|ROSENKRANS, JR, C|
Submitted to: Western Section of Animal Science Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 4/13/2005
Publication Date: 6/22/2005
Citation: Flores, R., May, J., Nihsen, M., Looper, M.L., May, K., Hallford, D., Rosenkrans, Jr, C. 2005. Relationships between calf serum metabolites at feedlot entry and subsequent carcass characteristics in Brangus-crossbred calves. Western Section of Animal Science Proceedings. 56:240-242.
Interpretive Summary: American consumers are highly conscience of product quality when purchasing food, thus encouraging beef producers and ranchers to produce animal with high quality carcasses. Current tools for predicting carcass traits, like ultrasonography, are cost- and labor-prohibitive for many farmers and ranchers. Objectives were to determine relationships among serum metabolites at feedlot entry on carcass characteristics at slaughter. Results indicate lactate dehydrogenase activity was lower in steers with Choice carcasses than steers with Select and might be helpful as an early physiological marker of carcass composition. This information is of interest to beef producers, extension personnel, and agricultural professionals who advise beef producers on management practices.
Technical Abstract: Our aim was to determine the relationship between serum metabolites of Brangus-crossbred calves (n = 85; BW = 324 ± 9 kg) at feedlot entry with their subsequent carcass characteristics. Calves were weighed, and blood samples collected 2 d after arrival at the feedlot. Serum samples were analyzed for lactate dehydrogenase (LDH) activities, hemoglobin, protein, creatinine, prolactin, triiodothyronine, thyroxine, cortisol, testosterone, and IGF-I. After harvest, longissimus muscle and ribfat thickness were measured, and USDA quality and yield grades were assigned to each carcass. Sixty-eight percent of carcasses were assigned Choice grade. Carcass distributions among yield grade were 18, 52, and 26%, for yield grade 1, 2, and 3, respectively. Serum LDH activity was lower (P < 0.02) in calves with Choice carcasses than calves with Select carcasses. Similarly, LDH activity was decreased (P < 0.05) in calves with yield grade 1 carcasses versus calves with yield grade 2 and 3 carcasses. Longissimus muscle area was correlated (P < 0.05) with concentrations of prolactin (r = 0.24), triiodothyronine (r = 0.22), and thyroxine (r = 0.35). Other serum metabolites were not related to subsequent carcass characteristics. Heifers had decreased (P < 0.05) concentrations of IGF-I (152 vs 199 ng/mL), and greater (P < 0.01) concentrations of creatinine (2.62 vs 2.08 mg/mL) than steers. However, the percentage of heifers and steers grading Choice did not differ (P > 0.10). These data support previous studies indicating that serum LDH activity could be used as an early physiological marker of carcass composition.