Serum cortisol concentration in cattle of different genetic groups slaughtered in confinement

Abstract

The objective of this work was to compare the serum cortisol levels among four genetic cattle groups slaughtered in confinement. Thirty-two non-castrated male bovines from four genetic groups were analyzed: Nelore, Aberdeen Angus × Nelore, Caracu × Nelore, and Guzerá × Nelore. The blood samples were collected on the day of weighing (every 28 days) and during the slaughter. Regarding the concentration of serum cortisol, no significant differences were found among the groups during the first, second, and fourth collections. However, during the third collection and at the day of slaughter, respectively, the Nelore group (3.15 ng/dL; 2.98 ng/dL) showed similarity to the Caracu × Nelore (2.02 ng/dL; 2.07ng/dL) and Guzerá × Nelore (2.33 ng/dL; 2.40 ng/dL) groups. Nelore showed a significant difference compared with the Aberdeen Angus × Nelore group (1.21 ng/dL; 1.61 ng/dL). With respect to the overall collection averages, the Nelore group (2.85 ± 0.87 ng/dL) showed greater values than the Aberdeen Angus × Nelore group (1.61 ± 0.87 ng/dL). However, it showed similarities to the Caracu × Nelore (2.06 ± 1.31 ng/dL) and Guzerá × Nelore (2.48 ± 1.16 ng/dL) groups. It was also observed that animals with low cortisol values gained more weight, as demonstrated by the correlation between ADG and the cortisol collection averages (-0.54; p < 0.05). There was no difference among the groups with respect to shearing strength of the meat, and the correlation between this force and the cortisol collection average (0.15; p > 0.05, ns) showed that meat tenderness in the studied groups was not affected.