A Study on the Estimation of Environmental Effects of Hanwoo Steers Carcass Traits

다국어 초록 (Multilingual Abstract)

This study was conducted to investigate the effects of environmental factors on the carcass traits of Hanwoo cattle. We collected carcass data of 1,703,304 animals of castrated cattle, which were raised by Korean beef farmers nationwide from 2009 to 2019 and registered as pedigree with the Korea Animal Improvement Association and Korea Livestock products Quality Evaluation Institute. The final data used for the analysis after pre-removal of missing and outliers were the slaughter data of 970,567 animals slaughtered from farmhouse 4,040, and four traits were considered: Carcass Weight (CW), Eye Muscle Area (EMA), Backfat Thickness (BF), and Marbling Score (MS). In this study, in order to extract more than the appropriate number of samples from 970,141 animals slaughter data , 600 out of 4,040 farms were simply random sampled and all slaughter data of selected farms were extracted. In addition, to increase the accuracy of variance analysis, samples were extracted by repeating 10 times using the SURVEY SELECT procedure of the SAS statistical program (package ver 9.3) and used for analysis. In the general analysis, to determine the normality of the data by analyzing the generality of each breeding trait, the SAS UNIVARIATE procedure was used to test the Komogorov-Smirnov statistic (D) for each trait to determine whether it was close to the normal distribution. All carcass traits were confirmed to follow a normal distribution based on normality tests. Multivariate analysis of variance (MANOVA) was performed on factors such as slaughter age, production region, slaughter year, and slaughter season using the PROC GLM (Generalized Linear Model) in SAS Package Ver 9.1.3 Service Pack 4. The results of significance tests revealed that all factors, including farm, slaughter year, slaughter season, and slaughter age, had highly significant effects (p<0.01) on all carcass traits. Additionally, carcass performance was influenced by the timing of slaughter, data size, and the level of fixed effects. The results of this study, based on national farm data, provide valuable estimates of environmental effects, serving as foundational data for genetic evaluation of cows in commercial farms. Thus, this information is expected to be directly applicable to improving cow breeding programs.