| Mongolian cattle originated in the Mongolian plateau region,is an indispensable source of milk and meat for local herdsmen,and has great draught ability,strong endurance,and good breed that can bear hardships and endure hardships.Xilingol grassland has a temperate continental climate in the north of China.Its main climatic features are wind,drought and cold.The average annual temperature in Xilingol League was 3.4℃,and the cold period lasted for 7 months.The lowest temperature was 42.4℃in January.Under such extensive and primitive feeding conditions,Mongolian cattle can still survive normally,reproduce and have excellent genetic stability.Therefore,Mongolian cattle can adapt to extreme conditions such as severe cold weather and pure natural grazing on the grassland.In this study,using Mongolian cattle as experimental animals,the selection between Mongolian cattle and Mongolian cattle Charolai hybrid white cattle was studied by gene chip,the copy number variation of the whole genome of Mongolian cattle was analyzed,the blood biochemical indexes of Mongolian cattle with horn or without horn were studied,and the meat quality of Mongolian cattle in different body conditions was measured.The study mainly included four experiments,and the research contents and results of each experiment were as follows:Experiment I.Comparison of Blood Physiological and Biological Indexes of different breeds of horned and hornless cattle in Inner MongoliaDuring the heat stress period in summer,60 adult cows of three breeds(Ujimqin white cattle,Simmental and Mongolian cattle)were randomly selected from West Ujimqin Banner of Xilingol League in Inner Mongolia Autonomous Region,with similar grazing health,age and body condition.There were 20 cows in each breed(10 horned cows and 10 non-horned cows)as experimental cows.All cows were free to eat forage and drink freely.Enzyme linked immunosorbent assay(ELISA)was used to detect the content of the above indexes.The GYI-LRH-400-D biochemical incubator and BIO-RAD680 microplate reader were used to detect the content of immune,antioxidant indexes,blood biochemical indexes,sodium ion(Na~+),chloride ion(CL~-),potassium ion(K~+).The results showed that the serum Ig A,Ig G and Ig M levels of Simmental and Mongolian cattle were significantly higher than those of Ujimqin white cattle cattle,indicating that the immune function of Simmental and Mongolian cattle was better than that of Ujimqin white cattle cattle.The antioxidant capacity of horned cattle was better than that of non-horned cattle of the same breed,and the immune function of horn ed cattle was better than that of non-horned cattle of the three breeds.Under the same grazing condition,the body resistance to heat of horned cattle may be better than that of non-horned cattle.Horns have a certain promoting effect on body heat dissipa tion,and may have better adaptability to the local environment,stress resistance and tolerance to roughage are better than those of non-horned cattle.Experiment II.Study on meat quality characteristics of Mongolian cattle with different body conditionsTwenty-four healthy adult Mongolian cattle castrated bulls,about 3 years old,were randomly selected as experimental cattle in the family ranch of Sunite Left Banner,Xilingol League,Inner Mongolia during the winter.The experimental cattle were grazed naturally all year round and were free to forage and drink freely without supplementary feeding in winter.A 9-point scoring scale was used.They were divided into three groups according to body condition score,with 8 as high group(FC),7 as standard gro up(SC),and 6 as low group(TC).After slaughter,the longissimus dorsi muscle was harvested for determination of nutrients,minerals,amino acids,and fatty acids.The results showed that the content of human essential amino acids in the muscle of Mongol ian cattle with different body condition scores was better than the ideal protein pattern prescribed by FAO/WHO,and it belonged to high quality protein food.The content of monounsaturated fatty acids in the meat of Mongolian cattle in the high group was slightly higher than that in the normal and low groups,and the content of polyunsaturated fatty acids in the meat of Mongolian cattle in the low group was significantly higher than that in the high and normal groups.There was little difference in MUFA/SF A ratio among the three groups of Mongolian cattle.Mongolian cattle in the high score group had dark red muscle color,normal p H,strong water holding capacity and high cooked meat rate.Experiment III.Genome-wide selection signal analysis in Mongolian cattle.Fifty Mongolian cattle with similar age,weight,and the same number of males and females were randomly selected from family pastures in the Hulunbuir and Xilingol grasslands in Inner Mongolia,and 22 Ujimqin white cattle were randomly selected fro m the Ujimqin white cattle population,for a total of 72 cattle.Growth traits were recorded and blood samples were genotyped using Gene Seek Genomic Profiler High-Density(GGP HD 150K).The resulting genotyping results were subjected to selection signal analysis.The results showed that the whole genome selection signal detection of Mongolian cattle was constructed using the Fst method using the bovine SNPs microarray genomic data.A total of 553 significant loci were obtained,and 143 genes were annotated in these selected segments.The selected genes were mainly related to hair color,hair follicle,bone and muscle growth,reproduction,and other traits.In this study,genes associated with cattle production traits were identified:GABRB1,ZNF410,BLCAP,ZFAT,EFR3A,XKR4,TOX,and SNX29.Genes such as GABRB1,PPP3CC,NCOA,and SERPINA5,which affect important economic traits such as reproduction,overlap with the selection signal loci described above.Experiment IV.Whole-genome copy number characteristics analysis of Mongolian cattleUsing the typing data obtained in experiment 4,CNVRuler was used to stitch the CNV of each individual in the Mongolian cattle population into CNVR before using PennCNV to infer CNV(copy number variation)of the typing data.T he assembled CNVR was verified by q PCR.CNVR was annotated by Bio Mart in Ensembl website,and Gene function enrichment analysis was analyzed in The Gene Ontology Resource website(http://geneontology.org/).To map the whole genome variation of Mongolian cattle.Based on Geneseek Genomic Profiler High Density(HD)150K SNP array,a total of 334 CNVR with a length of 65.19Mb were identified in the Mongolian cattle genome.It accounts for about 12.60 of the genome size(UMD 3.1).The number of CNVR on each chromosome ranged from 7 to 21,with chromosome 8 being the least and chromosome 5 the most.The proportion of CNVR length in chromosome length was between 0.35%and 6.19%,chromosome 27 accounted for the least,and chromosome 26accounted for the most.The 334 CNVR were reproduction traits,production traits,carcass and meat quality-related traits,milk-related traits,external characteristics-related traits,and disease-related traits.Among the 334 CNVR,a total of 661 genes were annotated.Gene functional enrichment analysis revealed a series of potential molecular mechanisms underlying the environmental adaptability of Mongolian cattle.The copy number variation whole genome map of Mongolian cattle was constructed. |
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