Association of ultimate pH and stress-related blood variables in cattle.

The objective of this study was to investigate the relationship between ultimate pH (pHu) and stress-related blood variables. Of 50 cattle in total, blood samples from 6 cattle which exhibited high (≥6.10) pHu (dark-cutting) were collected, along with the same number of low pHu and intermediate pHu cattle (5.40-5.80; 5.80-6.10, respectively) to determine the concentration of plasma cortisol, glucose, lactate, creatine kinase, lactate dehydrogenase, haptoglobin and serum amyloid A protein. Compared to cattle with low pHu, high pHu cattle showed higher plasma cortisol, glucose, lactate, creatine kinase and lactate dehydrogenase levels at exsanguination. But the concentration of haptoglobin and serum amyloid A protein showed no significant differences among three pH groups. These results imply that measuring plasma cortisol, glucose, lactate, creatine kinase, or lactate dehydrogenase levels at exsanguination may be useful to identify the dark-cutting beef condition.