| Fasting-induced moulting is an effective way to prolong the raising of laying hens,and it is one of the effective ways to save cost and increase efficiency in our country’s laying hen industry.Fasting-induced moulting technology is very mature,but its mechanism of remodeling of ovarian function is still unclear.In order to explore the mechanism of ovarian function remodeling during the fasting-induced moulting process in laying hens.In this study,162 Guifei chickens(529-day-old)of uniform body weight with an egg production rate of 60% were selected,and randomly divided them into the FM group(fasting).treatment)and NC groups(normally fed),9 replicates per group,9 birds per replicate,were subjected to fasting-induced moulting.Changes in the weight loss rate and egg production rate of the flock during the moulting process were counted,in the day before fasting(F0),3 days of fasting and water deprivation(F3),16 days of fasting(F16),and 6 days of resumption of feeding(R6),15 days of resumption of feeding(R15),and 32 days of resumption of feeding(R32),the number of follicles,the changes of KIT-PI3K-PTEN-AKT signaling pathway,and the expression of GDF-9 at different developmental stages in the ovary,serum reproductive hormone levels and ovarian antioxidant levels were studied,the results are as follows:The body weight of the test flocks decreased the fastest in the first 3 days of the fasting period,and recovered the fastest in the first week after resumption of feeding;The chickens stopped production after 7 days of fasting,and resumed production when the body weight returned to about 94% of the pre-fasting level,and the egg production rate rose rapidly after the body weight stabilized,and returned to the pre-fasting level(62.5%)at R32.At F16 and R6,the number of mature follicles decreased significantly,the contents of FSH,LH,E2 and P4 in serum decreased,the number of primary follicles and secondary follicles increased significantly,and the relative expression levels of KIT,PI3 K,AKT,and GDF-9 increased significantly,PTEN decreased significantly;at R15 and R32,the number of mature follicles gradually increased,at R32,the number of large white follicles was significantly more than that of NC group,and there was no significant difference between small yellow follicles and grade follicles,and serum FSH,LH,E2 and P4 The content of PI3 K and AKT decreased significantly in R15,while the number of primary follicles and secondary follicles decreased.The relative expression of PTEN increased significantly at R15,and the relative expression of PI3 K and AKT decreased significantly at R32,GDF-9 continued to maintain a high expression state;At R32,the enzymatic activities of T-AOC,SOD and GSH-Px in the ovary were not significantly different from those in the NC group.In summary,the mechanism of action of fasting-induced moulting in Guifei chickens may be that during the fasting period,fasting prevents lipid synthesis and transport in the liver and down-regulates the release of pituitary gonadotropins,which hinders the development of mature follicles,causes a large number of the mature follicles atresia is blocked and reabsorbed by the body,thereby activating the KITPI3K-PTEN-AKT signaling pathway to promote the activation of primordial follicles in the fasting period and the initial stage of recovery,and by increasing the expression level of GDF-9,it promotes the activated follicles to develop into primary follicles and Secondary follicle stage;after resumption of feeding,with the recovery of body weight,lipid synthesis and transport in the liver tend to be normal,and the secretion of gonadotropins gradually increases,which promotes the rapid development of primary follicles and secondary follicles to the mature follicle stage and ovulation,and realizes the follicles in the growing follicle pool is renewal,which may increase the number of follicles in the growing follicle pool and reduce the atresia rate of follicles,so that the flock can smoothly enter the next egg laying cycle and can reach the peak of egg production again. |
