Effects And Mechanism Of Supplemental Zince On Carcass Traits And Meat Quality Of Broilers

This study was conducted to investigate the effects of supplemental zinc (Zn) source and level on growth performance, carcass traits, meat quality, tissue Zn content and correlated enzyme activities in broilers. Furthermore, the molecular regulation mechanism of Zn on meat quality was studied.468 one day old Arbor Acres (AA) male broilers were divided into 13 groups to study the effects of supplemental Zn source and level on growth performance, carcass traits and serum biochemical indicators. Dietary treatments included the corn-soybean meal based diet (control) and the basal diet supplemented with 60,120 or 180 mg Zn/kg as ZnSO4.7H2O (22.66%Zn), Zn-AAC (slight complexation,11.93%Zn, Qf=6.5), Zn-Pro B (medium complexation,13.27%Zn, Qf=30.7), or Zn-Pro A (strong complexation,18.61%, Qf= 944.0). The experiment period was 42 days. The results showed that:1) Dietary supplemental Zn source and source x level interaction had no effect on growth and carcass traits in broilers; 2) Compared with the control, Zn supplement increased average daily feed intake (ADFI), average daily gain (ADG), percentage of eviscerated yield (P<0.1) and serum alkaline phosphatase (AKP) activity (P<0.1), but no significant difference was observed among supplemental Zn levels.2. Analysis of meat quality and tissue Zn content showed that:1) Dietary supplemental Zn source and source x level interaction had no influence on meat quality and tissue Zn concentration. Zn supplement improved b* value in breast muscle, pH at 24h and shear force in thigh muscle, drip loss and malondialdehyde (MDA) in breast and thigh muscle (P<0.1) and improved a* value in breast muscle (P=0.1159) compared with the control; 2) Compared with the control, dietary supplemental Zn significantly increased intramuscular fat (IMF) at the basis of fresh sample or dry matter (P<0.1) and Zn concentration in beast muslce, thigh muscle and liver (P<0.1).3. The results of fat metabolism and antioxydation showed that:1) The expression and activities of FAS, MDH, LPL in liver or abdominal fat were not influenced by dietary supplemental Zn source and the interaction Zn source and level. Compared with the control, supplemental Zn significantly increased activities of FAS, LPL in liver and MDH, LPL in abdominal fat. Besides, dietary Zn supplement increased the expression of MDH, FAS, LPL in liver and MDH, LPL in abdominal fat.2) Dietary Zn source, level and source x level interaction had no influence on MT, CuZn-SOD expression in liver, breast and thigh muscle, CuZn-SOD activity, concentration of MDA and MT in liver. Supplemental Zn increased MT concentration (P< 0.1) in liver and CuZn-SOD (P< 0.1) activity in liver, breast and thigh muscle, and decrease MDA concentration in liver. Besides, the results were supported by the gene expression of CuZn-SOD and MT in liver, breast and thigh muscle.4.3 breast muscle samples of the control and 120 mg/kg ZnSO4.7H2O group were chosen randomly and detected with three chicken 4×44 K gene chips. The results showed that, compared with the control, the expression of 415 genes significant changed (P< 0.01),230 genes were up-regulated and 185 genes were down-regulated (P< 0.01). Data of microarray provided more candidate genes involved in Zn modulating on meat quality in broilers.Based on this study, it was concluded that supplemental Zn can improve growth performance, carcass traits and meat quality. However dietary Zn source and interaction of Zn source and level had no influence on these characters. Dietary supplemental 60 mg/kg Zn (about 90 mg/kg Zn in diet) is benefit to meat quality and no further improvement for higher level of supplemental Zn.