Nutrient Utilization in Pigs and Chicks Treated With Lipopolysaccharide: Lysine, Threonine, Arginine, Sulfur Amino Acids and Vitamin E

163 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1998.It is becoming commonly accepted that reductions in feed intake, lean muscle accretion, and growth in immunologically challenged animals result from increased cytokine activity, but this has not been directly tested. As a first step towards addressing this issue, crossbred barrows and gilts (11.6 kg BW) were injected with either saline or Escherichia coli lipopolysaccharide (LPS) following 12 h of feed deprivation. Immunological stress was induced by LPS as indicated by increased plasma levels of the cytokines tumor necrosis factor-$\alpha$ (TNF-$\alpha$ and interleukin-6 (IL-6), and the catabolic hormone cortisol. The increased secretion of cortisol in pigs injected with LPS was followed by an increase in protein degradation, as evidenced by plasma urea nitrogen values that were increased two- and three-fold at 8 and 12 h after LPS injection. It is apparent that nutrient deficiencies or excesses can affect the immune response of LPS-challenged animals. Severe dietary deficiencies of lysine, threonine or arginine ameliorated the negative effects of LPS in chicks. In addition, pigs receiving high levels of D-$\alpha$-tocopherol (600 mg i.m. per day for 3 days) had lower peak levels of IL-6 and cortisol following LPS administration than pigs not receiving supplementary $\alpha$-tocopherol. Several chick assays were conducted to evaluate the effects of repeated LPS injections on the requirements for and the utilization of lysine, threonine and arginine. In general, these studies demonstrated that stimulation of the immune system by multiple injections of LPS reduces performance and decreases the absolute quantity of amino acids required for maximal protein accretion. The decreased need for amino acids is apparently due to a reduction in the chick's capacity to accrete protein, because LPS-injected chicks accreted less protein than saline-injected chicks. However, the concentration of dietary amino acids required to maximize performance was generally unaffected by immunological stress, as the reductions in feed and amino acid intake associated with LPS administration were proportional to the decreased need for amino acids in these chicks. The efficiency with which lysine, threonine and arginine were utilized for whole-body protein accretion was not altered by LPS administration.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD