Impact of CFA and dietary protein supply on acute phase responses and nitrogen retention in pigs

Abstract

During immune system activation, an increased competition occurs between amino acids (AA) for body protein deposition and for immune system functioning (Klasing and Johnstone, 1991; Sandberg et al., 2007). The production of acute phase proteins (APP) has been suggested to increase the demand for especially aromatic AA (Reeds et al., 1994). When muscle protein is mobilized to supply AA for APP production, this leads to an imbalance in AA available for body protein deposition, as the AA composition of APP differs largely from the composition of muscle protein (Reeds et al., 1994). As a consequence, increased AA oxidation and N loss via urine occur. It is hypothesized that the competition between AA increases when dietary protein supply is reduced. In addition, there is increasing evidence that the dietary protein or AA supply can modulate the inflammatory response during immune system activation (Grimble, 2001; Calder and Yaqoob, 2012). The aim of the present study was to quantify the interaction between acute phase protein (APP) responses, induced by immune system activation, and dietary protein supply on nitrogen (N) metabolism.