| The aim of this study was to explore the effects of exercise’s amount on carcass composition,meat quality,and m RNA expression profiles in breast muscle of Huainan female chicken,as well as analyze of two candidate genes related to exercise traits in 5 chicken breeds.300 female Huainan chickens(60-day-old)with similar body weight were selected and raised in the same environment house,with a density of 8 animals per square meter indoor,and the chickens could easily access the outdoor area(3 birds/m2).Daily steps were counted by pedometer for all birds from 61 to 140 days of age.At 140 D of age,based on the average daily step count ±1 SD,birds were divided into three groups: high number of steps(HS:24608 ±1270),medium number of steps(MS:20438 ±950),and low number of steps(LS:16935 ±1119).15 birds from each group were selected to determine of slaughter performance and meat quality.Moreover,four pectoralis major muscle samples from the HS and the LS group,respectively were used to RNA-seq analysis.In addition,60 female chickens from 5 breeds,respectively,including Huainan,Tianchang,Fengda layers,Royai,and Ross 308 were used to analysis of polymorphism of the two candidate genes that association with exercise trait.The results show that the body weight of the HS group was heavier than that of the MS and LS group 240.4g and 326 g,respectively(P<0.05).the percentage of breast muscle weight was lower in the HS group when compared with the LS group(P<0.05).There were no significant differences in dressing percentage,the percentage of partially eviscerated carcass,full eviscerated weight,and the percentage of leg muscle weight among the 3 groups(P>0.05).The shear force,dripping loss,and cooking loss of HS group were lower than LS group 18.1%,29.2%,and 11.1%,respectively(P<0.05).The a* value of the HS group was greater than that of the MS and LS group(P<0.05).There were no significant differences in IMF and PH among 3 groups(P>0.05).By using a P-value < 0.05 and log2 |foldchange| > 1 as the cutoff,a total of 150 differentially expressed genes(DEGs)were identified from the pectoralis major muscles of the HS and LS group.59 genes were up-regulated and 91 genes were down-regulated in the HS group when compared with the LS group.These DEGs are mainly enriched in GO terms related to “skeletal muscle development”.From the top 10 genes with the great changes in expression levels,we selected ASB2 and ANKRD2 as candidate genes for exercise trait,science both of them have well-established biological functions in exercise.A synonymous mutation(16338,C>T) was found in exon 3 of ASB2 gene.The polymorphism information content of Huainan chickens and Tianchang chickens was 0.33,which were not in Hardy-Weinberg equilibrium state(P<0.05).Fengda layers,Royai chickens and Ross 308 chickens were in Hardy-Weinberg equilibrium state(P>0.05).Moreover,a synonymous mutation(2477,T>C)was found in exon 8 of ANKRD2 gene.The polymorphism information content of Tianchang and Huainan chickens was 0.12 and 0.13,which were in Hardy-Weinberg equilibrium state(P>0.05).The polymorphism information content of Ross 308 chickens was 0.18,which was not in Hardy-Weinberg equilibrium state(P<0.05).The polymorphism information content of Royai and Fengda layers were 0.In summary,our results suggested that exercise can enhance the growth of Huainan female chicken,but reduce the percentage of breast muscle weight,and has no significant effect on other carcass parameters.Meanwhile,more exercise can also improve tenderness and water holding capacity of chicken.The differentially expressed gene of breast muscle in different exercise levels are mainly related to skeletal muscle development.In addition,he exon 3(13668,C>T)of ASB2 gene of Tianchang Yellow chickens,Huainan chickens,Fengda layers and Royai chickens are medium degree polymorphism,and Ross 308 chickens is low degree polymorphism,However,the exon 8(2477,T>C)of ANKRD2 gene of five different chickens were low degree polymorphism. |
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