Fig. 4

Antioxidant status and immunity of laying hens. a Gene expression levels of thioredoxin (TXN), thioredoxin reductase (TXNR), and cytochrome b5 reductase (CYB5R) and b GSH/GSSG contents in the liver of the old and young hens in Exp. 1. *means P < 0.05; **means P < 0.01. c Effects of dietary supplementation of AA on T-AOC and malonaldehyde (MDA) level and d Total GSH, GSSG, and GSH concentrations in the liver of old laying hens in Exp. 2. Within each panel, means without a common letter differ at P < 0.05