Genetics And Production Performance Of Comb Types In Qingyuan Partridge Chickens And Guangxi Partridge Chickens

The comb,as an important organ for heat dissipation and an indicator of precocious maturity shows rich phenotypic variation.Besides,the comb,also as an important and natural packaging trait,plays an essential role when chicken meat gets into the fresh meat market.Trigeminal comb is a special comb,but still few reports are known despite of as a natural anti-counterfeiting mark of carcass,especially for its classification,nomenclature,genetic law and impact on production performance.In this study,we investigated the variation types and distribution ratios of single and trigemina comb in Qingyuan partridge chicken and Guangxi partridge chicken.In term of the hybridization experiments of 8 different mating types,the genetic law of trigeminal comb traits was named and studied.Meantime,This experiment studied the differences of productivity among different comb teeth in Qingyuan partridge chickens having single combs.The differences of both the trigeminal and single comb groups in different stages were compared.This study is to provide a theoretical basis for the further study of the molecular mechanism of the variation and inheritance of the trigeminal comb of Qingyuan partridge chickens and Guangxi partridge chickens,as well as the acceleration of the establishment of new trigeminal comb strains of Qingyuan partridge chickens.Results are of great significance to the heritage improvement and brand building of Qingyuan partridge chickens.The results are as follows:The results showed that the total proportion of single comb and side sprigs comb in Qingyuan partridge chickens were 94%and 6%,respectively.Of the side sprigs combs,there were3.7%trigeminal comb,1.4%left sprigs comb,and 0.9%right sprigs comb.In the protected breed population,the proportion of single comb and side sprigs comb were 96.6%and 3.4%(trigeminal comb 2.5%,left sprigs comb0.7%,right sprigs comb 0.2%),respectively.While,that in the early feathering line was 94.5%and 5.5%(trigeminal comb 3.6%,left sprigs comb 1.1%,and right sprigs comb 0.8%),respectively.In addition,that in the late feathering line was 92.4%and7.6%,respectively.Of the side sprigs combs,there were 4.4%trigeminal comb,2.1%left sprigs comb,and 1.1%right sprigs comb.In relation to Guangxi partridge chickens,the proportion of single comb and side sprigs comb were 94.2%and 5.8%(trigeminal comb 2.7%,left sprigs comb 1.9%,and right sprigs comb 1.2%),respectively.The proportion of trigeminal comb I(48%)and trigeminal comb II(52%)in the population with standard trigeminal crows was close to 1:1.In general,the genetic diversity of chicken comb was well preserved in the development of specialized strains.Thus,the auto-sexing composed lines of trigeminal comb of Qingyuan partridge chickens could be established by population expansion.According to the investigation on the diversity of single comb in different breeds,results showed that the number of large comb teeth of Qingyuan partridge chickens and Guangxi partridge chickens was mainly 5,and the total number of comb teeth was mainly 5,6 and 7.The production performance were not significantly different(P>0.05)among the growth indexes of male chickens with different large comb teeth.The production of female chickens with large comb teeth≥6 were better.When the total of comb teeth was divided into groups,the production performance of hens having the total 7 comb teeth is better.The number of large comb teeth of hen was significantly positively correlated with itsbody weight at the 42 age old(P<0.01),and the correlation coefficient was 0.161.Accordingly,results showed that the non trigeminal comb genotypes were Ss S~1S~1,SSS~1S~1,SSS~1s~1and Ss S~1s~1,and the trigeminal comb genotypes were Sss~1s~1,SSs~1s~1,ss S~1S~1,ss S~1s~1and sss~1s~1.These findings were consistent with the proportion distribution of phenotypic results in a large degree,but the hypothesis still failed to explain the genetic law of left sprigs comb and right sprigs comb.The genetic law of the trigeminal comb might be controlled by multi-genes,。The production performance of Qingyuan partridge chickens in different comb types was compared.Results found that the variation in different comb types are mainly concentrated on the indexes including comb height,comb length and wattle length during the early and middle stages of life.In general,the trigeminal comb had no significant effect on the performance of early maturity in Qingyuan partridge chickens,and the breeding of early maturity should be further strengthened.Then,the correlations of the body weight of different comb types with early maturity traits were analyzed.There was a positive correlation of comb height,comb length and wattle length of different comb types between 42 and 98 days,and the correlation coefficient was between 0.498 and 0.763.there was also a positive correlation of body weight,comb height,comb length and wattle length of different comb types of hens between42 and 98 days,respectively,with the correlation coefficient was between 0.330 and0.928.