meal at 07:00 hours, and water ad libitum), following which saliva and blood samples were collected from each subject every 4 h for 2 days (starting at 08:00 hours) for measurement of urea and electrolytes.

Results: Data analysis was conducted by one-way repeated measures analysis of variance (ANOVA) and by the single cosinor method. ANOVA showed a significant effect of time (0.001 < P < 0.01) on all the studied parameters in saliva and serum on both days. Cosinor analysis identified the periodic parameters and their acrophases (expressed in hours) during the 2 days of monitoring. Serum and salivary acrophases were all diurnal and were observed between 11:40 and 16:24 hours. No circadian rhythmicity was found for bicarbonate, magnesium or potassium in either saliva or serum.

Conclusion: There was a daily rhythm of secretion for the majority of the measured parameters, suggesting the potential role of saliva as an additional, reliable index for physiological, clinical, nutritional and chronophysiological studies.