236 Preliminary analysis of the relationship between heart score and carcass value in Angus cattle.

Abstract This study aimed to develop a preliminary understanding of the relationship between heart scores (HS) and carcass value in Angus steers. One significant economic consequence of right heart failure in cattle is mortality before slaughter; however, the economic impact of heart remodeling on carcass performance in animals that survive to slaughter is less understood. Carcass value, HS, back fat depth (BF; mm), marbling score (MARB), hot carcass weight (HCW; kg), ribeye area (REA; cm²), and calculated yield grade (CYG) were collected from 299 Angus steers at slaughter. The steers originated in southeastern Wyoming and were harvested between January 2023 and October 2024. Heart scores indicate the severity of right heart remodeling on a scale from 1 to 5, where 1 represents a normal heart with no remodeling, and 5 indicates a heart with severe remodeling. Carcass values were determined using a quality-based Angus grid. Of the 299 scored steers, the HS distribution was 128, 116, 44, 8, and 3 for scores 1, 2, 3, 4, and 5, respectively. Carcass values ranged from $2567.04 to $3146.01, with a mean of $2572.25 and a standard deviation of $245.49. All linear regression models included categorical fixed effects of HS and kill date. When the kill date was held constant, the average differences in carcass value for animals with HS of 4 compared to HS of 1, and those with HS of 5 compared to HS of 1, showed decreases of $161.51 and $345.31, respectively (P = 0.04; P = 0.007). When adjusting for HS, four of seven kill dates had significant effects on carcass value compared to the reference date, with a range of effects from $186.61 to $353.75 (P < 0.05). Linear regression models with outcome variables of BF, MARB, HCW, REA, or CYG were fitted to investigate potential HS relationships with carcass characteristics that can contribute to carcass value. Heart score did not have a statistically significant effect on CYG or MARB (P = 0.21; P = 0.65). When adjusted for kill date, there was a statistical tendency for HS effects on REA (P = 0.08) and BF (P = 0.06). After accounting for kill date, HCW for animals with HS of 4 compared to HS of 1 and HS of 5 compared to HS of 1 had average decreases of 31.82 kg and 60.56 kg, respectively (P = 0.01; P = 0.002). The relationship between HS and carcass value, as well as HCW, indicates a potential economic loss in carcass value due to the negative effects of severe heart remodeling on HCW. Further research is required to gain a comprehensive understanding of how HS affects carcass value in beef cattle.