Study On The Milk Fatty Acid Variability Of Chinese Holstein And Correlation Analysis For Genes Related To Fatty Acid Synthesis

The research used323Chinese Holsteins in Experimental Farm of Yangzhou University as research object to determine milk fatty acids by Gas Chromatography(GC).The effect of season,parity,milking period and mastitis on milk fatty acids was analysed by general linear model.PCR-SSCP and sequencing were applied to analyze the single nucleotide polymorphisms of milk fatty acid synthesis genes such as stearoyl-coenzyme A desaturase1(SCD1), fatty acid synthase (FASN) and diacylglycerol acyltransferase1(DGATI).The correlation between the different genotypes and milk fatty acid composition was analyzed by general linear model. The main results are listed as follows:(1)21fatty acids can be found out by Gas Chromatography,the total content was about22.86mg/mL. Ratio among SFA, MUFA and PUFA was about63:28:9, and ratio among sc-FA,mc-FA and lc-FA was about4:10:86.(2)Season had great significant effect on total fatty acid content,fatty acid saturation and length of carbon chain (P<0.01).Parity had great significant effect on total fatty acid content (P<0.01), significant effect on length of carbon chain (P<0.05),and no significant effect on fatty acid saturation. Milk fatty acids of mid-lactation stage and late-lactation stage had no significant difference on fatty acid content,but significant difference on fatty acid saturation and length of carbon chain (P<0.05). Mastitis had significant effect on total fatty acid content (P<0.05), but no significant effect on fatty acid saturation and length of carbon chain.(3)2SNPs of SCD1gene were found in exon5:g.10329C>T,and g.10213T>C,both of them were in Hardy-Weinberg Equilibrium status,the mutation of10329changed from Ala to Val.The fatty acid content of TT genotype was more than that of CC genotype, TT genotype significantly decreased the relative content of MUFA (P<0.05),and was significant negatively correlated with the unsaturation index (P<0.05)(4)There was1SNP of FASN gene in exon34(g.16009A> G) which was in Hardy-Weinberg Equilibrium status.The total fatty acid content of AA genotype was higher than AB and BB genotypes,but sc-FA content was lower.This mutation has no significant effect on fatty acid saturation,but sc-FA%of AA genotype was significantly lower than that of BB genotype (P<0.05)(5) There was1SNP K232A of DGAT1gene in exon8,the double base mutation from AA to GC took place at10433and10434bp, which made the change from Lys to Ala, in Hardy-Weinberg Equilibrium status.This mutation had no significant effect on fatty acid content and the relative content.