Effects of continuous long-term intravenous infusion of long-chain fatty acids on feeding behaviour and blood components of adult sheep.

Albumin complexes of palmitic, stearic and oleic acids were continuously infused intravenously into adult sheep to investigate their effects on feeding behaviour and blood components. They were compared with saline infusions as during a preliminary test albumin alone showed no influence on voluntary food intake. Oleic and palmitic acid infusions induced a significant decrease of the voluntary food intake, relative to saline infusion. Food intake also decreased in experimental sheep when stearic acid was used, though not significantly. For all the tested fatty acids, blood beta-hydroxybutyrate and acetoacetate concentrations, plasma lipid content and the distribution of fatty acids in triacylglycerol remained unchanged. Oleic acid infusion induced the following significant changes of blood composition between control and experimental sheep: increased free fatty acid (FFA) concentration, increased oleic acid and decreased palmitic acid proportions in FFA and an increased amount of oleic acid balanced by a decreased linoleic acid content in phospholipids and cholesteryl esters. The only significant changes observed with the palmitic acid infusion were: decreased linoleic acid content in phospholipids and cholesteryl esters and increased oleic acid content in cholesteryl esters. The stearic acid infusion induced a decrease of stearic acid quantity in phospholipids and a corresponding increase in oleic acid in phospholipids and cholesteryl ester. It is suggested that these long-chain fatty acids might affect the long-term control of voluntary food intake in ruminants.