Both carcass yield and meat quality are important indices for beef grade, and consequently they are crucial factors for determining beef consumption and price. However, an optimal slaughter time for satisfying high carcass yield and meat quality has not been systemically evaluated, and identifying the time requires their relationship. Therefore, the objective of this study is 1) to examine the distribution of carcass yield by quality index, and 2) to investigate correlation between factors for judging grades of carcass yield and meat quality. We applied statistical analysis (ANOVA and correlation) for the data of Hanwoo (892 data points: bulls=311, cows=163, steers=418) slaughtered from 1995 to 2006. As a result of ANOVA, the mean difference of carcass yield in quality grade 3 was different with grade 1+, 1, and 2(p<0.05). In the correlation analysis, the meat quality grade showed a positive weak correlation with carcass yield (r=0.259, p<0.05), but was negatively correlated to carcass weight and back-fat thickness which were factors for carcass yield index calculation (-0.225 and -0.154, respectively, p<0.05). The results provide an initial idea for relating carcass yield and quality so that we can use it for determining the optimal time for slaughting.

The study was conducted to investigate the effects of feed withdrawal on gastrointestinal weight, digestive condition, and carcass yield. The effects were studied in 36 HANWOO and 245 pigs. The weight of the gastrointestinal tract decreased with fasting time in both HANWOO and pigs. No significant differences in weight of HANWOO stomachs, intestinal tracts, and carcass yields were observed throughout the experimentals. Among pigs, significant differences in gastrointestinal tract weight were observed when comparing short fasting time (4 h) with long fasting time (above 12 h) (p<0.05). HANWOO and pigs showed no significant differences in carcass yield during fasting times. These results suggested that feed withdrawal for 16 and 12 hours is appropriate for HANWOO and pigs.

The present study hypothesized that ratio between carcass traits components could be applied for the understanding of yield index in Hanwoo steer. A thousand data was generated based on average carcass weight (CW), loin area (LA) and backfat thickness (BT) of Hanwoo steer in December 2018 for analysis 1. Then yield index (YI) was calculated using newly established yield index equation. The correlation between yield index and each carcass traits was visualized. In the interaction between carcass traits components (LA, CW, BT) and YI, only the interactions including BT showed a regular pattern to YI. Then changes of YI according to ratio of carcass traits components were investigated. The observed interactions between LABT and CWBT were similar with Monod equation model. The changes of YI to LABT and CWBT were fitted to Monod equation, and yield constants (K1 for LABT; K2, CWBT) of each equation were calculated as 0.47 and 2.20, respectively. Carcass traits from 5 commercial Hanwoo steer farm were then employed in the second analysis. Yield constants of each farm were estimated. In estimation, R2 value for K1 (LABT) showed greater than the K2 (CWBT). Finally, each farm was plotted based on their K1 and K2 values and it was found that greater yield index of Hanwoo steer was found as increased K1 and K2. As conclusion, the present study suggested the possibility of K1 and K2 values for understanding of yield grade equation and their application in the evaluation of new model for yield grade estimation and feeding strategy.