Mechanism Of GnIH In The Effects Of Antibiotics On Laying Performance Of Ducks

In this paper,effects of three antibiotics including amoxicillin,florfenicol and rifampicin on laying performance,egg production,egg quality,gene expression,antioxidant index and immune index of laying duck,as well as effect of cultured cellular level in vitro on cell growth and secretion were with laying duck as model so as to reveal influential mechanism of antibiotics in process of laying eggs and action mechanism of GnIH,providing production guidance and scientific basis for production of laying duck.Experiment 1:Effects of three antibiotics including amoxicillin,florfenicol and rifampicin on laying performance,egg quality,related reproductive hormones,antioxidant levels and expression levels of genes related to reproduction in hypothalamic pituitary were studied.Results showed that SYF numbers treated by three antibiotics were less than that of starch group,among which,numbers of SYF and LWF in amoxicillin group were significantly lower than that of starch group;based on related hormone,compared with that of starch group,FSH,LH,E₂ and P₄ level in blood of three antibiotics groups decreased;in terms of gene expression,application of three antibiotics not only improved expression level of GnIH,Gn IH-R,GnRH and VIP in hypothalamus,but also increased expression level of Gn IH,GnIH-R,GnRH and PRL in pituitary;in terms of egg quality,amoxicillin,florfenicol made thickness of eggshell decreased,florfenicol made malformation increased.In terms of blood biochemical parameters,compared with that of starch group,three antibiotics made level of AKP,ALT,AST,TC and TG increased,while LDH level decreased.As for immune indices of body fluids,three antibiotics also had an effect on level of TP and ALB in blood,among which amoxicillin made TP increased,ALB decreased,while florfenicol and rifampin were opposite.In terms of antioxidant level,SOD level of three antibiotics decreased greatly.Results showed that three antibiotics had inhibitory action on follicle before grade development,florfenicol and rifampicin mainly inhibited generation of SYF,which had some certain effect on indexes of egg quality,as well as obvious effect on oxidation capacity,immunity and blood biochemical index.Experiment 2:Effects of of three antibiotics including amoxicillin,florfenicol and rifampicin on related reproductive hormones and gene expression levels of ovarian granulosa cells within 48h were studied.Results showed that effect of florfenicol on cell growth was the most,followed by rifampicin,while,amoxicillin had no obvious effect on cell growth.Effect of florfenicol on E₂ secretion was the most,florfenicol and rifampicin for ACT.Results showed that three antibiotics could have an obvious effect on granulosa cell growth,hormone secretion and gene expression,with effects of florfenicol and rifampicin as the most significant,among which level of E₂,P₄ and ACT increased and INH decreased.Experiment 3:Effects of exogenous Gn IH on laying performance,egg quality and related reproductive hormones of laying ducks as well as expression level of related reproductive genes in hypothalamic pituitary.Results showed that during experiment d9^d17,egg quality of treatment group was lower than that of control group,autopsy found that SYF and LWF were lower than that of control group,and blood level of FSH,LH and P₄ in treatment group was lower than that of control group in d5^d17.Results showed that exogenous Gn IH could inhibit follicular development and laying performance mainly follicle development before grading follicles by having an effect on expression and secretion of related reproductive hormones.