| The production performance and spermatogenesis of boars affect the gene flow of the entire pig breeding system.In all breeding programs,the selection of boars is highly intensive.The selection of replacement boars should not only pay attention to the characteristics of breed type,growth and development,body appearance and health status,but also pay attention to the symmetry and testicular size of their testicles.Thyroxine is a key regulating hormone for the differentiation and maturation of testicular Sertoli cells.In this experiment,hypothyroidism was induced after birth in boring boars,and the growth performance,sperm production ability and semen quality after sexual maturity were measured,and the effect of thyroxine on the proliferation and differentiation of pig testicular Sertoli cells was explored.Among the newborn boars,36 boars with similar genetic backgrounds and healthy body conditions were selected and set into 6 groups,each with 6 pigs,one control group and five experimental groups.Five experimental groups were added PTU(propylthiouracil)at different time periods to induce hypothyroidism.Experimental group 1(15-30 days old),experimental group 2(15-60 days old),and experimental group 3(15-30 days old).90 days old),experimental group 4(60-90 days old),experimental group 5(60-120 days old).The control group was fed basal diet without treatment.During the experiment,each boar’s weight,feed intake,back fat thickness(110kg),eye muscle area(110kg),lean meat ratio,feed to meat ratio,testicular coefficient(total weight of double testicles/carcass weight)were recorded.After boars are sexually mature,at least 3 boars in each group are selected for artificial semen collection to test their semen quality.Culture porcine Sertoli cells in vitro to detect the effect of thyroxine(T3)on the proliferation,maturation and differentiation of Sertoli cells.High-throughput transcriptome sequencing was used to analyze the differentially expressed genes of mature Sertoli cells and immature Sertoli cells induced by T3.Part of the signal pathway predicted by RNA-seq was verified by q RT-PCR and Western Blot.The results of the study are as follows:1.Growth performance: The 180-day-old sexual maturity weight of the control group is 128.0±3.000 kg,the daily gain is 0.8047±0.04358kg/day,the FCR is2.7007±0.0363,the backfat thickness is 19.25±2.87 mm,and the eye muscle area is50.50 ±1.73cm2,the lean meat rate is 60.80±2.37%.Compared with the control group,the sexual maturity weight,daily gain,FCR,eye muscle area of the experimental groups1 and 2 are not significantly different from those of the control group.The back fat thickness is significantly lower than that of the control group,and the lean meat rate is significantly higher than that of the control group.;The 180-day-old sexual maturity weight,daily gain,and FCR of the experimental groups 3,4,and 5 were significantly lower than those of the control group,and the back fat and lean rate were not significantly different from those of the control group;the experimental groups 3,5eyes The muscle area was significantly lower than that of the control group.There was no difference in the area of the 4 eye muscles of the experimental group and the control group.2.Spermogenic ability and semen quality: the ejaculate volume of the control group was 170.18±11.88 m L,the sperm density was 2.20±0.05 billion/m L,and the sperm motility was 92.03±0.64%.The ejaculate volume of experimental groups 1 and2 was 196.09±11.51 m L and 203.00±5.15 m L,respectively,which were significantly higher than those of the control group.The ejaculate volume of experimental group 3was 148.64±27.36 m L,which was significantly lower than the control group;the sperm density of experimental groups 1 and 2 The sperm density of 255±18 million/m L and258±22 million/m L were significantly higher than those of the control group.The sperm density of experimental group 3 was 0.88±62 million/m L,which was significantly lower than that of the control group.The sperm motility of experimental groups 1 and3 was significantly lower than that of the control group.There was no difference between the two groups.The sperm motility of the experimental group 2 was94.29±0.48%,which was significantly higher than that of the control group;the ejaculate volume,sperm density and sperm motility of the experimental groups 4 and 5were not significantly different compared with the control group.3.Sperm motility: Compared with the control group,the sperm motility ability of experimental group 1 and experimental group 2 was significantly improved.There was no significant change in the motility of sperm in experimental groups 3,4,and 5.4.Testicular development: The testis coefficient of the control group is6.78±0.39g/kg;The testis coefficient of the experimental group 1,2,and 5 was significantly higher than that of the control group;the experimental group 3 was significantly lower than that of the control group;the experimental group 4 had no significant difference compared with the control group.5.The effect of T3 on porcine testicular Sertoli cells: T3 can inhibit the proliferation of porcine testicular Sertoli cells and promote their maturation.It is found that T3 may regulate the proliferation and maturation of porcine Sertoli cells through the AKT/IKK/NFκB signaling pathway.Conclusion: 15-30 days and 15-60 days of age,induction of hypothyroidism in replacement boars has no significant effect on growth performance,but it can significantly increase the ejaculate volume,sperm density and sperm motility of boars,and promote testicular development.Thyroxine may be able to regulate the proliferation and maturation and differentiation of porcine Sertoli cells through the AKT/IKK/NFκB signaling pathway.It is recommended that 15-30 days of age induce hypothyroidism in boars to improve their spermatogenesis. |
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