Gajaweera Chandima, Kang Dong Hun, Lee Doo Ho, Kim Yeong-Kuk, Park Bo Hye, Chang Sun Sik, Kim Ui Hyung, Lee Seung Hwan, Chung Ki Yong
Division of Animal and Dairy Science, Chungnam National University, Daejeon 34134, Korea.
Department of Animal Science, Faculty of Agriculture, University of Ruhuna, Matara 81100, Sri Lanka.
J Anim Sci Technol. 2023 May;65(3):596-610. doi: 10.5187/jast.2023.e38. Epub 2023 May 31.
Focusing high marble deposition, Hanwoo feedlot system uses high-energy diet over the prolonged fattening period. However, due to the individual genetic variation, around 40% of them are graded into inferior quality grades (QG), despite they utilized the same resources. Therefore, focusing on development of a nutrigenomic based precision management model, this study was to evaluated the response to the divergent selection on genetic merit for marbling score (MS), under different dietary total digestible nutrient (TDN) levels. Total of 111 calves were genotyped and initially grouped according to estimated breeding value (high and low) for marbling score (MS-EBV). Subsequently, managed under two levels of feed TDN%, over the calf period, early, middle, and final fattening periods following 2 × 2 factorial arrangement. Carcasses were evaluated for MS, Back fat thickness (BFT) and Korean beef quality grading standard. As the direct response to the selection was significant, the results confirmed the importance of initial genetic grouping of Hanwoo steers for MS-EBV. However, dietary TDN level did not show an effect ( > 0.05) on the MS. Furthermore, no genetic-by-nutrition interaction for MS ( > 0.05) was also observed. The present results showed no correlation response on BFT ( > 0.05), which indicates that the selection based on MS-EBV can be used to enhance the MS without undesirable effect on BFT. Ultimate turnover of the Hanwoo feedlot operation is primarily determined by the QGs. The present model shows that the initial grouping for MS-EBV increased the proportion of carcasses graded for higher QGs (QG1 and QG1) by approximately 20%. Moreover, there appear to be a potential to increase the proportion of QG 1 animals among the high-genetic group by further increasing the dietary energy content. Overall, this precision management strategy suggests the importance of adopting an MS based initial genetic grouping system for Hanwoo steers with a subsequent divergent management based on dietary energy level.
韩牛育肥系统着重于大理石花纹的高度沉积，在较长的育肥期使用高能日粮。然而，由于个体遗传变异，尽管它们利用相同的资源，但约40%的牛被评为劣质等级（QG）。因此，本研究聚焦于基于营养基因组学的精准管理模型的开发，评估在不同日粮总可消化养分（TDN）水平下，对大理石花纹评分（MS）遗传价值的差异选择反应。总共111头犊牛进行了基因分型，并根据大理石花纹评分的估计育种值（高和低）（MS-EBV）初步分组。随后，在犊牛期、育肥前期、中期和后期按照2×2析因设计，在两种日粮TDN%水平下进行管理。对胴体进行MS、背膘厚度（BFT）和韩国牛肉质量分级标准的评估。由于选择的直接反应显著，结果证实了韩牛阉牛基于MS-EBV进行初始遗传分组的重要性。然而，日粮TDN水平对MS没有影响（P>0.05）。此外，也未观察到MS的基因-营养互作（P>0.05）。目前的结果表明对BFT没有相关反应（P>0.05），这表明基于MS-EBV的选择可用于提高MS，而不会对BFT产生不良影响。韩牛育肥场运营的最终周转率主要由质量等级决定。目前的模型表明，基于MS-EBV的初始分组使评为较高质量等级（QG1和QG2）的胴体比例提高了约20%。此外，通过进一步提高日粮能量含量，高遗传组中QG1动物的比例似乎有增加的潜力。总体而言，这种精准管理策略表明，对于韩牛阉牛采用基于MS的初始遗传分组系统，并随后根据日粮能量水平进行差异管理具有重要意义。
