Effects of chlorogenic acids-enriched extract from Eucommia ulmoides leaves on growth performance, stress response, antioxidant status and meat quality of lambs subjected or not to transport stress

This study was conducted to evaluate the effects of chlorogenic acids-enriched extract (CGAE) from Eucommia ulmoides leaves on growth performance, stress response, antioxidant status and meat quality of lambs subjected or not to transport stress. Forty eight weaned male Huzhou lambs (a local breed, average body weight 17.3 +/- 1.58 kg) were equally divided into three treatments for a 56 d feeding period and fed the basal diet supplemented with 0 (CGAEO), 1 (CGAE1) or 5 (CGAE5) g of CGAE/kg of the basal diet (dry matter basis). After the feeding trial, eight lambs per treatment were randomly selected, blood sampled and slaughtered without road transport. The remaining 24 lambs were transported for 8 h to simulate stress. After transport, all lambs were blood sampled and slaughtered. Dietary CGAE supplementation did not affect average daily gain, dry matter intake and feed efficiency of lambs. Significant interaction between road transport and dietary CGAE supplementation was found for the glucose concentration (P < 0.01) in blood and the pH(24) value (P < 0.05) and malondialdehyde (MDA, P < 0.01) content in meat. Lambs fed the CGAE1 and CGAE5 diets had lower (P < 0.01) glucose and triiodothyronine (T-3) concentrations, creatine kinase (CK) activity, white blood cell (WBC) count and neutrophil (NEU): lymphocyte (LYM) ratio and higher (P < 0.01) LYM count than lambs fed the CGAEO diet. Lambs fed the CGAE5 diet had higher superoxide dismutase (SOD, P < 0.01) activity and total antioxidant capacity (T-AOC, P < 0.01) of serum and T-AOC (P < 0.05) of liver and lower serum cortisol concentration (P < 0.01) and MDA (P < 0.05) contents in serum and liver compared with lambs fed the CGAEO diet. Road transport increased (P < 0.01) cortisol, glucose, T-3 and thyroxine (T-4) concentrations, CK activity and WBC count in blood and MDA contents in serum and liver and decreased (P < 0.05) SOD activity and T-AOC of serum. Dietary CGAE supplementation decreased pH(24) value (P < 0.05) and MDA content (P < 0.01), but increased (P < 0.05) cooking loss of meat. In contrast, the opposite was true for the effects of road transport on pH(24) value (P < 0.05), MDA content (P < 0.01) and cooking loss (P < 0.01) of meat. In conclusion, dietary CGAE supplementation did not affect the growth performance and improved certain stress indicators, meat quality and antioxidant status of lambs, especially for transport-stressed lambs.