The Law Of Growth Of Chicken And The Association Of PGC-1α Gene With Meat Quality Of Chicken And Expression Level Of Three Genes Relation To Myofiber Type

Selecting a local breed Qingyuan Patridge Chicken （QPC） and a introduced breed from abroad Recessive White Chicken （RWC）, we created fit growth curves for body weight and tibia length by three modles, such as Logistic, Gompertz and Von Bertanlaffy, and choosed the best models for body weght and tibia length respectively via comparing fitting effects of this three models. We detected their intermuscular fat content （IMF）, shear force values and ratio of water losing （RWL） of pectoralis. Screening polymorphism points of PGC-1a gene （peroxisome proliferators activated receptor gamma coactivator-1alpha） which is the significant factor of affecting meat quality, we have foud some SNPs having important impact on meat quality. Describing the regular pattern of PGC-1αgene with three isoforms of myosin heavy chain MyHC gene （FWM gene, FRM gene and SM gene） relevant to myofiber type, we analyzed the relationship among PGC-1αgene with FWM gene, FRM gene and SM gene. The main results are as follow:1. In this three models used for fitting growth curves, Von Bertalanffy model is the best to fit growth curve of body weight for0-4weeks RWC, and Gompertz model is the best for5-14weeks RWC and0-14weeks QPC. Logistic mode is the best to fit growth curve of tibia length for0-14weeks RWC and QPC.2. Inflection points of Gompertz model for body weight of RWC （cocks and hens） and QPC （cocks and hens） are in8.6weeks,8.6weeks,8.5weeks and9.0weeks respectively. Inflection points of Logistic model for tibia length are4.2weeks,4.0weeks, 4.2weeks and3.6weeks. There are no significant differences respectively for body weight and tibia length bwtween different breeds and genders. The maxium weitht weekly gain of RWC is about100g higher than of QPC.3. Body weight of2weeks is extremely significantly related to that of3-14weeks, and R2value is0.8. Tibia length of3weeks is also extremely significantly related to that of3-14weeks, and R2value is0.8. In this point, we can pick out those chickens which will have higher body weight via sorting chickens out which have higher body weight and longer tibia length in early stage.4.13SNPs of PGC-1a gene has been foud by screening13exons and some intron of the gene using the method of PCR-SSCP with direct sequencing and comparing the sequences with the gene of Genbank （Accession:NW₀01471687）. The SNPs are:SNP0（G5407189A）, SNP1（G5368254A） with SNP2（C5377373T）, SNP3（C5405129T）, SNP4-1（T5406152C）, SNP4-2（A5406203G）, SNP5（G5407235A）, SNP6-1（C5411336T）, SNP6-2（A5411345G）, SNP8（A5419140G）, SNP13（G5420542A）, SNP14（T5420953C） and SNP15（G5430392A）. SNP0, SNP2, SNP3, SNP4-1, SNP6-1, SNP6-2and SNP8are in exions and silent mutation. SNP4-2, SNP5and SNP15which are in exons respectively results in the mutations of amino acids R173G, D216N, and R673H. SNP1, SNP13and SNP14are in introns.The genotypes distribution of all the SNPs of RWC and QPC meet the law of Hardy-Weinberg Equilibrium （P>0.05）. The differences of genotypes distribution between RWC and QPC at these SNPs are extremely significant excpt SNP8. The dominant allel of each SNPs are the same in the two breeds. The average of PIC of RWC and QPC are0.088and0.133respectively, which belong to low-degree polymorphism points.5. The analysis on meat quality of RWC and QPCThe differences of IMF, shear forces and RWL of pectoralis between cocks and hens of RWC7weeks aer non significant. The shear force of RWC cocks17weeks is extremely significant higher than of hens, WLC of cocks extremely significant lower than of hens, and there is no significant variance between sexes as to IMF. Shear force of cocks for QPC is higher than hens extremely significant, and IMF and RWL between sexes diverge with no significance.IMF of RWC17weeks is higher than of7weeks extremely significant, and shear force and RWL lower than of7weeks extremely singificant. IMF of QPC17weeks is lower than of RWC7weeks extremely, significant, but the difference value is not large. Shear force and RWL of the former are lower than of RWL7weeks extremely significant. IMF and shear force of QPC17weeks are significant lower than17weeks RWC, and no significant difference of RWL between QPC and RWC is found.6. The association analysis of SNPs with meat quality shows that SNP0、SNP1、 SNP2、SNP4-2、SNP5and SNP15have some impact on meat quality, but not SNP3、 SNP4-1、SNP6、SNP8、SNP13and SNP14.SNP0has significant impact on shear force of7weeks RWC. The value of AA genotype is lower than of AG and GG genotypes compeletly significantly. There are no singficant differences between genotypes within other genders of populations.The third-order interaction of SNP1, breeds and genders have significant impact on ratio of water losing. But variance of ratios of different genotypes is not significant in respective breeds and genders.SNP2has significant impact on IMF. The value of CC genotype is higher than of CT genotype significantly. This SNP also affects ratio of water losing of hens of QPC, and the value of CC genotype is higher than of CT genotype extremely significantly.The third-order interaction of SNP4-2, breeds and genders have significant impact on ratio of water losing. But variance of ratios of different genotypes is not significant in respective breeds and genders.SNP5has extremely significant impact on ratio of water losing of7weeks RWC. The values of AA and AG genotypes is extremely significantly higher than of GG genotype, and the value of AG genotype is significantly than of GG genetype. There is no significant difference between AA and AG genotypes. This SNP also has extremely significant influence on ratio of water losing of17weeks QPC, and the value of AA genotype is significantly higher than of AG and GG genotypes. Significantly difference of ratio of water losing between genotypes in17weeks RWC is not foud.SNP15has extremely significant impact on shear force. The value of AA genotype is extremely significantly lower than of AG and GG genotypes. There is no significant variance between shear force of AG and GG genotypes.7. The variable trends of PGC-1a gene expression levels in myocardium, pectoralis and gastrocnemius with weeks are the same between different genders, but not same between different breeds. The expression level of PGC-1α gene in gastrocnemius of QPC and RWC increases from0th week to2th week, and remains unchanged from2th week to10th week, and then pick up again to the beginning level from10th week to12th week. The upward amount of RWC is larger than that of QPC. The trends of FWM and FRM gene look like a "U" word. The expression levels of FWM and FRM are both higher in the early phase, and downward to the lowest at8th week, and rise a bie from then to the later phase. There is no some regular patterns about the change of expression level of SM gene, except the lowest level at8th weeks also.8. For cocks of RWC, PGC-1a gene expression level in gastrocnemius negatively correlate to FWM gene expression level extremely significantly, and positively correlate to FRM gene expression level extremely significiantly. The correlation coefficients are-0.719and0.748respectively. For hens of RWC, PGC-1α gene expression level in gastrocnemius negatively correlate to FWM gene expression level extremely significantly, and positively correlate to FRM gene expression level extremely significiantly. The correlation coefficients are-0.631and0.694respectively. There are no significant correlations between expression level of PGC-1α gene and SM gene in the two genders of RWC. The relationships of PGC-1α gene expression level to expression level of FWM gene, FRM gene and SM gene are not found.