We estimated genetic parameters for two pork production and six litter performance traits of Landrace, Large White, and Duroc pigs reared in Japan. Pork production traits were average daily gain from birth to end of performance testing and backfat thickness at end of testing (46,042 records for Landrace, 40,467 records for Large White, and 42,920 records for Duroc). Litter performance traits were number born alive, litter size at weaning (LSW), number of piglets dead during suckling (ND), survival rate of piglets during suckling (SV), total piglet weight at weaning (TWW), and average piglet weight at weaning (AWW) (27,410, 26,716, and 12,430 records for Landrace, Large White, and Duroc, respectively). ND was calculated as the difference between LSW and litter size at start of suckling (LSS). SV was calculated as LSW/LSS. AWW was calculated as TWW/LSW. Pedigree data for Landrace, Large White, and Duroc breeds contained 50,193, 44,077, and 45,336 pigs, respectively. Trait heritability was estimated via single-trait analysis and genetic correlation between two traits was estimated via two-trait analysis. When considering the linear covariate of LSS in the statistical model for LSW and TWW, for all breeds, the heritability was estimated to be 0.4–0.5 for pork production traits and below 0.2 for litter performance traits. Estimated genetic correlation between average daily gain and backfat thickness was small, ranging from 0.057 to 0.112, and those between pork production traits and litter performance traits were negligible to moderate, ranging from −0.493 to 0.487. A wide range of genetic correlation values among the litter performance traits was estimated, while that between LSW and ND could not be obtained. The results of genetic parameter estimation were affected by whether the linear covariate of LSS was included in the statistical model for LSW and TWW or not. This finding implies the necessity of carefully interpreting the results according to the choice of statistical model. Our results could give fundamental information on simultaneously improving productivity and female reproductivity for pigs.

中文翻译：

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日本长白猪、大白猪和杜洛克猪的猪肉产量和窝产性能性状的遗传参数估计

我们估计了日本饲养的长白猪、大白猪和杜洛克猪的两种猪肉产量和六种窝生产性状的遗传参数。猪肉生产性状为从出生到性能测试结束的平均日增重和测试结束时的背膘厚度（长白猪 46,042 条记录，大白猪 40,467 条记录，杜洛克 42,920 条记录）。产仔性能性状包括活产数、断奶时产仔数（LSW）、哺乳期死亡仔猪数（ND）、哺乳期仔猪成活率（SV）、断奶时仔猪总重（TWW）和断奶时仔猪平均体重。断奶 (AWW)（长白猪、大白猪和杜洛克猪分别有 27,410、26,716 和 12,430 条记录）。ND 计算为 LSW 与哺乳开始时窝产仔数 (LSS) 之间的差异。SV 计算为 LSW/LSS。AWW 计算为 TWW/LSW。长白猪、大白猪和杜洛克猪品种的谱系数据分别包含 50,193 头、44,077 头和 45,336 头猪。通过单性状分析估计性状遗传力，通过双性状分析估计两个性状之间的遗传相关性。当考虑 LSW 和 TWW 统计模型中 LSS 的线性协变量时，对于所有品种，猪肉生产性状的遗传力估计为 0.4-0.5，窝产性能性状的遗传力低于 0.2。平均日增重和背膘厚度之间的估计遗传相关性较小，范围为 0.057 至 0.112，猪肉生产性状和产仔性能性状之间的遗传相关性可忽略至中等，范围为 -0.493 至 0.487。估计了窝产性能性状之间的广泛遗传相关值，但无法获得 LSW 和 ND 之间的遗传相关值。LSW和TWW统计模型中是否包含LSS线性协变量影响遗传参数估计结果。这一发现意味着有必要根据统计模型的选择仔细解释结果。我们的结果可以提供有关同时提高猪的生产力和雌性繁殖力的基本信息。