Stress-related hormones in horses before and after stunning by captive bolt gun.

This research investigates the influences of standard slaughter practices on stress-related hormone levels in horses. The study found increased levels of certain stress-related hormones, suggesting compromised animal welfare during pre-slaughter handling.

Objective and Methodology

• The study aimed to understand necessary modifications of stress-related hormones in horses that are subjected to standardized methods of slaughter. This was to determine the impact on animal welfare during pre-slaughter handling.
• Twelve male horses between the ages of three and five years were included in the study. Their blood samples were taken before slaughter in lairage, which is the holding area where animals are kept before being slaughtered, and during exsanguination, which is the process of draining blood after stunning.

Assessment of Stress-related Hormones

• The stress-related hormones under investigation included catecholamines (chemical compounds released by the adrenal glands in response to physical or mental stress), cortisol (also known as the stress hormone), and beta-endorphin (an opioid peptide that functions as a neurotransmitter).
• The concentrations of these hormones were assessed in the plasma samples using the Enzyme-Linked Immunosorbent Assay (ELIA) method.

Observations and Findings

• The study revealed that there was a significant increase in cortisol and catecholamine levels in the horses after stunning for slaughter. On the other hand, the concentration of beta-endorphin didn’t show any significant increase following the stunning process.
• The ratio between norepinephrine and epinephrine (both being types of catecholamines or stress hormones) declined significantly, indicating the higher involvement of the adrenal medulla (part of the adrenal glands that produces catecholamines) in the stress response.
• The findings suggest that the release of beta-endorphin might have a different pattern compared to the release of Adrenocorticotropic Hormone (ACTH) in stressful conditions.

Implications

• The results of this study underline the stressful nature of pre-slaughter handling for horses, as indicated by significant increases in cortisol and catecholamine levels.
• By providing insights into the stress response of horses under slaughter conditions, the study could help in improving practices to ensure better animal welfare.