Study On Feather Development And Body Weight Performance Of Late Feathering Subtypes In Partridge Chickens

The early and late feathering are the traits that indicate the growth rate of newborn chick feathers,which are controlled by 4 alleles including K~n,K~s,K and k on the sex chromosome,and 3 alleles containing T,t~s,and t on the autosome,respectively,and affects the growth of primary feather,primary coverts,and tail feather.Due to the different roles of those alleles,the diversity of feather phenotypes of early and late feathering in chicks is formed.With in 24 h of being hatching,auto-sexing can be distinguished visually.According to the relative difference between primary feather and primary coverts,early-feathering are divided into 2 subtypes.One is R1 type,with the length of primary feathers is about 2 mm less than 5 mm longer than primary coverts.The other one is R2,and their primary feathers is 2 mm longer than primary coverts.Whiles the late-feathering are categorized into 6 subtypes including,primary feathers are longer than primary coverts up less than 2 mm longer named L1,primary coverts are longer than primary feathers are of equal length named L2,primary coverts are longer than primary feathers up less than 2 mm longer named L3,primary feathers of L4 are shorter than 2 mm primary-covert feathers,primary feathers do not extend out named L5 and primary feather and primary coverts do not extend out named L6.The trait of early and late feathering is a hereditary inheritance,which is widely used in the sex auto-identification by feather speed between male and female chicks.The homozygous(Ho)of late-feathering cock(Z~KZ~K)and the heterozygous(He)of late-feathering cock(Z~KZ~k)have different feather growth due to the different dose effects of the K gene.Therefore,to study the growth regulation of feather is of great significance on the further chick’s sex auto-identification and standardized management.This study,would primarily classify four subtypes of late-feathering.Furthermore,the primary feather,primary coverts,and tail feather.,primary feather maturity and body weight of late-feathering homozygote Qingyuan Partridge rooster chickens(M-line,QYM)and Tiannong commercial rooster(TNM)were investigated.The results are as follows:1.The growth of primary feather of QYM and TNM subtypes at the age of Day0 to 42 was determined.The results showed that the growth rate is highest in L1,followed by L2,L3,L4,L5,and L6.The growth peaks of the main wings of QYM and TNM subtypes were found at the age of 3 weeks old and 2-4 weeks old,respectively.The absolute growth curve of the primary feather is a bell-shaped symmetrical normal curve,while the relative growth curves are(inverse)parabolic are in line with the general growth laws.2.The growth of primary coverts in subtype QYM and TNM at the age of 0-42 days was measured.The results showed that the feather length of Ho L6 was the shortest during 1-2 weeks old,but turned out the longest subtype during 3-6 weeks old.Feather growth of subtypes grew rapidly during day 1 to 6,then declined rapidly after day 7,and showed to be stable after day 21.The peak of feather growth of L6was at the age of 2 weeks.The relative growth curves were all(inverse)parabolic,which was in line with the general growth law whereas the absolute growth curve was in the form of an exponential function.3.It is practical to distinguish the male and female of the third and fourth main wing feather from the overlying main wing feather.The identification of late-feathering subtype cocks is optimum within 24 hours after being hatching.Besides,the accurate identification for QYM and TNM of late-feathering type was from day 1 to 5 and day 1 to 3,respectively.4.The tail feather growth of QYM and TNM subtypes during the age of 0-11weeks old were obtained.The results show that the growth rate was highest in L1,followed by L2,L3,L4,L5,and L6.5.The feather maturity of primary feathers,the first feather maturity of late-feathering cocks in QYM and TNM were observed during the age of 4-11 weeks old.The results show that the maturity of primary feather in L1,L2 and L3 chickens was better than that in other types,while it was poor in the noneruption L6 type.This phenomenon is related to the speed of the feather maturity.6.The correlation coefficient of primary feathers of with body weight in QYM and TNM cocks was higher than that of tail feather with the body weight.This study explored the growth of primary feather,primary coverts,and tail feather,primary feather maturity and body weight in various subtypes of late-feathering from different genotypes.The subtypes with excellent feather growth,maturity of feather and weight gain were proposed,which provided a scientific basis for the phenotye precise breeding of the late feathering in Qingyuan partridge chickens.