Study On Precocious Puberty Of Qingyuan Hemp Rooster

Sexual maturity of chickens marks the beginning of reproductive activities and is an important economic trait.It is therefore of significance to study and cultivate individuals with precocious puberty characteristics as a key selection for high-quality broiler.The precocious puberty of roosters is mainly judged by the cockscomb,which is an important second sexual trait.The development of the cockscomb is closely related to gonad development,to data there is still lack of study on the related traits on precocious puberty and its molecular mechanism.In this study,the body weight and cockscomb phenotype data of the Qingyuan hemp rooster population(high cockscomb group and dwarf cockscomb group)with extreme cockscomb height traits at 42 ～ 140 days of age were systematically collected.Rooster with high and dwarf cockscomb were slaughtered at 56,79,112,126 and140 days of age.The difference of carcass performances were compared and analyzed.The fitting analysis of body weight and cockscomb height among the two groups were carried out,and the principal component analysis was used to conduct carcass performances of 56 and 79day-old roosters.The cockscomb and testicular tissues of individuals with high and dwarf cockscomb at 79-day-old were collected.The tissue development of cockscomb and testis were studied by histological anatomy.RNA-seq technique was used to analyze the genomic expression differences of individuals with extreme cockscomb height traits at 56-day-old,to explore the mechanism of related candidate genes and regulatory factors in spatio-temporal expression,and to reveal the genetic regulation mechanism of precocious puberty in roosters.The results showed that:1.By fitting the characters of the two groups with the growth curves of Logistic,Gompertz and Bertalanffy,the crown growth and weight inflection points of the high crown group were earlier than those of the dwarf crown group,but the difference of the crown height of the inflection point was small.The inflection points of the body weight for both the two groups were clearly between the 56 to 63 days old,and those of the cockscomb height were between the 56 to 77 days old.The inflection point of the cockscomb was before than that of body weight in the high comb group,while after in dwarf comb group.2.There was a significant difference in developmental indicators of combs and testicles between the high and dwarf cockscomb groups at the age of 56,79,112,126 days(0.01﹤P<0.05).The cockscomb height significantly different(0.01﹤P<0.05),while the testicular index was not different(P>0.05)between the high and dwarf cockscomb groups at the age of140 day when rooster were fully sexually mature.At the ages of 56,79,112 and 126 days,the cockscomb height and testicular index were significantly correlated(0.01﹤P<0.05),but the correlation coefficient decreased with the increase of age,of which the correlation coefficient did not significant at the age of e 140 days(P>0.05).3.Through the principal component analysis at the ages of 56 and 79 days,crown index and testicular index,as the first principal components,could reflect the gonadal development of roosters and be used as an evaluation index for the breeding of neutral precocious puberty.4.Through the morphology and histoanatomyof 79 day old Qingyuan hemp rooster,the coclscomb development of high comb rooster was better than that of dwarf crown rooster,which is mainly reflected in the change of capillary number and fiber cell number.The testicular development of high comb rooster was better than that of dwarf comb rooster,which was mainly manifested in testicular mass,the size of testicular seminiferous tubules and the number of spermatogonia arranged.5.There were 258 and 2030 differently expressed genes between high and dwarf cockscomb groups in cockscomb and testicle at 56 days of age,respectively.In terms of the GO analyses,both the cockscomb and testicle were mainly involved in the functions of extracellular space,extracellular domain and extracellular at different stages.KEGG pathway analysis showed that a number of lipid metabolism pathways were involved in the development of chicken cockscomb and testis,including Apelin signaling pathway,retinol metabolism,ECM receptor interaction and PPAR signaling pathway and so on.Aldehyde dehydrogenase 1 family member A1(ALDH1A1)may be a key gene in the development of chicken crown and testis,which provides a molecular basis for further scientific explanation of the relationship and difference between the development of cockscomb and testis.