Hickmann Felipe M W, Braccini Neto José, Kramer Luke M, Huang Yijian, Gray Kent A, Dekkers Jack C M, Sanglard Leticia P, Serão Nick V L
Department of Animal Science, Iowa State University, Ames, IA, United States.
Department of Animal Science, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
Front Genet. 2021 Aug 4;12:707870. doi: 10.3389/fgene.2021.707870. eCollection 2021.
Porcine Reproductive and Respiratory Syndrome (PRRS) is historically the most economically important swine disease worldwide that severely affects the reproductive performance of sows. However, little is still known about the genetic basis of reproductive performance in purebred herds during a PRRS outbreak through the comparison of maternal and terminal breeds. Thus, the objective of this work was to explore the host genetics of response to PRRS in purebred sows from two breeds. Reproductive data included 2546 Duroc and 2522 Landrace litters from 894 and 813 purebred sows, respectively, which had high-density genotype data available (29,799 single nucleotide polymorphisms; SNPs). The data were split into pre-PRRS, PRRS, and post-PRRS phases based on standardized farrow-year-week estimates. Heritability estimates for reproductive traits were low to moderate (≤0.20) for Duroc and Landrace across PRRS phases. On the other hand, genetic correlations of reproductive traits between PRRS phases were overall moderate to high for both breeds. Several associations between MARC0034894, a candidate SNP for response to PRRS, with reproductive performance were identified (-value < 0.05). Genomic analyses detected few QTL for reproductive performance across all phases, most explaining a small percentage of the additive genetic variance (≤8.2%, averaging 2.1%), indicating that these traits are highly polygenic. None of the identified QTL within a breed and trait overlapped between PRRS phases. Overall, our results indicate that Duroc sows are phenotypically more resilient to PRRS than Landrace sows, with a similar return to PRRS-free performance between breeds for most reproductive traits. Genomic prediction results indicate that genomic selection for improved reproductive performance under a PRRS outbreak is possible, especially in Landrace sows, by training markers using data from PRRS-challenged sows. On the other hand, the high genetic correlations with reproductive traits between PRRS phases suggest that selection for improved reproductive performance in a clean environment could improve performance during PRRS, but with limited efficiency due to their low heritability estimates. Thus, we hypothesize that an indicator trait that could be indirectly selected to increase the response to selection for these traits would be desirable and would also improve the reproductive performance of sows during a PRRS outbreak.
猪繁殖与呼吸综合征（PRRS）在历史上一直是全球经济影响最为重大的猪病，严重影响母猪的繁殖性能。然而，通过比较母系品种和终端品种，在PRRS疫情期间纯种猪群繁殖性能的遗传基础仍鲜为人知。因此，本研究的目的是探索两个品种纯种母猪对PRRS反应的宿主遗传学。繁殖数据包括分别来自894头和813头纯种母猪的2546窝杜洛克仔猪和2522窝长白仔猪，这些母猪有可用的高密度基因型数据（29,799个单核苷酸多态性；SNP）。根据标准化的产仔年份周估计值，数据被分为PRRS前、PRRS期间和PRRS后三个阶段。在PRRS各阶段，杜洛克和长白猪繁殖性状的遗传力估计值较低至中等（≤0.20）。另一方面，两个品种PRRS各阶段之间繁殖性状的遗传相关性总体为中等至高。鉴定出了对PRRS反应的候选SNP MARC0034894与繁殖性能之间的若干关联（P值<0.05）。基因组分析在所有阶段检测到的繁殖性能数量性状位点很少，大多数解释的加性遗传方差比例较小（≤8.2%，平均为2.1%），表明这些性状是高度多基因的。在一个品种和性状内鉴定出的数量性状位点在PRRS各阶段之间没有重叠。总体而言，我们的结果表明，杜洛克母猪在表型上比长白母猪对PRRS更具弹性，大多数繁殖性状在品种间恢复到无PRRS状态的性能相似。基因组预测结果表明，通过使用来自受PRRS攻击母猪的数据训练标记，在PRRS疫情下对提高繁殖性能进行基因组选择是可能的，特别是在长白母猪中。另一方面，PRRS各阶段之间与繁殖性状的高遗传相关性表明，在清洁环境中选择提高繁殖性能可以改善PRRS期间的性能，但由于其遗传力估计值较低，效率有限。因此，我们假设，一个可以间接选择以增加对这些性状选择反应的指示性状将是可取的，并且还将改善PRRS疫情期间母猪的繁殖性能。
