Effect Of Zinc-Bearing Zeolite-Clinoptilolite On Performance, Immunity And Antioxidant Function Of Laying Hens

The aim of this study was to evaluate the effect of zinc-bearing zeolite-clinoptilolite (ZnCP) on performance, serum hormones, serum parameters, enterobacteria, antioxidant and immunity function, and MT, Nrf2, CuZn-SOD, GSH-Px gene expression of hens during fastigium laying period. The study was divided into three trials and the results are as follows:The first trial was conducted to study the effects of ZnCP on performance, level of hormones serum parametersand enterobacteria of laying hens. A total of 648 30-week-old Hy-Line Brown laying hens were randomly allocated to six groups with six replicates of 18 birds. The dietary treatments were as follows:(1) basal diet supplemented with Zn-sulfate (80 mg/kg from ZnSO4); (2) the control diet supplemented with antibiotics (40 mg/kg of bacitracin zinc); (3) a ZnSO4-deficient diet supplemented with ZnCP at level of 0.11%, 0.23%,0.34% and 0.46%(supplying 20,40,60,80 mg/kg of Zn), respectively. The results indicated that all ZnCP groups had no significant effect on laying rate, average egg weight, feed intake and feed:egg ratio.0.23%,0.34% and 0.46% ZnCP decreased broken eggshell rate compared with the control group (P<0.05). All ZnCP groups increased serum FSH level compared with the control group at 4 wk (P<0.05). The level of E2 in serum were significantly increased by 0.46% ZnCP at 8 wk (P<0.05).0.46% ZnCP increased serum GLU content significantly at 4 wk (P<0.05).0.23%,0.34% and 0.46% ZnCP decreased serum TC and TG content compared with the control group at 4 wk (P<0.05). Supplementation of 0.34%,0.46% ZnCP increased BUN content in serum while serum TG level was decreased by 0.11%,0.46% ZnCP at 8 wk (P<0.05). Adding 0.46% ZnCP had higher E2 and LH level at 8 wk in serum than the antibiotic group (P<0.05). The level of BUN in serum was significantly decreased by 0.34%,0.46% ZnCP groups (P<0.05). Enterobacteria were not affected by all ZnCP (P>0.05).The second study was conducted to investigate the influence of ZnCP on the serum, tissues antioxidant and immunity function of laying hens. The materials and methods were the same as that in trial 1. The results showed that liver T-SOD and CuZn-SOD activity was increased by 0.46% ZnCP (P<0.05).0.23%,0.34% and 0.46% ZnCP increased CAT and GSH-Px activity in liver compared with the control group (P<0.05). Serum T-SOD activity was increased by 0.34% ZnCP at 4 and 8 wk (P<0.05). Supplementation of 0.34% and 0.46% ZnCP decreased serum MDA content at 8 wk (P<0.05). The yolk MDA content was significantly lower than the control and antibiotic groups at 4 wk by all ZnCP groups, and so the yolk T-AOC was significantly higher than the control and antibiotic groups (P<0.05). 0.34%,0.46% ZnCP increased yolk T-SOD activity at 8 wk. Yolk CuZn-SOD activity was increased by 0.46% ZnCP (P<0.05). Supplementation of 0.23% ZnCP decreased yolk MDA content significantly (P<0.05). Supplementation of 0.23% ZnCP increased CAT and GSH-Px activity in liver significantly compared with the antibiotic group (P<0.05). All ZnCP groups increased GSH-Px activity and GSH content in serum significantly compared with the antibiotic group at 4 wk (P<0.05).0.34%,0.46% ZnCP increased yolk T-SOD activity significantly at 8 wk (P<0.05).0.34% ZnCP increased the level of ileal mucosa, serum IgG significantly compared with the antibiotic group at 8 wk (.P<0.05).The third study was conducted to study the effects of ZnCP on the MT, antioxidant function genes expression. The materials and methods of control and antibiotic groups were the same as that trial 1. A ZnSO4-deficient diet supplemented with ZnCP at level of 0.23%, 0.34% and 0.46% (supplying 40,60,80 mg/kg of Zn). The results showed that all ZnCP groups can significantly increased the expression of MT4, Nrf2 mRNA in jejunal mucosa compared with the two control groups (P<0.05).0.23%,0.46% ZnCP significantly increased the expression of Nrf2 mRNA in liver compared with the antibiotic group (P<0.05).The results showd that ZnCP can improve the performance, immunity and antioxidant function of laying hens in some degree.