【目的】探讨中国南方地区荷斯坦牛SCD1基因外显子5遗传多态性及其对乳中不饱和脂肪酸含量及其不饱和指数的影响。【方法】以扬州大学实验农牧场323头中国荷斯坦牛为试验材料，采用PCR-SSCP法对SCDI基因外显子5的3个位点遗传多态性进行分析，同时挑选140头体况相近（BCS=3．0±0．5）、无临床乳房炎、胎次在2-3胎、处于泌乳中后期（产奶100--300d）的中国荷斯坦牛，取全天混合奶样（早：中：晚=4：3：3）100mL用于测定脂肪酸含量，进而分析多态性对乳中脂肪酸成分的影响。【结果】SCD1-702位点无多态，SCD1-762和SCD1-878分别发现T／C和C／T两个突变。SCD1-762位点A为优势等位基因，基因频率为0．7897。SCD1-878位点C为优势基因，频率为0．7835。χ2检验表明该群体的中国荷斯坦奶牛在SCD1基因的这两个位点都处于Hardy-Weinberg平衡状态（胗0．05）。SCD1-762与SCD1-878处于极显著连锁不平衡，连锁不平衡系数，2为0．879，达到极显著水平（P〈0．01）。SCD1-762和SCD1-878两位点共组成4种单倍型：AC、BC、AT、BT。SCD1-762、SCD1-878及其单倍型对MUFA比例及总不饱和指数的影响均达到显著水平（P〈0．05），即SCD1878位点TT型乳中MUFA比例及总不饱和脂肪酸指数显著低于CC和CT型，而SFA比例显著高于CC和CT型（P〈0．05）；SCD1762位点BB型乳中MUFA比例及总不饱和脂肪酸指数显著低于AA和AB型（P〈0．05）。单位型AC型MUFA比例及总不饱和指数显高于BT型，而SFA比例显著低于BT型（P〈0．05）。【结论】SCD1878和762位点突变对乳中乳脂肪酸组成及饱和指数有显著的遗传效应，可作为影响中国荷斯坦奶牛乳脂肪酸组成的重要候选基因。

Objective This experiment was conducted to explore the association between SCD1gene and milking traits in Chinese Holstein in south China.[Method] The polymorphism of SCD1 gene was investigated for 323 Chinese Holstein cattle from the experimental farm of Yangzhou University using Polymerase Chain Reaction-Single Strand Conformation Polymorphism (PCR-SSCP) technique, at the same time, from 140 Chinese Holstein with similar body condition (BCS=3.0±0.5), no clinical mastitis, 2-3 parities and during lactation, 100 mL mixed milk samples a day (morning﹕noon﹕evening=4﹕3﹕3) were collected for determining the content of fatty acid, and then 100 mL mixed milk samples were collected all day (morning﹕mid-day﹕evening), which were used for determining fatty acid, and the effects of alleles on the component of fatty acids were then analyzed using a mixed animal model.[Result]Two polymorphic sites, SCD1-762 and SCD1-878, were detected with the advantageous allele&nbsp;frequencies of A at SCD1-762 and C at SCD1-878 were 0.7897 and 0.7835, respectively.χ2 test indicated that these two sites were in the Hardy-Weinberg equilibrium. Linkage disequilibrium existed between SCD1-762 and SCD1-878 (r2=0.879) at a very significant level (P<0.01). Four haplotypes were defined at the two sites, TC, CC, TT, and CT. Effect of SCD1-762, SCD1-878 or certain haplotypes was significant on the ratio of MUFA and the total saturation degree in milk (P<0.05). The ratio of MUFA and total saturation degree in milk of haplotype TC was significantly higher than CT, while the ratio of SFA was significantly lower than CT (P<0.05).[Conclusion]The two polymorphic siteshad some genetic effects on milking traits, but further researches are needed for its mechanism.

This study aimed to analyze the impact of different pasteurization temperatures and storage periods on fatty acid composition of pasteurized milk.Raw milk was pasteurized at 65 ℃ for 30 min or at 85 ℃ for 15 s,sealed and then stored at 4 ℃.The fatty acid composition of raw milk and pasteurized milk during storage was analyzed by gas chromatography.The results indicated no significant difference in fatty acid composition was present among pasteurized milks treated at different temperature(P 0.05).In addition,the fatty acid composition of pasteurized milk was quite stable during storage.However,the content of fatty acid C4:0 in pasteurized milk treated at 65 ℃ for 30 min and stored for 8 d was significantly higher than in raw milk.This might be due to the bacterial proliferation.The content of CLA declined following temperature processing and storage whereas no significant difference was found(P 0.05).This study indicated that pasteurization had no effect on the contents of characteristic fatty acids in the milk.Therefore pasteurization could be used as an effective way to produce milk rich in CLA.

This study was aimed to detect the single nucleotide polymorphism(SNPs) of Holstein cows diacylglycerol acyltransferase 1(DGAT1) gene in exon 8,and to predict the protein structure and function caused by the mutations and discuss the evolution relationship of DGAT1.PCR-SSCP combined with sequencing was used to detect the SNPs in exon 8 of DGAT1 gene.Bioinformatics approach was used to predict the physicochemical properties and structures of DGAT1 protein.The approach was also used to analyze the amino acid homology of DGAT1 between different species,and to build the evolutionary tree.The PCR-SSCP analysis results showed that a double mutations existed in exon 8 of DGAT1 gene,namely M694 and M695.The prediction of protein structure and function displayed that the double mutation had no influence on the physicochemical properties and structures of the protein,but led to the changes in the component of its protein function domain.The evolution analysis results indicated that amino acid sequence homology of DGAT1 between Holstein cows and sheep was the highest(99.1%),and the homology between Holstein cows and chimpanzees was the lowest(65.3%).

【Objective】The effect of SCD1 different genotypes on gene expression and milk fatty acid composition was studied.【Method】Three hundred and three Chinese Holstein cows of a dairy farm were used to detect the polymorphism of the exon 5 of SCD1 gene using PCR-SSCP,and the relative gene expression was assayed by quantitative FQ-PCR,the milk fatty acid composition was assayed using the method of gas chromatography.【Result】One SNP,C878T,was detected,defining three genotypes,CC,CT and TT,with frequencies of 0.617,0.339 and 0.044,respectively.The allele frequencies of C and T were,respectively,0.787 and 0.213.Only the expression of CT genotype was significantly higher than TT genotype(P<0.05).Total saturated fatty acids of TT was significantly higher than CC or CT(P<0.05).There were highly significant differences in the fatty acid C6:0,C8:0,C14:0,C15:0 and c9t11CLA(P<0.01),and significant differences in the fatty acid C4:0,C12:0,C17:0 among these three genotypes(P< 0.05)【.Conclusion】The SNP C878T of SCD1 has a great genetic effect on the gene expression of SCD1 and the content of fatty acid in milk,it could be a useful genetic marker for milking trait in Chinese Holstein breeding.

[Objective]This study aimed to analyze the change of fatty acid composition in yogurt pro- cessed with different inoeulum of lactobacillus after maturity and during storage. [Method]The milk was inoculated with2 %,3 % and 4% starter culture, respectively. The matured yogurt was sealed in 4 ℃ refrigerator during storage. The fatty acid composition of the yogurt and raw milk was tested with gas chromatography method. [Result]The result showed that: after the yogurt fermented completely, the content of short chain fatty acid C4 : 0,C6 : 0 and C8 : 0, medium chain fatty acid C12 : 0, C14 : 0, C14 : 1, C16 : 0 and C16 : 1, as well as the long chain fatty acid C18 : 3, C20 : 3, C20 : 4 and C22 : 6 had significant difference (P〈0.05) or highly significant difference (P〈0.01)between the raw milk and the yogurt with 3 different inoculation volume, and the content of conjugated linoleic acid (CLA) was also increased. The yogurt with 3 % inoculation volume had the most obviously change. The yogurt with 3 different inoculation volume had no significant change during storage. [Conclusion]The research suggested that yogurt could reduce the content of C14 : 0 and C16 : 0, which suffering people from cardiovascular diseases, and increase the content of the polyunsaturated fatty acid C22 : 6 (DHA), which was beneficial for people. The yogurt with 3 % inoculation volume was the most effective.

【Objective】The purpose of this study is to find and establish a simple and efficient method used to detect the fatty acid composition and content in the milk.【Method】Gas chromatography(GC-FID) method was used to separate the milk fatty acid composition by using the Agilent HP-88 fatty acid methyl esters capillary column and temperature programmed method,quantitative retention time was used for quantify by qualitative and peak area percentage method.【Result】The results showed that the fatty acid in milk was well separated.The recovery and precision of detection method were 99.588% and 2.600,respectively,with a high accuracy and repeatability.【Result】The experimental method could be used as a milk fatty acid detection technology for promotion and application.

Intramuscular fat (IMF) is a key parameter for evaluation of nutritional quality of beef, with its endogenous synthesis regulated by stearoyl CoA desaturase (SCD1) and diacylglycerol-acyl transferase 1 (DGAT1) genes in cattle. The object of this research was to evaluate the effect of SCD1 and DGAT1 polymorphisms on IMF trait in beef cattle and to estimate the frequency distribution of SNPs in the two genes in Chinese cattle populations. The SCD1 and DGAT1 polymorphisms were detected by PCR-single strand conformation polymorphism (PCR-SSCP) method in Chinese Simmental cattle and their associations with IMF traits were analyzed using the general linear model (GLM). The frequency distribution of SNPs in SCD1 and DGAT1 genes were detected by PCR-SSCP method and analyzed in seven other cattle populations. The results showed significant associations of SNPs SCD1-878, SCD1-762, and DGAT1 10433 and 10434 with IMF (%) and shearing force values (SFV; kg) in Chinese Simmental cattle. A haplotype combining SCD1-878C, SCD1-762T, and DGAT1 10433 and 10434-GC had the highest IMF, marbling score and shearing force. The polymorphic investigation indicated that the frequency of SCD1-878C or SCD1-762T was significantly higher in Chinese southern cattle (Leiqiong, Yunnan High pump, BMY or Minnan Cattle) than in Chinese northern cattle (Chinese Simmental, Luxi Cattle, Bohai Black or Chinese Holstein), while the frequency of DGAT1 10433 and 10434-GC in Chinese indigenous breed (Leiqiong, Yunnan High pump, BMY, Luxi Cattle, Bohai Black, or Minnan Cattle) was significantly lower than breeds with imported blood (Chinese Simmental or Chinese Holstein). These findings demonstrated that both the SCD1 and DGAT1 SNPs were prospect genetic markers for IMF traits, and the SCD1 SNPs could be used as a genetic marker for southern or northern blood in Chinese cattle.

牛乳房炎是世界乳牛业的主要危害因素之一,除了影响奶牛的发情和妊娠、造成乳产量和质量下降、药品或兽医治疗费用增加外,还导致乳牛失去泌乳能力而被强制性淘汰等严重经济损失.

Fatty acid synthase(FASN) plays an very important role in fat synthesis in dairy cow.The polymorphisms of FASN gene exon 2,4,26 and 34 in Chinese Holstein population were detected using PCR-SSCP in this study.Results indicated that only one mutation was found in exon 34(g.16009A>G).The frequencies of alleles were 0.4481 and 0.5519 for A and B,respectively.Association analysis showed that g.16009A>G had significant effects on the relative amount of short-chain fatty acids.The relative amount of short-chain fatty acids for the genotype of AA,AB were significantly more than the genotype of BB(P<0.05).It provided useful information for the regulation,selecting and breeding of Chinese Holstein aiming for fatty acid.

为探索影响中国荷斯坦牛乳中体细胞评分分布规律的因素,对我国东南沿海地区9个牧场2003年—2009年118471次奶牛群体改良(DHI)测定日记录进行了分析。结果表明:乳中体细胞数(SCC)为455.35×104个/mL,体细胞评分(SCS)为3.66。胎次、泌乳月和产犊季节显著影响乳中SCS的分布。随着胎次和泌乳月的增加,高SCS所占比例也逐渐增加,第3胎以上和第9泌乳月以后的奶牛有20%以上乳中SCS均高于6分(即大于56.5万个/mL)。春季产犊高SCS(≥6)所占比例最小(17.63%),夏季产犊比例最大(20.28%)。

【Objective】 The objective of this study was to investigate the correlation between the SCC and the amount and composition of fatty acids in milk of Chinese Holstein 【Method】 Mixed milk samples were collected in the morning,noon and at night from 121 Chinese Holstein cows that free of clinical mastitis,and the parity was two or three,day in milk was from 100 to 300.The amounts of fatty acid of milk were determined by gas chromatography.The effects of SCS on fat percentage and fatty acid composition of milk were analyzed by one-way ANOVA.The SPSS software was used to analyze SCS and milk fatty acids composition of correlation and regression.【Result】 Twenty-one fatty acids which are from C4 to C22 can be found out.Season had significant effects on the quantity and composition of fatty acids(P<0.05),and the milking stage had minor effects on the quantity and composition of fatty acids.The effects of SCS on fat percentage and the amount of fatty acids were significant at 0.05 except eight fatty acids(C14:1,C16:1,C17:0,C18:0,C18:2n6c,C20:0,C20:3,C20:4 and PUFA).With the increasing of SCS in milk,fat percentage,the amount of total fatty acid,SFA,MUFA,short chain FA,medium chain FA and long chain FA were decreasing.The SCS showed no significant effects on the relative amount of twenty-three FA including SFA,MUFA,PUFA,short chain FA,medium chain FA and long chain FA except four low content of FA(C11:0,C20:0,C20:3 and DHA).SCS a showed significant negative relationship with the amounts of SFA,MUFA,short chain FA,medium chain FA and long chain FA(P<0.05),and a significant positive relationship with the relative amount of PUFA and long chain FA.SCS showed a significant negative relationship with the relative amount of SFA,short chain FA and medium chain FA(P<0.05).Logarithm equations were optimum for the amount of total FA,SFA,MUFA,short chain FA,medium chain FA and long chain FA depending on SCS,and the fitness of the equations were above 0.9.Exponent equations were optimum for the relative amount of SFA depending on SCS,and the fitness of the equations were also above 0.9.The fitness of other equations with the relative amount of FA depending on SCS were below 0.9.【Conclusion】These results have provided a useful foundation for the prediction and evaluation of FA through SCS.

The objective of this study was to investigate the effects of clinical mastitis and pathogen-specific mastitis on the test-day milk performance and the variation of SCC for Chinese Holstein.Clinical mastitis and sub-clinical mastitis were indentified using CMT method from 140 milking cows in a dairy farm,Jiangsu Province.In September,2009,and the pathogens were indentified for the quarters of sub-clinical mastitis cow.The effects of clinical mastitis and pathogen-specific sub-clinical mastitis on the test-day milk performance and the variation of SCC were estimated by ANOVA.The proportion of clinical mastitis and sub-clinical mastitis cows were 10.00% and 51.10%,respectively.In the sub-clinical mastitis cows,the most events was the mixed infected by Escherichia coli and Streptococcus spp(26.00%),following was Streptococcus spp(23.30%).The proportion of cows infected by only one pathogen was 36.11%,and the proportion of cows infected by more than two pathogens was 61.11%.The effects of mastitis on test-day milk yield,lactose percentage,SCC and SCS were significant at P0.01 level.The test-day milk yield and lactose percentage for clinical mastitis and sub-clinical mastitis cows were less than that for healthy cows,and the SCC were higher than that in healthy cows.The pathogen types significantly affected SCC and SCS of cow.The test-day milk yield for sub-clinical mastitis cows infected by more than two pathogens were significant less than that in cows infected by only one pathogen,and the SCC were significant higher than that in cows infected by only one pathogen.The effect of mastitis on the variation of SCC was significant at P0.01 level.The healthy cows had higher ability to maintain low SCC in milk,and the possibility having more SCC for sub-clinical mastitis cows was increased.The pathogens types had no significant effect on the variation of SCC.The results indicate that the sub-clinical mastitis infected by more than two pathogens have more serious effects than sub-clinical mastitis infected by only one pathogen on the test-day milk yield and SCC in milk.These findings provide dairy producers with more information in which pathogen-specific sub-clinical mastitis cases should receive treatment and how to manage these cows.

This experiment was conducted to study the effect of SCD1 gene.To explore the effect of genetic variance in SCD1 gene on carcass and meat traits,682 cattle were selected randomly,including Chinese Simmetal cattle(Simme),Leiqiong cattle(LQ),Yunnan Gaofeng cattle(GF),BMY cattle(BMY),Minnan cattle(MN),Luxi cattle(LX),Bohai Black cattle(BH) and Holstein of South Chinese(Hols.),the polymorphism of specific fragment of SCD1 gene was analyzed by PCR-SSCP technique.A nucleotide mutation had been found at site 878,leading to an amino acid change(Glycine to Valine) at site 293,it was C878T.Three genotypes(CC,CT and TT) had been found at this site,and the frequency of genotype TT was highest in Chinese Simmetal population with the value of 0.114,and lower in Luxi cattle,Bohai Black cattle and Holstein with the value of 0.050,0.063 and 0.040,respectively.But genotype TT had not been found in the four tropic populations including Leiqiong cattle,Yunnan Gaofeng cattle,BMY cattle and Minnan cattle.The individuals with CC genotype of SCD1 showed a higher content of IMF and Mesentery fat weight traits(P0.05),but lower value of backfat thickness trait(P0.01),compared to the individuals with TT genotype.There was no significant difference among different genotypes with other traits.The results indicate that the C878T mutation of SCD1 gene has a great genetic effect on carcass and meat traits and could be a useful genetic marker for Chinese beef breeding.

本研究旨在通过DHI检测获得的体细胞数据,探讨全年中经产奶牛乳中体细胞数的变化规律。同时利用DHI中主要乳成分的数据,结合体细胞数进行相关分析,阐述体细胞数对牛奶主要成分及含量的影响,为原料奶产品质量的评估提供参考依据。对扬州某实验农牧场经产荷斯坦奶牛进行12个月(2009年4月~2010年3月)的采样,共得到2 824个DHI数据,检测数据包括:体细胞数、脂肪、蛋白质、乳糖和总固体。结果表明,乳蛋白率与牛乳中的体细胞数呈极显著正相关(P<0.01);乳脂率与SCC呈显著负相关(P<0.05),乳糖含量、总固体含量与SCC呈极显著负相关(P<0.01)。4~8月份,乳中体细胞数呈逐渐升高的趋势,并在8月份达到峰值,为350.39×104个/ml。8月份之后,体细胞数又呈下降趋势。而8月前后的两个月份,乳中平均体细胞数和体细胞数高于50×104个/ml的比例也保持在一个较高的水平。

To explore the relation of Interleukin-8 (IL8) gene polymorphism with immunity against mastitis in dairy cow, the polymorphism of IL8 gene was investigated in 610 Chinese Holstein cow from 30 bull families in a dairy farm in Shanghai using polymerase chain reaction–single strand conformation polymorphism (PCR–SSCP) technique, and milk yield, milk fat percentage, milk protein percentage, 305 day corrected milk yield, 305 day milk fat yield, 305 day milk protein yield and somatic cell score (SCS) were measured and analyzed, and the mRNA levels of IL8 genotypes in blood were detected by real-time PCR. The results showed that three genotypes, KK, KA and AA were detected with frequencies of 0.187, 0.451, and 0.362, respectively. The gene frequencies of K and A were 0.412 and 0.588, respectively. The significant association of the IL8 mutations with milk yield, 305 day milk protein yield, 305 day corrected milk yield and 305 day milk fat yield, SCS, and significant association with milk protein percentage were identified, while their association with milk fat percentage were not significant. KK had higher milk yield, 305 day milk protein yield, 305 day corrected milk yield and 305 day milk fat yield than AA or KA, and the least square mean of SCS of KK was significantly lower than that of AA or KA. AA had significant lower milk protein yield than KK or KA. The relative IL8 mRNA level of KK in blood was the highest. These findings demonstrated that IL8 genotype significantly correlated with mastitis resistance and the locus could be a useful genetic marker for mastitis resistance selection and breeding in Chinese Holstein.

This experiment was conducted to analyze the association between polymorphism of SCD1 gene and milking traits for Chinese Holstein.The polymorphism of the A293V site in SCD1 gene was investigated for 610 Chinese Holstein cows from a dairy farm in Shanghai using polymerase chain reaction-single strand conformation polymorphism(PCR-SSCP) technique,and using general linear model,the effects of the polymorphism of the A293V site on daily milk yield,fat percentage,milk protein percentage,305 days corrected milk yield,milk fat yield,milk protein yield and SCS were analyzed.Three genotypes were found and the genotypic frequencies of AA,AV and VV were 0.634,0.323 and 0.043,respectively.The allele frequencies of A and V were 0.796 and 0.204.A significant association between SCD1 A293V and both fat and protein percentages was identified(P0.05),no significant association between SCD1 A293V and tested-day milk yield,SCS,305-day corrected milk yield,305-day protein yield and 305-day fat yield(P0.05) was found.LSD showed that the cow with VV genotype had higher milk fat percentage and protein percentage than those with AV and AA genotypes(P0.01).The SCD1 A293V substitution has some genetic effect on milking traits,and its mechanism need to be further researched.

【Objective】Using Gas Chromatography to determine milk fatty acids and analyze the effect of season,milking period,parity and mastitis on milk fatty acids.【Method】147 Chinese Holsteins were used in the experimental farm of Yangzhou University as research objects and the process was analyzed by general linear model.【Results】The results showed that the fatty acids of raw milk in winter had the highest quality.With the increasing of lactation and parities,the fatty acid content decreased,but the proportion was gradually optimized.Mastitis reduced the fatty acid content,but it had little effect on the proportion of fatty acids.【Conclusion】In the production practice,each factors affecting fatty acid composition of raw milk should be flexibly regulated,so as to improve the milk quality.

【Objective】 Multifactor Dimensionality Reduction(MDR) model was used to identify the interaction of CXCR1 and IL-8 and their impacts on the risk of mastitis susceptibility of Chinese Holstein,and to test it's feasibility in analyzing genes-genes interactions.【Method】 The polymorphisms of 7 SNP sites including the 5′ flanking region and coding region of CXCR1 and exon 4 and exon 5 of IL-8 were detected by PCR-SSCP and direct sequencing for 634 Chinese Holstein,including 228 individual mastitis cow,from Jinshan Breeding Dairy Farm of Bright Dairy Group of Shanghai,and to identify the interaction of CXCR1 and IL-8 and their impacts on the risk of mastitis susceptibility using MDR and Logistic regression.【Result】Four SNPs were found for CXCR1 including three SNPs(-1 830(A/G),-1 768(T/A),-344(T/C)) in 5′ flanking region and 783(C/A) in coding region.A linked mutation in 2 789(A/G) and 2 862(T/C) sites was found for IL-8 gene,and this mutation results in the transaction of AA from Ser to Gly,and Cys to Arg.The main effects of polymorphism of 5 SNPs of CXCR1 and IL-8 gene showed no significant impacts on the mastitis susceptibility of cow based on the single factor Logistic regression.The interactions of CXCR1-(-1 768)-IL-8,CXCR1-(-1 768)-(783)-IL-8,and CXCR1-(-1 768)-(-344)-(783)-IL-8 showed significant impacts on the mastitis susceptibility of cow using MDR model,and the cross-validation consistency was maximum(10/10).The interactions of CXCR1-(-1 768)-IL-8 and CXCR1-(-1 768)-(783)-IL-8 showed high testing balance accuracy(0.5457 and 0.5485,respectively).The interaction of CXCR1-(-1 768)-IL-8 was high degree synergy for mastitis susceptibility from the interaction dendrogram of multi-genotypes of CXCR1 and IL-8.In the meanwhile,the interactions of CXCR1-(-1 768)-IL-8 showed significant impacts on the mastitis susceptibility of cow using Logistic regression model including the main effect of 5 SNPs and the interaction effect of CXCR1-(-1 768)-IL-8 and CXCR1-(-1 768)-(783)-IL-8(P<0.05).【Conclusion】The interactions of CXCR1-(-1 768)-IL-8 was the best multi-genotype model to estimate the risk of mastitis susceptibility of Chinese Holstein.MDR and Logistic regression can also be used to estimate the risk of mastitis susceptibility of Chinese Holstein.MDR appeares better ability than Logistic regression for detection of high-order interactions,and MDR and Logistic regression have advantages and disadvantages when compared to each other.Combined use of MDR and Logistic regression may be preferable when dealing with interaction analysis.