Diurnal variation of serum biochemical parameters in the Iranian fat-tailed sheep

In order to study the diurnal variation of serum biochemical parameters in the Iranian fat-tailed sheep, an experiment was conducted using five male adult Iranian fat-tailed sheep. Diurnal variation of serum biochemical parameters was determined by blood collections made every 2 h during 7 days of winter. Serum biochemical parameters measured were as follows: nonelectrolytes (total protein, albumin, glucose, cholesterol, triglyceride, creatinine, blood urea nitrogen), electrolytes (calcium, inorganic phosphorus, magnesium), enzymes (AST, ALT, ALP, LDH) and cortisol. In all, there was no significant difference in any of the serum biochemical parameters, except for cortisol concentration, which was highest in 0600–0800 hours. From 0600 to 0800 hours, serum cortisol concentrations were significantly higher than those observed from 12 noon. It is concluded that diurnal variation was only observed in serum cortisol concentration.