Department of Animal Biosciences, Centre for Genetic Improvement of Livestock, University of Guelph, Guelph, Ontario, Canada.
J Anim Sci. 2018 Jun 29;96(7):2567-2578. doi: 10.1093/jas/sky172.
As a result of selecting for increased litter size, newborn piglets are being born lighter and have a lower chance of survival. Raising fewer pigs to market weight would have a negative impact on the industry and farmer profitability; thus, understanding the genetics of individual growth performance traits will determine whether these traits will play an important role in pig breeding schemes. This study aimed to estimate genetic parameters for individual birth weight (BW), weaning weight (WW), and probe weight (PW) in Canadian-purebred Yorkshire and Landrace pigs. PW is a live weight taken at the time of the ultrasound measurements, when pigs weigh about 100 kg. Data were collected from 2 large and related breeding herds from 2003 to 2015. Four linear animal models were used, which included the following: Model 1-direct additive genetic effect; Model 2-direct additive genetic and maternal genetic effect; Model 3-direct additive genetic and common litter effect; and Model 4-direct additive genetic, maternal genetic, and common litter effect. The model which included all 3 random effects (Model 4) was determined to be the best fit to the data. Low to moderate direct heritability estimates were observed as follows: 0.15 ± 0.03 for BW, 0.04 ± 0.01 for WW, and 0.33 ± 0.03 for PW for the Yorkshire breed; and 0.05 ± 0.01 for BW, 0.01 ± 0.01 for WW, and 0.27 ± 0.03 for PW in the Landrace breed. As expected, the direct heritability estimates increased with age as a result of decreased maternal influence on the trait. Bivariate animal models were also used to estimate genetic and environmental correlations between traits. Strong direct genetic correlations were observed between BW and WW in both breeds. Based on the estimates of genetic parameters, individual BW could be evaluated and considered in breeding programs aiming to increase BW and improve subsequent performance. Different selection emphasis could also be applied on direct and maternal additive genetic effects on BW to optimize the breeding programs and improve selection efficiency.
由于选择增加窝产仔数，新生仔猪出生时体重更轻，存活机会更低。将更少的猪饲养到上市体重将对行业和农民盈利能力产生负面影响；因此，了解个体生长性能性状的遗传基础将决定这些性状是否在猪育种计划中发挥重要作用。本研究旨在估计加拿大纯种约克夏和长白猪个体初生重（BW）、断奶重（WW）和探测重（PW）的遗传参数。PW 是在超声测量时测量的活体重量，此时猪的体重约为 100 公斤。数据来自 2003 年至 2015 年的 2 个大型相关育种群。使用了 4 个线性动物模型，包括以下内容：模型 1-直接加性遗传效应；模型 2-直接加性遗传和母性遗传效应；模型 3-直接加性遗传和共同窝效应；模型 4-直接加性遗传、母性遗传和共同窝效应。确定包含所有 3 个随机效应的模型（模型 4）最适合数据。观察到低至中等的直接遗传力估计值如下：约克夏品种为 0.15±0.03 用于 BW，0.04±0.01 用于 WW，0.33±0.03 用于 PW；长白猪品种为 0.05±0.01 用于 BW，0.01±0.01 用于 WW，0.27±0.03 用于 PW。正如预期的那样，由于性状的母性影响降低，直接遗传力估计值随着年龄的增长而增加。还使用了双变量动物模型来估计性状之间的遗传和环境相关性。在两个品种中，BW 和 WW 之间观察到强烈的直接遗传相关性。基于遗传参数的估计值，可以评估和考虑个体 BW，以在旨在增加 BW 和改善后续性能的育种计划中进行考虑。还可以对 BW 的直接和母性加性遗传效应应用不同的选择重点，以优化育种计划并提高选择效率。
