| This experiment was conducted to evaluate the effects of dietary supplementation of MHA-Zn on laying performance,antioxidant capacity and reproductive performance of breeders during later laying period.Focusing on the problems of reduced laying rate,poor egg quality,reduced reproductive performance,shortened breeding life,and environmental pollution caused by the use of inorganic zinc in the production of broiler breeders during the late laying period.Explore the technology of reducing MHA-Zn to replace ZnSO4 in the diets of broiler breeder.It is expected to provide a theoretical basis for its application in the actual production of breeders.A total of 600 Hubbard(56-week-old)broiler breeders were randomly assigned into 5 treatment groups with 6 replicates for each treatment and 20 birds per replicate.Broiler breeders in the control group were fed the basal diet(zinc content was 27.81 mg/kg)supplemented with 100 mg/kg ZnSO4(as zinc),and broiler breeders in the experimental groups were fed the basal diet supplemented with 25,50,75 and 100 mg/kg MHA-Zn(as zinc).The broiler breeders were fed on the treatment diets for 10 weeks after a 2-weeks adaptation period(no additional zinc).The results showed as follows:1)Compared with ZnSO4 group,dietary supplementation with 75 and 100 mg/kg MHA-Zn significantly increased the laying rate of broiler breeders during the late laying period(P<0.05);Dietary supplementation with 50,75 and 100 mg/kg MHA-Zn significantly increased egg weight(P<0.05),and decreased feed/egg(P<0.05);Dietary supplementation of MHA-Zn instead of ZnSO4 had a decreasing tendency in broken egg rate(P<0.10);2)Dietary supplementation of 100 mg/kg MHA-Zn instead of ZnSO4 can significantly increase the eggshell strength of broiler breeders during later laying period(P<0.05);Compared with ZnSO4 group,dietary supplementation of MHA-Zn had a decreasing tendency in eggshell thickness(P<0.10);Compared with ZnSO4 group,the protein height and HU of the 50,75 and 100 mg/kg MHA-Zn groups were significantly increased(P<0.05);3)Dietary supplementation of MHA-Zn can significantly reduce the zinc content in the excrement of broiler breeders during the late laying period(P<0.05),while increase the utilization of calcium to varying degrees.Compared with ZnSO4 group,dietary supplementation with 100 mg/kg MHA-Zn increased the utilization rate of calcium(P<0.05);Dietary supplementation of MHA-Zn had a increasing tendency in the utilization rate and serum content of zinc(P<0.10).With the increase of MHA-Zn addition,the zinc content of egg yolk increases linearly(P<0.05);4)Compared with ZnSO4 group,dietary supplementation with 50,75 and 100 mg/kg MHA-Zn significantly decreased the content of MDA in the serum of broiler breeders during the late laying period(P<0.05);Dietary supplementation with 75 and 100 mg/kg MHA-Zn increased the activity of SOD and T-AOC in the liver of broiler breeders during the late laying period(P<0.05);5)Compared with the ZnSO4 group,dietary supplementation with 75 mg/kg MHA-Zn significantly increased the fertilization rate of broiler breeders during the late laying period(P<0.05);Compared with the ZnSO4 group,the offspring of the 50,75 and 100 mg/kg MHA-Zn group the birth weight of chicks was significantly increased(P<0.05);6)The addition of different levels of MHA-Zn in the diet instead of ZnSO4 has a significant effect on the serum FSH、LH、PRL、E2、P4、T3 and T4 levels of broiler breeders in the late laying period(P<0.05),and it increases linearly with the increase of MHA-Zn addition(P<0.05);7)With the increase in the amount of MHA-Zn added,the number of SYFs increased linearly(P<0.05),and with the increase of MHA-Zn addition,the ovarian weight and the number of LWFs showed a linear increase trend(P<0.10);8)Compared with the ZnSO4 group,dietary supplementation with 75 mg/kg of MHA-Zn can significantly increased the enrichment of FSHR mRNA in the granular layer of F2 follicles and the enrichment of LHR mRNA in the granular layer of F1 follicles of broiler breeders during the late laying period(P<0.05);9)Compared with ZnSO4 group,dietary supplementation of 75 mg/kg MHA-Zn had the best economic benefit of broiler breeders during the late laying period.Conclusions:It is concluded that the use of MHA-Zn in the diet instead of ZnSO4 can improve the laying performance,antioxidant performance and reproductive performance of breeders during later laying period.Under this experimental conditions,the optimal dosage of supplemental MHA-Zn was 75 mg/kg. |
