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The present study evaluated the effects of cyclic heat stress (cHS) and diets supplemented with a combination of glycine and N-acetylcysteine (GlyNAC) on growth performance, serum antioxidant capacity and glutathione (GSH) content in serum, liver and pectoral muscles of Cyan-shank partridge chickens. Sixty-four male chickens (60 days old) were selected and randomly divided into four groups: CON + TN (basal diet; TN, thermoneutral condition with continuous 25 °C), GlyNAC + TN (basal diet + GlyNAC; TN), CON + cHS (basal diet; cHS, 32 °C for 4 h daily), and GlyNAC + cHS (basal diet + GlyNAC; cHS). The experimental period was 7 days. Results indicated that cHS significantly increased rectal temperature of chickens during heat treatment period (P < 0.05). Nevertheless, neither cHS nor GlyNAC supplementation affected growth performance or serum malondialdehyde levels. GlyNAC supplementation increased the GSH content in serum, liver and pectoral muscle (P < 0.05), but neither cHS nor GlyNAC altered jejunal GSH levels. The cHS decreased the ratio of villous height to crypt depth (V:C) and increased hepatic inflammatory infiltration score (IIS), while GlyNAC supplementation improved both the V:C ratio and hepatic IIS (P < 0.05). In liver, cHS downregulated the protein expression of caspase 3 and glutamate-cysteine ligase modifier subunit (GCLM), as well as the mRNA expression of GCLM gene. In contrast, GlyNAC supplementation upregulated hepatic caspase 3 protein expression and the mRNA expression of GCLM genes (P < 0.05). In conclusion, dietary GlyNAC supplementation maintained the elevated GSH content in both serum and liver, while alleviating cHS-induced impairment of jejunal integrity and hepatic inflammatory infiltration.
Wang et al. (Wed,) studied this question.