| Xichuan Black-bone chicken originated in Xichuan country of Henan province,was only a white(katabane)feather color and produced blue shell eggs.In order to effectively conserve and utilize the superior genetic resources,it was necessary to study the crossbreeding effect and the genetic diversity.Three combinations(Xichuan Black-bone♂ × Yellow Shank Silky chicken ♀(XY),Xichuan Black-bone♂×Black Shank Recessive White♀(XG)and Xichuan Black-bone×Xichuan Black-bone(XX))were employed as materials in this research,35 cocks and 100 hens at hatch were selected from each combination and all chickens were fed under the same raising condition for 35 weeks.During the 35 weeks,hatching performance,growth performance,slaughter performance,meat quality and muscle fiber characteristics were measured and analyzed to evaluate the effect of hybridization.Furthermore,in order to determine the origin and genetic diversity of Xichuan Black-bone chicken,the hypervariable region I sequence variations in mt DNA D-loop and calculated haplotype diversity,nucleotide diversity and genetic distance were analyzed.The main results were as follow.(1)Hatch performance Egg weight of XG were the biggest,while XX was the lightest in the three combinations(P<0.05).Fertilization rate,fertilized eggs hatching rate and birth weight of XG was the highest,which reached the 92.7%,81.7% and 33.0g,respectively,healthy chick rate was 100%.(2)Appearance feature At one-day-age,XX was not completely black skin and black shank,possibly because it contained less proportion of heterozygote.XY could not sex discrimination by appearance,because hybrids appeared black shank,yellow shank,black skin,light skin.For 16-week-old XY chicken,appearance of 85.2% cock were yellow shank and light skin,while the appearance of yellow shank and black skin and black shank and skin were 6.9%.For F1 hens,54.1% hens were black skin and black shank,black shank and light skin,black shank and Shallow black skin were 17.6%,the rest 10.7% was yellow shank and black skin.All of the XG chicken were black skin and black shank.(3)Growth performance In 16 weeks,average weight and growth rate of two hybrid chicks were bigger than those of the XX chicks,and those of the XY group was the largest.The growth curves of three combinations of 16 weeks old were analyzed and fitted with three kinds of non-lineared models.For the XY and XG chicks,Von-Bertalanffy,Logistic model had better effect on fitting with the growth curves,respectively.The growth inflexion on body weight and age was(531.0g、7.7 weeks)and(567.5g、9 weeks).(4)Body measurement,carcass traits Shank length,keel bone length,shank girth of two hybrid chicks were significantly higher than those of XX chicks(P<0.05),and XY chicks were the largest.Rate of chest muscle of XX cocks was significantly higher than that of XY cocks(P<0.05),however,body weight at slaughter,carcass weight,semi-eviscerated weights,eviscerated weights,leg and breast muscle weight of XY and XG groups were significantly higher than those of XX group(P<0.05).(5)Meat quality traits p H value 45 min post mortem of chest muscle in XY female chicks was higher than that of XX chicks,while that of leg muscle in XY male chicks was significantly higher than that of XY chicks,for other meat physic and chemical characteristics,there was no significant difference between three groups.There were significant differences in Muscle fiber diameter and density among the hen of three combinations(P<0.05).Overall,the XG chicks has the least muscle fiber diameters and the largest muscle fiber density except leg muscle in cock.(6)Egg quality The egg weight of two hybrid F1 chicks were significantly higher than that of XX chicks(P<0.05),yolk weight and yolk color of XG chicks were significantly higher than those of XX chicks(P<0.05),albumen height and Haugh unit of XX were significantly higher than those of XG chicks,percentage of shell and yolk were higher than those of XG chicks(P<0.05).There were no significant differences in shell weight,shell thickness,egg-shaped index in different combination.(7)Xichuan Black-bone chicken genetic diversity To determine the origin and genetic diversity of Xichuan Black-Bone chicken,its hypervariable region I sequence variations in mt DNA D-loop was analyzed and align with the available chicken sequence in Gen Bank.The results showed that,in mt DNA D-loop of Xichuan Black-bone chicken the 21 mutation sites and 10 haplotypes were found.Haplotype diversity was 0.867 and nucleotide diversity was 0.00882.The genetic distance and the NJ phylogenetic tree obtained by Mega 5.1 software,the genetic distance ranged from 0.0019 to 0.0235,the average genetic distance of haplotypes was 0.0140±0.0031.All of the samples were clustded in 4 clades.In a word,it could be conclude that the genetic diversity was relatively rich and wealthy and there were 4 maternal origins to Xichuan Black-bone chicken population.To sum up,the F1 chicks of XG group in incubation performance,growth performance,carcass quality,egg quality had obvious advantage than those of XX and XG chicks,and the genetic diversity of Xichuan Black-bone chicken was especially rich by mt DNA D-loop sequencing.This provides a basis for conservation and utilization of of Poultry Genetic Resources of China. |
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