| Xichuan Silky is a famous local special breed in China,and was the only kind of white(katabane)feather colour Silkys producing blue shell eggs.Studies showed that melanin deposition and fatty acid content in Silky fowl could affect meat quality,of which the melanin deposition is the most important influence factor,and it can increase significantly the nutritional level and flavor by improving melanin content.In order to dig deeper the potential value of melanin in Xichuan Silky,exogenous additive was used to regulate content of breast muscle melanin and increase its nutritional level.In this paper,Xichuan Silky was fed with six different dietary tyrosine levels at 0-12 weeks,and the specific grouping and addition levels were control group(0%),treatment group I-V(0.2%,0.4%,0.6%,0.8%,1.0%).Slaughtered at 12 weeks,growth traits,slaughter traits and meat quality measured.And the differential genes among the samples were screed using high-throughput transcriptome sequencing,and analyzed with the Go gene function and KEGG pathway enrichment.By combining the apparent data with molecular markers,aim to identify differential genes related to melanin and fatty acid,and establish a solid foundation for high quality Silky fowl.The results of this study are as follows:Study 1: Effect of dietary tyrosine levels on growth traits and slaughter traits of Xichuan Silky1.Growth performance: The body length in treatment V was significantly lower than that in treatmentⅠ,Ⅳ(P<0.05).The keel length in treatment V was significantly lower than that in the remaining five groups(P<0.05).The shank length in treatment Ⅰwas significantly higher than that in treatment Ⅲ,Ⅴ(P<0.05).The breast width and chest angle in treatment V were significantly lower than that in control group and treatment Ⅰ(P<0.05).2.Slaughter traits: The live weight in control group and treatment Ⅰwas the highest significantly(P<0.05).The slaughter rate in treatment Ⅳ,Ⅴwere significantly lower than that in the remaining four groups(p<0.05).The leg muscle weight in treatment Ⅲ,Ⅳ were significantly lower than that in control group(P<0.05).However,there were no significant difference between the breast muscle rate and eviscerated yield rate(P<0.05).Study 2: Effect of dietary tyrosine level on meat quality of Xichuan Silky1.Meat quality: The leg muscle shear force in treatment Ⅱwere significantly higher than that in the remaining four treatment groups(p<0.05).The pectoral muscle shear force in treatment Ⅱ,Ⅴ were significantly higher than that in control group(p<0.05).But the breast and leg muscles p H were no significant difference among all groups(p<0.05).2.Melanin content: It can increase significantly the deposition of melanin in breast muscle by different dietary tyrosine levels.The deposition of melanin in breast muscle in treatment Ⅱ~Ⅴ was significantly higher than that of control group and treatmentⅠ,and it was the largest when tyrosine was added at 0.8%(treatment Ⅳ)(p<0.05).3.Fatty acid content: Based on the results of the previous melanin assay,the fatty acid content in control group and treatment Ⅳwas tested and 19 amino acids were detected.The content of docosanoic acid in treatment Ⅳwas significantly lower than that in control group in saturated fatty acids(P<0.05).The content of linoleic acid in treatment was significantly lower than that in control group in unsaturated Ⅳfatty acid(P<0.05).The other 17 fatty acids were no significant difference in the two groups(P<0.05).Study 3: Identification of genes regulated by dietary tyrosine level which related to meat quality in Xichuan SilkyBased on the results of the previous melanin assay,breast muscle tissue in control group and treatment group IV was used for high-throughput transcriptome sequencing.The results showed that 14935 genes were expressed in two samples,of which 13477 genes were co-expressed in two samples,698 genes were specifically expressed in the control group,and 760 genes were specifically expressed in the treatment Ⅳ.Finally,417 differentially expressed genes were obtained,of which 160 genes were up-regulated in treatment IV and 257 genes were up-regulated in the control group.Differential genes were analyzed by GO function and KEGG enrichment,and annotated to 50 GO term and 91 KEGG pathways.12 pathways related to fatty acid metabolism and 4 pathways related to melanin synthesis were screened.Additionally,FAS,ACACB,MITF and TYRP2 genes related to fat deposition and melanin synthesis were found,and intended to be the focus of follow-up research. |
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