安徽省猪育种核心群场间联系性和遗传参数估计

本研究旨在分析安徽省3家(分别标记为1、2、3)国家生猪核心育种场大白猪、长白猪和杜洛克猪的场间遗传联系和主要性状的遗传参数,为目标群体的遗传评估奠定基础。利用DMU软件和动物模型计算了场间关联率,并估计了不同群体总产仔数(TNB)、产活仔数(NBA)、初生窝重(LBW)、达100 kg体重日龄(AGE)和100 kg体重背膘厚(BF)的加性遗传、永久环境和窝效应方差。其中繁殖性状共计24 933条,生长性状共计44 034条。结果表明:1场与其他场间没有关联,2场和3场的大白猪、长白猪和杜洛克猪场间关联率分别为3.4%、25.6%和13.8%。根据场间关联率把3个场分为2个群体(1场和2+3场),其中1场不同品种TNB遗传力估计值变化范围为0.03~0.09,NBA为0.05~0.07,LBW为0.07~0.10,AGE为0.54~0.56,BF为0.26~0.35;2+3场不同品种TNB遗传力估计值变化范围为0.05~0.07,NBA为0.05~0.06,LBW为0.02~0.09,AGE为0.58~0.59,BF为0.40~0.43。1场和2+3场永久环境效应范围分别0.03~0.10和0.13~0.12,窝效应均值分别为0.07和0.00。其中各繁殖性状的遗传力估计值偏低,但均在文献推荐范围之内,可望用于目标群体的遗传评估。     

杜洛克母猪繁殖性状遗传参数估计

本研究旨在分析某杜洛克群体包括总产仔数（TNB）、产活仔数（NBA）、健仔数（NHB）、弱仔数（NWB） 4个繁殖性状的遗传参数。利用R软件对影响杜洛克猪繁殖性状的固定效应进行方差分析，并利用DMU软件计算了繁殖性状的遗传参数。结果显示：TNB、NBA、NHB和NWB的遗传力分别为0.082±0.0085、0.075±0.0082、0.066±0.0075和0.029±0.0075；此外，TNB与NBA、NHB和NWB的遗传相关变化范围是0.32～0.93。可见，在该群体中上述繁殖性状均为低遗传力性状，且遗传趋势分析表明，该杜洛克群体的母猪繁殖性状可能未经过系统的遗传改良，现有遗传进展可能与杜洛克猪生长性状的协同选择相关。本研究旨在为杜洛克猪的繁殖效率改良提供参考，为终端父本本土化贡献力量。     

长白、大白猪窝性状遗传参数估计

本研究旨在估计北京、天津地区长白猪、大白猪窝性状的遗传参数，为该群体进一步制定合理的育种计划和方案提供依据。收集种猪场2016—2021年3 906头长白母猪的11 583窝数据和22 070头大白母猪的62 210窝数据，利用R v4.2.2软件对影响窝性状的固定效应进行显著性检验，运用DMU 6.0软件对长白猪、大白猪的总产仔数（Total Number Born,TNB）、产活仔数（Number Born Alive,NBA）、初生窝重（Litter Birth Weight,LBW）、平均个体初生重（AverageBirth Weight,ABW）、仔猪均匀度（PigletUniformity,PU）进行遗传参数估计，采用单性状重复力模型估计各性状的方差组分，采用双性状动物模型估计性状之间的遗传相关，并分析分娩胎次对各性状的影响。结果显示：分娩场次、年份、胎次对窝性状影响显著（P<0.001），长白猪的TNB、NBA、LBW、ABW、PU遗传力分别为0.095±0.015、0.090±0.014、0.106±0.017、0.192±0.021、0.023±0.014，大白...     

大白猪、长白猪繁殖性状的遗传参数估计

<正>养猪生产中,随着胴体瘦肉率逐渐达到最佳水平,母猪繁殖性能的改良对追求利益最大化更加重要。而准确的估计繁殖性状遗传参数,对估计育种值、预测遗传进展及优化育种方案是必不可少的~([1])。本文根据全国生猪遗传改良计划遗传评估的方法,对天津市某两家国家核心育种场主要品种大白猪、长白猪的繁殖性状总产仔数(TNB)、产活仔数(NBA)、初生窝重(LBW)的遗传参数进行估计,包括各性状的方差组分、遗传力和遗传相关的分析。目的是奠定目     

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1 176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性状进行遗传参数估计。目标生长性状包括达100 kg体重日龄（age to 100 kg,AGE）、达100 kg背膘厚（backfat to 100 kg,BF）、100 kg平均日增重（average daily gain to 100 kg,ADG）。研究表明,在大白和长白猪中,猪的出生年、出生季、初生重以及开测日龄对生长性状均具有极显著的影响（P<0.001）;长白猪的AGE、ADG和BF的遗传力分别为0.321、0.327和0.324,大白猪对应性状的遗传力分别为0.454、0.469和0.408;长白猪的ADG和AGE之间的遗传相关、表型相关分别为-0.990、-0.995,大白猪的ADG和AGE之间的遗传相关、表型相关分别为-0.993、-0.998,均呈现较强的负相关。长白、大白猪的生长性状（AGE、ADG、BF）均属于中等遗传力性状,其出生年份、出生季节、初生重和开测日龄对猪的生长性状影响较大。在遗传参数估计分析时,提高样本数量并提升表型数据质量,可以增加遗传参数估计的可靠性。本研究中的生长性状遗传参数估计结果较为可靠,可为后续的遗传改良提供参考。     

湖北白猪优质系主要繁殖性状的遗传参数估测

应用多性状动物模型DFREML方法估计湖北白猪优质系主要繁殖性状的遗传参数。结果表明,产仔数（TNB）、产活仔数（ANB）、初生窝重（LWB）和21日龄窝重（LW21）的遗传力估计值分别为0.16、0.19、0.22和0.09。各性状间（TNB/ANB、TNB/LWB、TNB/LW21、ANB/LWB、ANB/LW21、LWB/LW21）的遗传相关分别为0.89、0.72、0.61、0.59、0.43和0.54。     

我国杜洛克、长白、大白猪区域性联合遗传评估研究

旨在根据我国杜洛克、长白和大白猪3个品种的场间遗传联系情况进行区域性跨场联合遗传评估,为全国联合遗传评估奠定基础。本研究利用杜洛克、长白和大白3个猪种分别在9个遗传关联组共39家国家生猪核心育种场2011-2016年的生长性状数据126 070条、187 975条和491 350条,繁殖性状数据36 542、78 409条、195 031条。生长性状包括达100 kg体重日龄(age to 100 kg,AGE)、100 kg活体背膘厚(backfat to 100 kg,BF),繁殖性状为总产仔数(total number born,TNB)。遗传参数和育种值分别采用约束极大似然方法(restricted maximum likelihood,REML)和最佳线性无偏预测法(best linear unbiased prediction,BLUP)进行估计。结果表明,区域性联合遗传评估的遗传力比单场评估更准确,同样,跨场联合评估育种值估计的准确性要高于单场遗传评估。杜洛克、长白、大白猪AGE联合评估的平均准确性比单场评估分别提高了20. 9%、11. 9%、17. 3%; BF联合评估的平均准确性比单场评估分别提高了21. 3%、16. 3%、21. 0%; TNB联合评估的平均准确性比单场评估分别提高了31. 2%、14. 4%、6. 6%。联合评估后群体规模变大,遗传变异增大,个体育种值估计准确性提高,有助于联合育种。因此,我国开展杜洛克、长白和大白猪3个品种的区域性联合遗传评估是可行的。     

中国大白猪S_(II)系繁殖性状的遗传参数估测

应用多性状动物模型DFREML方法估计了中国大白猪SII系繁殖性状的遗传参数。结果表明:总产仔数(TNB)、活产仔数(ANB)、初生窝重(LWB)、20日龄窝重(LW20)的遗传力估计值分别为0.06、0.10、0.07和0.15。20日龄窝重(LW20)的母体效应为0.20,而其它性状的母体效应均较低。各性状TNB/ANB、TNB/LWB、TNB/LW20、ANB/LWB、ANB/LW20、LWB/LW20的遗传相关分别为0.94、0.81、0.74、0.88、0.71和0.53。     

上海市闵行区畜禽种场大白猪繁殖性能分析

繁殖性能对于养猪而言,因其直接关乎生产成本,进而影响经济效益,所以意义重大。但这类性状的遗传力很低,例如产仔数的遗传力只有0~0.16,因此需研究影响繁殖性能的因素并结合运用现代BLUP育种技术和先进的人工授精技术,以提高母猪的繁殖性能。本文以上海闵行区畜禽种场大白猪为研究对象,对其繁殖性能的影响因素进行分析。通过分析可知,年季和胎次对总产仔数、产活仔数、初生窝重、校正21日龄窝重的影响均达到极显著水平(P0.01);胎次对TNB、NBA、LBW的作用规律是一致的,头胎的TNB、NBA、LBW较低,第3、4胎达到最大,7胎以后繁殖性能呈明显的下降趋势。     

湘村黑猪繁殖性能的遗传效应分析

依据调查记录的育种数据资料,运用多性状非求导约束最大似然法(multiple traits derivative free restricted maximum likelihood,MTDFREML)数学模型,对湘村黑猪繁殖性状进行了遗传参数估计。结果表明,窝总产仔数(TNB)、产活仔数(NBA)、初生窝重(LW)和21日龄窝重(LW21)的遗传力分别是0.18、0.15、0.07、0.09。母体效应率、窝效应率的变化范围分别是0.07~0.11、0.14~0.33;性状间遗传相关、永久环境相关、残差相关、表型相关范围分别为0.40~0.91、0.68~0.97、0.33~0.62、0.31~0.87。     

Genetic parameters for litter traits at different parities in purebred Landrace and Yorkshire pigs

Comparison of the multi‐trait animal model and the traditional repeatability model was carried out using data obtained from 6,424 Landrace and 20,835 Yorkshire sows farrowed from January 2000 to April 2018 in order to estimate genetic parameters for litter traits at different parities. Specifically, records of the total number born (TNB), number born alive (NBA), total number of mortality (MORT), number of stillborn (NSB) and number of mummified pigs (MUM) were used. Although results showed the heterogeneity of heritability for litter traits at different parities, the mean heritability estimates from the multi‐trait model were found to be higher than those of the repeatability model for all traits in both pig breeds. In terms of genetic correlation between parities, a slight difference in genetic control in the first parity was noted for TNB and NBA in Landrace and Yorkshire pigs. The correlation between the first parity and later parities ranged from 0.48 to 0.74 for TNB and NBA in both breeds. Moreover, genetic correlation between parities for MORT and NSB was observed to be high for parities higher than 2 in Yorkshire pigs. For MUM, genetic correlation between the first and other parities was generally low in both breeds, indicating that culling pigs on the basis of MUM at the first parity could probably be unreasonable. Overall, the results of this study suggest that the multi‐trait approach for litter size traits is useful for the accurate estimation of genetic parameters.     

Genetic Parameter Estimation and Affecting Factor Analysis of Reproduction Traits in Large White Sow

In this study,7 945 litter records from 2 904 Large White sows were used to determine the effect of parity,mating season and the classified gestation length on total number born (TNB),number born alive (NBA),number healthy birth (NHB),number weak birth (NWB),deform fetus,number born dead (NBD),mummy fetus and stillbirth. Genetic parameters and genetic correlation of the above reproduction traits were estimated by restricted maximum likelihood (REML) procedure.The results indicated that the parity had non-significant effect on deform fetus (P=0.2619) and mummy fetus (P=0.4639),but had significant effect on other 7 reproduction traits (P <0.01).The effect of mating season on gestation length,NBA,NWB,mummy fetus,NBD and NHB were highly significant (P <0.01),while mating season effect on deform fetus was not significant (P=0.3993).Moreover,the effect of mating season on TNB and stillbirth were significant (P <0.05).Effect of different gestation length classification was significant on mummy fetus (P <0.05),and was highly significant on the other 7 traits (P <0.01).The gestation length got the highest heritability,at 0.34,while others below 0.2 as low heritability traits.There was a negative genetic correlation (r_g=-0.10) between gestation length and TNB,while a strong positive genetic correlation exists among TNB,NBA and NHB (r_g >0.80).The genetic correlation between gestation length and other reproductive traits was low,the highest one appears between gestation length and deform fetus reached -0.17.We concluded that the gestation length was medium heritability trait,it was influenced not only by environment factors (such as parity,mating season) but also reproductive traits like TNB,and gestation length could be used as an indirect indicator in pig production.     

大白猪繁殖性状遗传参数估计及影响因素的效应分析

本研究对7 945窝大白母猪妊娠周期、总产仔数、产活仔数、健仔数、弱仔数、畸形数、死仔数、木乃伊及死胎数9个繁殖性状进行了最小二乘分析,分析了胎次、配种季节及妊娠周期分类对母猪繁殖性能的影响;并利用动物模型REML(约束最大似然)方法估计动物繁殖性状的遗传力及性状之间的遗传相关.结果表明,胎次对畸形数(P=0.2619)和木乃伊(P=0.4639)影响不显著(P >0.05),对其他7个繁殖性状影响极显著(P <0.01);配种季节对妊娠周期、产活仔数、弱仔数、木乃伊、死仔数及健仔数影响极显著(P <0.01),对畸形数(P=0.3993)影响不显著(P> 0.05),对总产仔数和死胎数影响显著(P <0.05).妊娠周期对木乃伊影响显著(P <0.05),对其他7个性状影响极显著(P <0.01).妊娠周期遗传力最高,为0.34,其他繁殖性状遗传力都低于0.2,为低遗传力性状.总产仔数与妊娠周期之间存在负遗传相关(r_g=-0.10),与产活仔数及健仔数之间存在较强的正遗传相关,遗传相关都超过0.80.妊娠周期与其他繁殖性状之间的遗传相关较小,最高的为妊娠周期与畸形数之间的遗传相关为-0.17.由此得出结论,妊娠周期属于中等遗传力性状,妊娠周期不仅受到胎次、季节等环境因素的影响,而且也受总产仔数等繁殖性状的影响,妊娠周期可作为养猪生产的间接指标.     

应用动物模型REML法估计金华猪繁殖性状遗传参数

试验资料取自金华猪场 1 979～1 999年金华猪繁殖性能的生产记录。采用动物模型约束性最大似然法 (REML)对该猪群的遗传参数进行估计 ,测定 1 1 4 4头纯繁金华母猪的产仔哺育记录。结果表明 ,产仔数 (TNB)、产活仔数 (NBA)、初生重 (PBW)、初生窝重 (LBW)、 2 0日龄头数(NFC)、 2 0日龄窝重 (LWFC)、 2 0日龄重 (PWFC)、 60日龄头数 (NW)、 60日龄窝重 (LWW)、 60日龄重 (PWW)、乳头数 (TN)的遗传力分别为0 1 2± 0 0 9、 0 1 8± 0 1 1、 0 1 5± 0 0 9、 0 0 2± 0 0 9、 0 1 0± 0 1 1、 0 0 8± 0 1 3、 0 1 8± 0 1 0、 0 2 3± 0 1 1、 0 31± 0 1 3、 0 35± 0 1 1和 0 1 9± 0 1 0。TNB与NBA、LBW、NW、LWW的遗传相关范围为 0 66～ 0 88,TNB与PBW的遗传相关为 - 0 43。NBA与LBW、NW、LWW的遗传相关范围为 0 60～ 0 64,NBA与PBW遗传相关为 - 0 63。PBW与PWW的遗传相关为 0 51。     

Genome-wide association study of swine farrowing traits. Part I: Genetic and genomic parameter estimates

The primary objective of this study was to determine genetic and genomic parameters among swine (Sus scrofa) farrowing traits. Genetic parameters were obtained using MTDFREML. Genomic parameters were obtained using GENSEL. Genetic and residual variances obtained from MTDFREML were used as priors for the Bayes C analysis of GENSEL. Farrowing traits included total number born (TNB), number born alive (NBA), number born dead (NBD), number stillborn (NSB), number of mummies (MUM), litter birth weight (LBW), and average piglet birth weight (ABW). Statistically significant heritabilities included TNB (0.09, P = 0.048), NBA (0.09, P = 0.041), LBW (0.20, P = 0.002), and ABW (0.26, P < 0.0001). Statistically significant genetic correlations included TNB-NBA (0.97, P < 0.0001), TNB-LBW (0.74, P < 0.0001), NBA-LBW (0.56, P < 0.0017), NSB-LBW (0.87, P < 0.0395), and LBW-ABW (0.63, P < 0.0002). Genetic parameters are similar to others found in the literature. The proportion of phenotypic variance explained by genomic markers (GP) generated by GENSEL was TNB (0.04), NBA (0.06), NBD (0.00), NSB (0.01), MUM (0.00), LBW (0.11), and ABW (0.31). Limited information is available in the literature about genomic parameters. Only the GP estimate for NSB is significantly lower than what has been published. The GP estimate for ABW is greater than the estimate for heritability found in this study. Other traits with significant heritability had GP estimates half the value of heritability. This research indicates that significant genetic markers will be found for TNB, NBA, LBW, and ABW that will have either immediate use in industry or provide a roadmap to further research with fine mapping or sequencing of areas of significance. Furthermore, these results indicate that genomic selection implemented at an early age would have similar annual progress as traditional selection, and could be incorporated along with traditional selection procedures to improve genetic progress of litter traits.     

Inferring phenotypic causal structure among farrowing and weaning traits in pigs

Direct selection for litter size or weight at weaning in pigs is often hindered by external interventions such as cross‐fostering. The objective of this study was to infer the causal structure among phenotypes of reproductive traits in pigs to enable subsequent direct selection for these traits. Examined traits included: number born alive (NBA), litter size on day 21 (LS21), and litter weight on day 21 (LW21). The study included 6,240 litters from 1,673 Landrace dams and 5,393 litters from 1,484 Large White dams. The inductive causation (IC) algorithm was used to infer the causal structure, which was then fitted to a structural equation model (SEM) to estimate causal coefficients and genetic parameters. Based on the IC algorithm and temporal and biological information, the causal structure among traits was identified as: NBA → LS21 → LW21 and NBA → LW21. Owing to the causal effect of NBA on LS21 and LW21, the genetic, permanent environmental, and residual variances of LS21 and LW21were much lower in the SEM than in the multiple‐trait model for both breeds. Given the strong effect of NBA on LS21 and LW21, the SEM and causal information might assist with selective breeding for LS21 and LW21 when cross‐fostering occurs.     

Estimation of genetic parameters for farrowing traits in purebred Landrace and Large White pigs

Genetic parameters were estimated for six reproductive traits related to farrowing events in Landrace and Large White pigs; total number born (TNB), number born alive (NBA), number stillborn (NSB), total litter weight at birth (LWB), mean litter weight at birth (MWB), and gestation length (GL). We analyzed 62,534 farrowing records for 10,637 Landrace dams and 49,817 farrowing records for 8,649 Large White dams. Estimated heritabilities of TNB, NBA, NSB, LWB, MWB, and GL by single‐trait repeatability model analyses were 0.12, 0.12, 0.08, 0.18, 0.19, and 0.29, respectively, in Landrace, and 0.12, 0.10, 0.08, 0.18, 0.16, and 0.34, respectively, in Large White. Genetic correlation between NBA and NSB was unfavorable: 0.20 in Landrace and 0.33 in Large White. Genetic correlations of GL with the other five traits were weak: from ?0.18 with NSB to ?0.03 with NBA in Landrace, and from ?0.22 with NSB to ?0.07 with NBA in Large White. LWB had a highly favorable genetic correlation with NBA (0.74 in both breeds), indicating the possibility of using LWB for the genetic improvement of NBA.     

Estimation of genetic parameters for reproductive traits in connectedness groups of Duroc,Landrace and Yorkshire pigs in China

The objective of this study was to estimate group- and breed-specific genetic parameters for reproductive traits in Chinese Duroc, Landrace, and Yorkshire populations. Records for reproductive traits between April 1998 and December 2017 from 92 nucleus pig breeding farms, which were involved in the China Swine Genetic Improvement Program, were analysed. Due to weak genetic connectedness across all farms, connectedness groups consisting of related farms were used. Three, two and four connectedness groups for Duroc, Landrace and Yorkshire were firstly established according to the genetic connectedness rating among farms. For each connectedness group a five-trait animal model was implemented, and via restricted maximum likelihood procedure the genetic parameters were estimated for five reproductive traits i.e., total number born (TNB), number born alive (NBA), litter weight at farrowing (LWF), farrowing interval (FI) and age at first farrowing (AFF). The average of heritabilities among connectedness groups ranged from .01 (for FI in Yorkshire) to .30 (for AFF in Duroc). Estimates of repeatability for litter traits ranged from .14 to .20 and were consistent for each breed, and for FI, the estimates varied from .01 to .11 across breeds and groups. The estimated genetic correlations among litter traits (i.e., TNB, NBA and LWF) were all significantly high (>.56) and similar across breeds. Averaged genetic correlations over three breeds were −.25, −.27, −.18, −.04, −.10, −.02, and .28 for FI-TNB, FI-NBA, FI-LWF, AFF-TNB, AFF-NBA, AFF-LWF and FI-AFF, respectively. The standard errors of the estimates were all very low (<0.01) in most situations. Results from this study suggest that selection based on TNB which is currently used in dam line selection index can improve NBA and LWF simultaneously. However, care should be taken on FI and AFF as they are both greatly influenced by non-genetic factors such as management and measurement.     

四川省外种猪雌激素受体基因对繁殖和生长性状的影响

本试验以四川省外种母猪的 3个品种 (大约克、长白、杜洛克 )为研究对象 ,采用PCR RFLPs的方法检测其ESR基因的PvuⅡ多态性 ,分析了该基因与产仔数及生长性状之间的关系。结果表明 :初产胎次中 ,ESR基因型间总产仔数 (TNB)和产活仔数 (NBA)差异极显著 (P <0 .0 1) ,BB和AA纯合子间TNB和NBA分别相差 5 .97和 3.72头 ,基因加性效应分别为每个B基因 2 .98和 1.86头 ;对于经产胎次 ,总产仔数 (TNB)在AA、AB基因型与BB基因型的差异达到 0 .0 1的极显著水平 ,产活仔数 (NBA)在AA基因型与BB基因型间显著差异 (P <0 .0 5 ) ,TNB和NBA母猪每窝BB纯合子比AA纯合子分别多 3.6 8和 2 .89头 ,基因的加性效应为每个B基因分别为 1.84和 1.4 4头。头胎和经产胎次中ESR基因型在初生窝重、2 0日龄头数和窝重、30 / 4 5日龄头数和窝重以及 70日龄窝重之间的差异普遍不显著 (P >0 .0 5 ) ,但是以上 6个性状在ESR基因的 3种基因型间存在BB >AB >AA的趋势     

Comparison of genetic improvement for litter size at birth by direct and indirect selection in swine herd

Responses to selection for number of piglets born alive (NBA) by the total number of piglets born (TNB), the NBA, and the NBA plus number of piglets born dead (NBD) were compared using the accuracy of selection and expected genetic gain calculated from the selection index with family information and the real response to selection, using data generated by Monte Carlo computer simulation. The accuracy of selection for NBA selected by TNB was higher than that by NBA only if the genetic correlation between TNB and NBA was close to 1.0, or the value of heritability for the TNB was much larger than that for the NBA. The accuracy of selection for the NBA selected by the combination of the TNB and the NBA was generally highest in the three selection methods in each family structure. Selection by the TNB resulted in the greatest expected genetic gain for the TNB among the selection methods. In the best linear unbiased prediction (BLUP) selection, the genetic gain for the NBA accumulated by the NBA tended to be similar to that accumulated by the combination of the NBA and the NBD, and both genetic gains at generation 10 were significantly larger than that by the TNB (P < 0.001). The accumulated responses selected by the two‐trait animal model BLUP estimated from genetic parameters with errors were similar to those estimated from the true parameters, and there was no significant difference between them. These results indicate that selection by the NBA or by the NBA and the NBD gives more genetic improvement in the NBA than that by the TNB.