Effect of Dietary Methionine to Cysteine Ratio on Inflammatory Responses in Chicks with Multiple Injections of Escherichia coli Lipopolysaccharide

摘要

Effects of dietary methionine (Met) and cysteine (Cys) on plasma interleukin-1 (IL-1) like activity and alpha 1-acid glycoprotein (AGP) concentration were studied in chicks injected repeatedly with Escherichia coli lipopolysaccharide (LPS). Male broiler chicks fed a Met (0.62%)- or Cys (0.62%)-rich diet (0.94% of sulphur amino acid content in diets) were daily injected intraperitoneally with LPS at levels of 0.25 or 1 mg per kg body weight over 13 days. The highest AGP concentration in plasma was found on day 1 or 2 of LPS injections, and thereafter the concentration decreased by day 4. On days 1 and 2, plasma AGP concentration in chicks received 1 mg of LPS was higher than that in chicks injected with 0.25 mg of LPS in both dietary groups. Plasma AGP concentration in the Met rich diet fed chicks was higher than that in the Cys-rich diet fed group on days 6 and 14 in the 0.25 mg LPS injected group. The Cys-rich diet fed chicks had greater plasma AGP concentration than the Met-rich diet fed group onday 1 in the Img LPS injected group. The highest IL-1 like activity in plasma was found on day 2 and thereafter the activity decreased by day 4 in all groups. The IL-1 like activity in chicks fed the Cys-rich diet was greater than that in chicks fed theMet-rich diet on day 1 in the 0.25 mg LPS injected group and on day 2 in 1 mg LPS injected group. On days 4, 10 and 14, chicks fed the Met-rich diet had higher IL-1 like activity than chicks fed the Cys-rich diet in the Img LPS injected group. The results confirmed that ratio of Met to Cys in diet is a modulator of inflammtory response to LPS in chicks. The results also suggested that the higher inflammtory responses of chicks fed the Cys-rich diet to the higher dose of LPS is temporary, and chicks fedthe Met-rich diet have almost similar or higher sensitivity to repeated injection of LPS compared with chicks fed the Cys-rich diet.