大白猪不同近交程度对繁殖性能的影响

对4 749头近交系数在0～20％范围内的大白猪繁殖性能的统计分析结果表明,不同近交程度组间平均产仔数无显著差异(P＞0.05),相同胎次不同近交程度组间产仔数差异不显著(P＞0.05),但不同胎次间产仔数差异显著(P＜0.05);说明母猪近交程度在0～20％之间对产仔数的影响不大,主要与母猪分娩胎次关系较为密切.不同近交系数组间平均产活仔数以10.1％～20％组最低,但各组之间差异不显著(P＞0.05),相同近交程度组内头胎与经产间差异显著,趋势基本和产仔数相同.不同近交系数对平均产死仔数的影响差异显著(P＜0.05),以10.1％～20％组最高;各组内胎次间(头胎和经产组)产死仔数也以10.1％ ～ 20％组最高,与其它组差异显著(P＜0.05),说明近交繁殖会影响胚胎的发育,造成产死仔数的增加.     

不同近交程度对大白猪生长性能的影响

遗传学上将有亲缘关系的个体间的交配称为近交,但在育种学上认为,如果双方间存在亲缘关系就叫近亲交配,简称近交。本文使用stata软件通过单因素方差分析研究了不同近交程度对大白猪背膘厚的表型值、EBV值和大白猪达100 kg体重的日龄的表型值、EBV值的影响。试验结果表明:近交系数低于12.5%时对背膘厚度和达100 kg日龄的表型值、EBV值的影响均不显著(P》0.05);近交系数高于1 2.5鬈时仅对达100 kg日龄EBV值的影响有极显著差异(P≤0.01),对其他三个性状影响均不显著(P>0.05)。可见,温和近交(近交系数<12.5%)对大白品种的猪背膘厚和达100 kg体重日龄的影响不显著。     

ESR基因多态性对不同胎次的大白猪母猪产活仔数的影响

为了研究ESR基因对大白猪经产母猪整个生产周期的影响并应用于猪繁殖性状改良,试验检测了该基因在472头大白猪经产母猪中的多态性分布,并根据基因分型结果分析了不同基因型对该群体1774胎产活仔数的影响.结果表明,AA、AB、BB基因型频率为0.206、0.572、0.222,AB基因型为优势基因型;A、B基因频率为0.493、0.507,B等位基因为优势等位基因.通过对不同胎次的分析发现,头胎AB基因型个体的产活仔数高于AA、BB基因型个体;2胎BB基因型个体的产活仔数高于AA、AB基因型个体;3胎AB、BB基因型个体的产活仔数高于AA基因型个体;4～7胎AA基因型个体的产活仔数最多(5胎除外),8胎及以上胎次AB基因型个体的产活仔数最多,呈现一定的规律性,但是各胎次内的差异均不显著.     

大白猪高繁母本新品系系谱结构及近交程度分析

本文通过整理各世代的系谱资料,系统分析了大白猪高繁母本新品系近交程度和世代组成的遗传结构。结果表明:大白猪高繁母本新品系的平均近交系数为1.23%,仍处于较低水平,近交系数年增量为0.239 1%,群体有效含量为209.12头。     

不同类群大白猪窝产仔数的遗传分析

对双肌臀大白猪和普通大白猪组成的 561窝产仔数的资料进行了遗传分析。结果表明 :公猪和胎次均对母猪产仔数 (总产仔数和活产仔数 )具有极显著影响 (P <0 .0 0 1 ) ,季节和类群均对母猪产仔数 (总产仔数和活产仔数 )具有显著影响 (P <0 .0 5)。大白猪产仔数的平均值随胎次增长而增加。夏季分娩的大白猪具有最高的产仔数 ,依次为春季和冬季 ,秋季最低。大白猪总产仔数和活产仔数的遗传力分别为0 .0 9和 0 .1 0 ,属低遗传力 ,直接选择窝产仔数几乎没有效果 ;它们之间的遗传相关为 0 .80 ,表型相关为0 .85,环境相关为 0 .90 ,它们之间的协遗传力为 0 .0 8。这些参数表明总产仔数和活产仔数是两个不同的性状 ,在生产实践中单独记录它们是有理由的、必要的。     

ESR基因多态性对不同胎次的大白猪母猪产活仔数的影响

为了研究ESR基因对大白猪经产母猪整个生产周期的影响并应用于猪繁殖性状改良,试验检测了该基因在472头大白猪经产母猪中的多态性分布,并根据基因分型结果分析了不同基因型对该群体1774胎产活仔数的影响。结果表明,AA、AB、BB基因型频率为0.206、0.572、0.222,AB基因型为优势基因型;A、B基因频率为0.493、0.507,B等位基因为优势等位基因。通过对不同胎次的分析发现,头胎AB基因型个体的产活仔数高于AA、BB基因型个体;2胎BB基因型个体的产活仔数高于AA、AB基因型个体;3胎AB、BB基因型个体的产活仔数高于AA基因型个体;4～7胎AA基因型个体的产活仔数最多（5胎除外）,8胎及以上胎次AB基因型个体的产活仔数最多,呈现一定的规律性,但是各胎次内的差异均不显著。     

长白、大白猪纯繁与杂交效果比较试验

湖北省荆州市丫角种猪场于2002年9月从国内原种场引进丹麦长白、大白种猪扩繁。现从繁殖数据库中选择2004、2005年763头分娩母猪的繁殖记录,分为长白(L)、大白(Y)纯繁(LL、YY)及杂交(LY、YL)4个组合,各组头数分别为75、97、287、304头,对繁殖性状(窝均产仔数、窝均产活仔数、窝均断奶活仔数)进行比较分析。结果表明,LY、YL杂交组窝均产仔数的杂种优势率分别为1.60%、7.41%;窝均产活仔数的杂种优势率分别为3.31%、5.43%;窝均断奶活仔数的杂种优势率分别为3.19%、5.13%。YL组较LY组窝均产仔数提高5.72%;窝均产活仔数提高2.05%;窝均断奶活仔数提高1.88%。杂种优势率(H%)=[LY(或YL)-(L Y)/2]/[(L Y)/2]×100%(式中L、Y分别代表长白、大白某性状平均表现值,LY代表长白×大白的平均表现值,YL则相反),详见表1。     

大白猪繁殖性状全基因组关联分析

本研究利用全基因组关联分析（GWAS）挖掘与大白猪总产仔数（TNB）、产活仔数（NBA）和健仔数（NHP）相关的候选基因。选择1 100头大白猪为实验材料,通过提取耳尾组织样DNA并利用“中芯一号”芯片进行基因型分型,采用PLINK v1.9对获得的基因型数据进行质控后用于GWAS研究。rMVP软件对每个SNP与性状做关联分析,确定出显著位点。结果表明：对于TNB性状共有3个SNPs呈基因组水平或染色体水平显著;NBA性状共有4个SNPs呈基因组水平或染色体水平显著;NHP分析得到18个SNPs呈基因组水平或染色体水平显著。在上述显著SNPs附近共有23个候选基因,根据基因功能注释推测ESR1、ZP3、YWHAG、HSPB1、MDH2、PCCB是能够影响繁殖性状的重要候选基因。     

FSHβ基因的多态性分布及其对大白猪产活仔数的影响

为了研究猪繁殖性状候选主效基因FSHβ在大白猪不同胎次中的遗传效应,并应用于大白猪繁殖性状的遗传改良,采用PCR方法检测了该基因在2个大白猪育种群共802头母猪中的多态性分布,并分析了其对产活仔数的影响,其中湖北天种公司大白猪群体样本数为472头,分析统计胎次1774胎,等位基因A的频率为0.447、等位基因B的频率为0.553;宜昌正大公司大白猪群为330头,分析统计胎次1644胎,等位基因A、B的频率分别为0.312、0.688。分析该位点的多态性与产活仔数的关系,结果发现,头胎不同基因型对产活仔数的影响为ABBBAA,二胎为AAABBB,经产胎次和所有胎次均为ABAABB,但差异均不显著。综合分析结果表明,A等位基因对大白猪产活仔数的影响要优于B等位基因,AB基因型母猪的产活仔数要优于其他2种基因型,提高生产猪群该基因的杂合子个体数比例有望取得更大的经济效益。     

大白猪产仔数相关基因多态性及其遗传效应

为比较繁殖性状主效基因对不同品系大白猪产仔性能的影响,以便在不同品系大白猪选种实际应用提供依据,本试验采用PCR-RFLP技术,分别对促卵泡素亚基β(FSHβ)、催乳素受体(PRLR)、视黄醛结合蛋白(RBP4)、核受体辅激活蛋白Ⅰ(NCOA1)、瘦素(LEP)等5种与繁殖性状相关候选基因的基因型频率以及不同基因型的总产仔数和产活仔数在英系、美系大白猪群体中进行了检测与关联分析。结果显示:NCOA1和LEP基因多态位点分别在英系和美系大白猪中未检测到BB基因型,其他基因多态位点均存在AA、AB、BB等3种基因型,在美系大白猪群体中5个基因多态位点均符合Hardy-Weinberg平衡定律(P>0.05);而在英系大白猪群体中除在FSHβ、NCOA1、LEP基因多态位点均处于Hardy-Weinberg平衡状态(P>0.05)外,在PRLR、RBP4基因多态位点处于Hardy-Weinberg不平衡状态(P<0.01)。各基因不同基因型与产仔性状关联分析结果表明,无论是英系大白猪还是美系大白猪,FSHβ基因多态位点在窝总产仔数和产活仔数中均表现为BB型为有利基因型,在美系大白猪中BB型较AA型总产仔数高1.6961头(P<0.05),产活仔数高1.696 9头(P<0.05),但在英系大白猪中不存在显著差异(P>0.05);LEP基因在英系大白猪中BB型为有利基因型,分别较AA型母猪总产仔数高0.790 7头、产活仔数高1.409 3头(P<0.05),而在美系大白猪中不存在显著差异(P>0.05);PRLR、RBP4、NCOA1基因对产仔数不存在显著差异(P>0.05)。     

大白猪哺乳期背膘损失对繁殖性能的影响

为了研究大白母猪哺乳期背膘损失对其繁殖性能的影响,试验选取大白母猪1 178头,统计6个胎次的总产仔数、产活仔数、健仔数、断奶窝重、断奶发情间隔、哺乳期背膘损失等性状,根据哺乳期的背膘损失情况将母猪分为6组：<0、0~1、1~2、3~4、5~6、>6 mm,以断奶窝重为协变量,利用最小二乘检验开展组间总产仔数、产活仔数、健仔数、断奶发情间隔等性状的差异显著性分析。结果显示,大白母猪6个胎次平均总产仔数、产活仔数、健仔数、断奶窝重、断奶发情间隔和哺乳期背膘损失分别为13.67头、11.51头、10.32头、65.90 kg、4.83 d和2.89 mm,大白母猪1~6胎产仔数在各组间存在显著差异（P<0.05）。综合全部6个胎次的结果可知,第4、5、6组间差异不显著（P>0.05）,但均显著高于第1、2、3组（P<0.05）;第4组总产仔数最高,达13.54头,比第1、2、3组分别高出1.90、2.29和1.63头（P<0.05）。虽然各胎次中各组间产活仔数和健仔数性状有时也出现显著差异,但综合分析6个胎次组间并未出现显著差异（P>0.05）。从断奶发情间隔性状来看,各组间均未出现显著差异（P>0.05）。结果表明,在大白猪生产中,将哺乳期母猪的背膘损失控制在3~4 mm可以获得更高的总产仔数。     

Estimation of inbreeding depression on female fertility in the Finnish Ayrshire population

Single nucleotide polymorphism (SNP) data enable the estimation of inbreeding at the genome level. In this study, we estimated inbreeding levels for 19,075 Finnish Ayrshire cows genotyped with a low‐density SNP panel (8K). The genotypes were imputed to 50K density, and after quality control, 39,144 SNPs remained for the analysis. Inbreeding coefficients were estimated for each animal based on the percentage of homozygous SNPs (F_PH), runs of homozygosity (F_ROH) and pedigree (F_PED). Phenotypic records were available for 13,712 animals including non‐return rate (NRR), number of inseminations (AIS) and interval from first to last insemination (IFL) for heifers and up to three parities for cows, as well as interval from calving to first insemination (ICF) for cows. Average F_PED was 0.02, F_ROH 0.06 and F_PH 0.63. A correlation of 0.71 was found between F_PED and F_ROH, 0.66 between F_PED and F_PH and 0.94 between F_ROH and F_PH. Pedigree‐based inbreeding coefficients did not show inbreeding depression in any of the traits. However, when F_ROH or F_PH was used as a covariate, significant inbreeding depression was observed; a 10% increase in F_ROH was associated with 5 days longer IFL0 and IFL1, 2 weeks longer IFL3 and 3 days longer ICF2 compared to non‐inbred cows.     

Estimation of litter size variability phenotypes in Large White sows

The objective of this study was to obtain new phenotypes of phenotypic variability for the total number born (TNB) in pigs using the residual variance of TNB. The analysis was based on 246,799 Large White litter observations provided by Topigs Norsvin. Three animal models were used to obtain estimates of residual variance for TNB: the basic model (BM) containing fixed effects of farm–year and season and random effects of animal and permanent environmental sow, the basic model with an additional fixed effect of parity (BMP) and a random regression model (RRM). The within-individual variance of the residuals was calculated and log-transformed to obtain three new variability traits: LnVarBM, LnVarBMP and LnVarRRM. Then, (co)variance components, heritability, the genetic coefficient of variation at the standard deviation level (GCV_SDe) and genetic correlations between the three LnVar's and between the LnVar's and mean total number born (mTNB) were estimated with uni-, bi- and trivariate models. Results indicated that genetically LnVar's are the same trait and are positively correlated with the mTNB (~0.60). Thus, both traits should be included in breeding programmes to avoid an increase in TNB variability while selecting for increased TNB. Heritability of the LnVar's was estimated at 0.021. The GCV_SDe for LnVar's showed that a change of 8% in residual standard deviation of TNB could be obtained per generation. Those results indicate that phenotypic variability of litter size is under genetic control, thus it may be improved by selection.     

大白猪胎盘效率遗传规律的初步研究

本文分析了 77头纯种大白母猪的 469头初生仔猪的胎盘效率、胎盘面积、胎盘长度、胎盘重及初生重等性状资料 ,估计了各性状间的简单相关系数 ,应用非求导约束最大似然法 (MTDFREML)估计大白猪胎盘效率、胎盘面积、胎盘长度、胎盘重及初生重的遗传力 ,估计结果分别为0 46 ,0 2 5 ,0 1 1 ,0 1 4和 0 2 9     

Effect of candidate gene polymorphisms on reproductive traits in a Large White pig population

The objective of this study was to test for association of candidate single nucleotide polymorphisms (SNPs) with sow prolificacy reproductive traits, such as litter size, ovulation rate and lifetime performance, in gilts of a Large White pig population. Preliminary research on 25 animals selected from the high‐ and low‐performance groups of 347 animals with case‐control studies indicated that seven genes were associated with total number of piglets born (TNB). Six of the seven genes were associated with reproductive traits, including TNB, number of piglets born alive (NBA) and average weight of piglet weaning (AWW). A MBL2 SNP was significantly associated with TNB and NBA in first parity. A CFB SNP was associated with TNB in first parity. An ACE SNP was associated with TNB in first and second parities. An EGF polymorphism was associated with TNB, NBA and AWW in second parity. A KCNC2 polymorphism was significantly associated with TNB and NBA in second parity. A SLC22A5 SNP was associated with TNB and NBA in second parity. Six candidate SNPs were associated with TNB; the only exception was a PRKAG3 polymorphism. A candidate gene approach enables some of these polymorphisms to be used in genetic improvement programs based on marker‐assisted selection.     

大白猪TLR4基因外显子1遗传变异及其与细胞因子水平的关系

本实验运用PCR-SSCP技术对大白猪TLR4基因外显子1遗传变异进行分析,同时利用ELISA方法对外周血重要细胞因子(IL-2、IL-4、IL-6、IFN-Beta、IL-10、IL-12)的水平进行测定,旨在分析大白猪TLR4基因外显子1多态性及其与重要细胞因子水平间的关系,探讨将其作为抗F18大肠杆菌病遗传标记的可行性。结果表明:大白猪TLR4基因外显子1存在G93C同义突变位点,共检测到3种基因型,分别定义为BB、BC和CC;关联分析结果表明,大白猪TLR4外显子1变异位点对机体重要细胞因子水平没有显著影响(P>0.05),表明基于该位点的分子选育不会对机体免疫应答和一般抗病力产生不利影响。结果提示,有必要将TLR4基因外显子1的变异位点作为抗大肠杆菌病的重要遗传标记进行深入研究。     

长白和大白猪主要生长性状的遗传参数估计

旨在分析母猪的出生年份、出生季节、初生重、开测日龄等固定效应对长白、大白猪主要生长性状的影响,并对目标生长性状进行遗传参数估计(遗传力、遗传方差、表型相关和遗传相关),为猪的遗传改良提供基本依据.本试验利用GLM模型分析试验猪群(398头长白猪和1176头大白猪)的固定效应对猪生长性状的影响,并采用多性状动物模型对目标...     

Assessing effective population size,coancestry and inbreeding effects on litter size using the pedigree and SNP data in closed lines of the Iberian pig breed

The complete pedigree of two closed Iberian pig lines (Gamito and Torbiscal), with 798 and 4077 reproducers, has been used to measure the evolution of coancestry (f) and inbreeding (F) for autosomal and X‐linked genes along 16 and 28 respective equivalent discrete generations. At the last generation, the mean values of each line were f = 0.41 and 0.22, F = 0.35 and 0.18, f_X = 0.46 and 0.22 and F_X = 0.47 and 0.19, respectively. Other calculated parameters were the effective number of founders (final values, 6.8 and 35.2) and non‐founders (1.5 and 2.4), founder genome equivalents (1.2 and 2.3) and effective population size (16.0 and 57.7). Measures of Torbiscal effective size based on rates of coancestry (66.1), inbreeding (65.0) and linkage disequilibrium (71.0) were estimated from whole‐genome SNP genotyping data. Values of new and old inbreeding and their respective rates by generation were computed to detect purging effects of natural selection. The analysis of 6854 Torbiscal litters showed significant negative impacts of new and fast inbreeding on litter size, as expected from the purging hypothesis: ?0.20 born piglets per litter by a 10% of new inbreeding, and ?0.03 and ?0.02 piglets by 1% of total and new inbreeding rates, respectively. The analysis performed on 1274 litters of the Gamito line failed to show purging effects. The only significant results were reductions in ?0.91 and ?0.17 piglets by a 10% of old and X‐linked genes inbreeding, respectively. These results may be useful for some practical issues in conservation programs of farm or captive wild animals.     

大白猪PTGS2基因外显子2多态性及其与繁殖性状的关联分析

试验旨在研究前列腺素内过氧化物合酶2（prostaglandin-endoperoxide synthase 2,PTGS2）基因的单核苷酸多态性,并将其与大白猪的繁殖性状进行关联分析,为猪分子遗传标记提供依据。以美系及法系纯种大白猪基因组DNA为模板,构建DNA混合池,通过克隆测序比对,检测猪PTGS2基因的遗传变异;采用PCR-RFLP技术对多态性位点进行基因分型,并与目标性状进行关联分析。结果显示,在猪PTGS2基因外显子2上存在1个g.86A>G碱基突变,并具有Msp Ⅰ酶切位点多态性,且在大白猪群体中检测到AA、AG和GG 3种基因型;哈迪-温伯格平衡检验结果显示,在法系大白猪群体中,PTGS2基因g.86A>G多态性分布达到遗传平衡状态（P>0.05）。关联分析结果表明,在美系大白猪群体中,AA基因型初产母猪弱仔数显著少于AG基因型（P<0.05）,AA基因型经产母猪初生窝重显著高于AG基因型（P<0.05）;在法系大白猪群体中,GG基因型个体总产仔数、健仔数和初生窝重均高于AA和AG基因型,但未达到显著水平（P>0.05）。PTGS2基因外显子2 g.86A>G多态性位点显著影响初生窝重和弱仔数,可作为猪分子标记辅助选择育种的潜在位点。