CIRCADIAN-TIME DEPENDENCE OF PLASMA NON-ESTERIFIED FATTY ACID, GLUCOSE, AND α-AMINO NITROGEN VARIATIONS IN MITHUN (BOS FRONTALIS) COWS

Abstract

Metabolite transport through the plasma is an essential part of normal life, and regulation of the plasma metabolite concentration is a part of the normal pattern of metabolic regulation during feeding and fasting. Wide variation of circulating metabolites may reflect ruminant efficiency and energy status in ruminants. In the present experiments, plasma contents of α-amino nitrogen (AAN), non-esterified fatty acid (NEFA), and glucose were measured in six male and six female mithuns, every 4 h for 24-h period. These three metabolites exhibited remarkable and surprising dynamics, which would not have been detected without measurements covering the entire diurnal cycle. However, Cosinor analysis did not statistically validate any sinusoidal rhythm for either of the metabolites.Holm-Sidak multiple comparisons revealed statistically significant (P ˂ 0.05) differences in glucose concentration across all the selected circadian-time points and in NEFA content at only 03:00 and 15:00 h between the two sexes. Pearson correlation revealed that plasma glucose concentration significantly correlated (r = 0.85, P ˂ 0.0001) with AAN content but not with NEFA.