Effects of protein and/or energy restriction for six weeks on antioxidation capacity of plasma and gastrointestinal epithelial tissues of weaned kids

Sixty weaned kids were allocated to four groups to investigate effects of protein and/or energy restrictions on antioxidation capacity of the plasma, rumen epithelium and jejunum mucosa. The four treatments were control, either energy restriction (ER) or protein restriction (PR), and combined energy and protein restriction (EPR). The experimental period consisted of 6 weeks nutrient restriction followed with 9 weeks nutrient recovery. Compared with antioxidation capacity of the plasma in control group, energy restriction decreased (P<0.05) the activities of catalase (CAT) on day 21 and glutathione reductase (GR) on day 41, and increased malondialdehyde (MDA) content (P<0.05) on days 21 and 41; protein restriction decreased (P<0.05) the GR activity on day 41, and increased (P<0.05) MDA content on day 21; combined energy and protein restriction decreased (P<0.05) the activities of CAT, superoxide dismutase (SOD) and GR on days 21 and 41, and increased (P<0.05) MDA content on days 21 and 41. Meanwhile, energy restriction decreased (P<0.05) the CAT activity of the rumen epithelium, GSH-Px activity of the jejunum mucosa, and GSH content of the rumen epithelium and jejunum mucosa; protein restriction decreased (P<0.05) the CAT activity of the rumen epithelium and GR activity of the jejunum mucosa, and GSH content of the rumen epithelium and jejunum mucosa; combined energy and protein restriction decreased (P<0.05) the CAT activities of the rumen epithelium and jejunum mucosa, SOD, GSH-Px and GR activities of the jejunum mucosa, GSH content of the rumen epithelium and jejunum mucosa. After 9 weeks nutrient recovery, there were no differences (P>0.05) in plasma antioxidation capacity among four groups; however, the SOD activities of the jejunum mucosa in ER, PR and EPR, GR activities of jejunum mucosa in PR and EPR, and the SOD mRNA level of the jejunum mucosa in ER, PR and EPR still remained lower (P<0.05) than those in control. The results indicate that antioxidation capacity of the plasma, rumen epithelium and jejunum mucosa can be reduced by energy and/or protein restrictions in weaned kids; the reduced antioxidation capacity of the rumen epithelium and jejunum mucosa by 6 weeks nutrient restriction can not fully be retrieved after 9 weeks nutrient recovery.