Influences of dietary methionine and cysteine on metabolic responses to immunological stress by Escherichia coli lipopolysaccharide injection, and mitogenic response in broiler chickens
1997
Takahashi, K. | Ohta, N. | Akiba, A.Y.
The present experiments were conducted to investigate influences of dietary methionine and cysteine on metabolic responses to immunological stress induced by Escherichia coli lipopolysaccharide (LPS) injection, and concanavalin A (Con A)-induced mononuclear cell (MNC) proliferation in male broiler chickens. In Expt 1, chicks (12 d of age) were fed on a S amino acid (SAA)-deficient diet (5.6 g SAA/kg diet) or on three kinds of SAA-sufficient diet (9.3 g SAA/kg diet; low-, medium- and high-cysteine diets) which contained 2.8, 4.65 and 6.5 g cysteine/kg diet, respectively. Plasma alpha-1 acid glycoprotein (AGP) concentration and interleukin (IL)-1-like activity in chicks fed on the SAA-deficient diet were lower following a single injection of LPS than those in chicks fed on the SAA-sufficient diets. At 16 h after LPS injection, plasma Fe and Zn concentrations and body weight were reduced, but AGP concentration and IL-1-like activity in plasma were significantly increased. These changes in body weight, plasma Zn and Fe concentrations following injection of LPS were not affected by dietary methionine:cysteine ratios. Plasma AGP concentration and IL-1-like activity in chicks fed on the high-cysteine diet were, however, greater than those in chicks fed on the other diets following a single injection of LPS. In Expt 2, chicks (7 d of age) were fed on the SAA-sufficient diets as in Expt 1 for 10 d. MNC proliferation in spleen induced by Con A in chicks fed on the high-cysteine diet was greater than that in chicks fed on the low- or medium-cysteine diet. The results suggest that dietary cysteine has an impact on the immune and inflammatory responses.
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