Genome-Wide Association Analysis Of Blood Biochemical Components In Chinese Holstein Cows

Chinese Holstein cows,as the main breed of dairy cattle in China,have important economic status and development prospects.Blood biochemical components mainly include various blood cells,hormones and ions in the blood,which are of great significance in maintaining various physiological activities of cows,promoting production and preventing and treating diseases.With the rapid development and application of genome-wide association analysis?GWAS?,the research on important economic traits of livestock and poultry has reached a peak.In order to better explore the change mechanism of blood biochemical components of Holstein cows in China,we will analyze the common factors affecting blood biochemical components of Holstein cows in China,such as Parity,Age and Days in Milk?DIM?,and conduct genomic association analysis of major biochemical components to explore the genetic mechanism behind them.At the same time,to avoid false positive results of genome-wide association analysis,an optimization algorithm-Farm CPU algorithm was used.In this study,1226 cows from Holstein dairy cow breeding base in south China were selected for sampling.Three serum hormones were selected for traits:Insulin?INS?,Triiodine-thyrogenine?T₃?and Tetriodine-thyrogenine?T₄?;The ions in the five serums are calcium(Ca²⁺),sodium?Na⁺?,potassium?K⁺?,chloride?Cl^-?and magnesium(Mg²⁺);And 13 blood routine indexes,white blood cell count?WBC?,red blood cell count?RBC?count,hemoglobin?HGB?,RBC deposited?HCT?,large proportion of platelet?P-LCR?and platelet volume distribution density?PDW?,neutrophil percentage?GRAN?,lymphocyte count?LYMF?,platelet count?PLT?,the average content of red blood cells,hemoglobin?MCH?,mean red cell volume?MCV?,mean platelet volume?MPV?,the average red blood cell hemoglobin concentration?MCHC?.The variance analysis was carried out with the litter,age and days of milk production of Holstein cows in China as variables,and the whole genome scan was carried out on all cows tested to obtain genotype data.After quality control of all the data,a total of 47,396SNPS were obtained from 1216 individuals.According to the analysis of the results,with the growth of gestation and age of Holstein cows,the contents of T₃and T₄ in the group with high gestation and old age were significantly lower than those in the other groups?P<0.05?,and the overall trend was downward;As the number of days of milk production increased,the concentrations of Ca²⁺,Na⁺,K⁺,and Cl^-decreased,and the concentrations of Mg²⁺increased.Moreover,there was a significant difference in the concentrations of Cl^-and Na⁺between cows with and without milk production?P<0.05?;Although the changes of fetal number,age and lactation days of cows were not significant on most blood routine indexes,they had a great influence on the related indexes of red blood cells and white blood cells.For genome-wide association analysis of blood components,of the 19SNP sites significantly correlated with serum hormone content,10 were related to INS,5 were related to T₃,and 4 were related to T₄.DGKB was used as a candidate gene for indirect control of INS concentration;Of the 7 SNP sites significantly correlated with the concentration of ions in serum,5 were correlated with the concentration of Ca²⁺,and 2 were correlated with the concentration of Cl^-.GATA2 gene and SCN5A gene located on chromosome 22 were identified as potential candidates for Ca²⁺concentration.Farm CPU algorithm showed fewer false-positive sites in the hormone and ion traits in the serum of this study,but a large number of false-positive sites appeared in the analysis of blood routine traits.