A simple method for measuring albumin-bound non-esterified fatty acid concentration in laying-hen plasma.

Selective precipitation of triglyceride-rich (TGR) lipoproteins with dextran sulphate and magnesium chloride provides a simple and effective means of determining albumin-bound non-esterified fatty acids, (NEFA) in laying-hen plasma. Albumin-bound NEFA concentrations in the plasma of laying hens fed ad libitum are very low. Most of the NEFA are associated with TGR-lipoproteins, and their concentration is directly proportional (r = 0.82) to TGR-lipoprotein concentration. Subcutaneous injection of glucagon into laying hens produces an approximately 50% increase in total plasma NEFA concentration that persists for at least 2 hr. Most of this increase occurs in the TGR-lipoproteins, but albumin-bound NEFA concentrations increase at least 5-fold before rapidly returning to near control values. These results demonstrate the importance of measuring both albumin- and TGR-lipoprotein-bound NEFA in studies of plasma fatty acid metabolism in the laying hen.