Data_Sheet_1_THI Modulation of Genetic and Non-genetic Variance Components for Carcass Traits in Hanwoo Cattle.docx

The phenotype of carcass traits in beef cattle are affected by random genetic and non-genetic effects, which both can be modulated by an environmental variable such as Temperature-Humidity Index (THI), a key environmental factor in cattle production. In this study, a multivariate reaction norm model (MRNM) was used to assess if the random genetic and non-genetic (i.e., residual) effects of carcass weight (CW), back fat thickness (BFT), eye muscle area (EMA), and marbling score (MS) were modulated by THI, using 9,318 Hanwoo steers (N = 8,964) and cows (N = 354) that were genotyped on the Illumina Bovine SNP50 BeadChip (50K). THI was measured based on the period of 15–45 days before slaughter. Both the correlation and the interaction between THI and random genetic and non-genetic effects were accounted for in the model. In the analyses, it was shown that the genetic effects of EMA and the non-genetic effects of CW and MS were significantly modulated by THI. No significant THI modulation of such effects was found for BFT. These results highlight the relevance of THI changes for the genetic and non-genetic variation of CW, EMA, and MS in Hanwoo beef cattle. Importantly, heritability estimates for CW, EMA, and MS from additive models without considering THI interactions were underestimated. Moreover, the significance of interaction can be biased if not properly accounting for the correlation between THI and genetic and non-genetic effects. Thus, we argue that the estimation of genetic parameters should be based on appropriate models to avoid any potential bias of estimates. Our finding should serve as a basis for future studies aiming at revealing genotype by environment interaction in estimation and genomic prediction of breeding values.

牛肉牛的体性状表型受随机遗传和非遗传效应的影响，这些效应均可受环境变量如温度-湿度指数（THI）的调节，THI是牛生产中的关键环境因素。在本研究中，采用多变量反应规范模型（MRNM）评估了体重量（CW）、背膘厚度（BFT）、眼肌面积（EMA）和雪花评分（MS）的随机遗传和非遗传（即，残差）效应是否受THI调节，研究样本包括9,318头Hanwoo公牛（N = 8,964）和354头母牛（N = 354），这些牛在Illumina Bovine SNP50 BeadChip（50K）上进行了基因分型。THI的测量基于屠宰前15-45天的时期。模型中考虑了THI与随机遗传和非遗传效应之间的相关性和交互作用。分析结果显示，EMA的遗传效应以及CW和MS的非遗传效应受到THI的显著调节。未发现BFT的显著THI调节效应。这些结果突出了THI变化对于Hanwoo牛肉牛体重量、EMA和MS的遗传和非遗传变异的相关性。重要的是，未考虑THI交互作用的加性模型对CW、EMA和MS的遗传力估计被低估。此外，如果不正确考虑THI与遗传和非遗传效应之间的相关性，交互作用的显著性可能会存在偏差。因此，我们认为遗传参数的估计应基于适当的模型，以避免估计潜在偏差。我们的发现应作为未来研究的基础，旨在揭示在育种价值估计和基因组预测中基因型与环境交互作用的研究。