Background 

Some cattlemen have suggested that feeding distiller’s grains changes the fats within the lean to the extent that intramuscular fat is less visible to the grader. They contend that WDG results in a lower marbling score. This study was conducted to determine if this was the case or not. 

Methodology 

Steers (n=268) were fed 0, 10, 20, 30, 40 or 50% of the diet (DM basis) as modified wet distiller’s grains plus solubles for 176 d prior slaughtering. Forty-eight hours postmortem, marbling score, marbling texture and marbling distribution were assessed by a USDA grader and one ribeye slice (m. Longissimus thoracis) 7 mm thick was collected from each carcass and transferred to the Loeffel Meat Laboratory at the University of Nebraska for fat analysis. The relationship between marbling score and fat content was established.

Findings 

Treatments did not significantly differ (Table 1, 2) in marbling score (0% = Slight, 10% = Slight93, 20% = Small02, 30% = Small01, 40% = Slight95 and 50% = Slight93; P = 0.76). Neither were there differences in marbling distribution (0% = 1.12, 10% = 1.20, 20% = 1.13, 30% = 1.17, 40% = 1.22 and 50% = 1.21; P = 0.71; where 1 = even and 2 = uneven). USDA Choice slices from treatments 0, 10, 20 and 40% had higher values for marbling texture (Table 3) when compared to 30 and 50%, but no consistent pattern was evident (0% = 1.74a, 10% = 1.65 a, 20% = 1.67 a, 30% = 1.42 b, 40% = 1.91 a and 50% = 1.44 b; P = 0.02; where 1 = fine, 2 = medium and 3 = course). Diets did not influence fat content of the ribeye (P = 0.18). For treatments 0, 10, 30, 40 and 50% there were linear relationships between marbling score and fat percentage (Figure 1) in the ribeye (P ≤ 0.05) and all slopes were statically similar at P = 0.45, meaning the relationship between intramuscular fat and marbling score was unrelated to inclusion of MWDGS in the diet. No linear relationship was observed for treatment 20% (P = 0.11).

Implications 

Feeding modified wet distiller’s grains plus solubles (from 0 to 50% of the diet on a dry matter basis) did not alter the amount of marbling deposited within the ribeye. There were no meaningful differences in marbling texture or distribution and the relationship between the amount of fat within the ribeye and the marbling score was similar among all feeding treatments. This means that feeding modified wet distiller’s grains plus solubles does not compromise marbling score or grade.