Objective:

To validate a modified algometer method for assessing mechanical nociceptive threshold (MNT) in lambs before and after specific husbandry procedures under field conditions.

Approach:

• Study Design: Forty-six Merino lambs were randomly allocated to different treatment groups, including control (sham handled) and various marking procedures such as hot knife tail docking and rubber ring castration.

Key Findings:

• Overall median MNT was 3.07 kgf with a significant association between greater body weight and higher absolute imprecision (p = 7 × 10−5).
• Median coefficient of variation (CV) was 12.5%, significantly higher post-marking (p = 0.0003).
• Good intra-operator reliability was demonstrated with an ICC of 0.83 (95% CI: 0.81–0.94).
• Minimum detectable change was calculated at 1.38 kgf.
• A significant reduction in MNT was observed after marking for all groups (p < 0.01).

Interpretation:

The modified algometer method for measuring MNT in lambs demonstrates sufficient precision and responsiveness to detect changes in nociceptive thresholds following husbandry procedures.

Limitations:

• The study was conducted with a limited number of lambs and specific husbandry procedures, which may affect generalizability.
• Field conditions introduce variability that may affect the reliability of the results compared to controlled laboratory settings.

Conclusion:

The study supports the use of the modified algometer for assessing nociceptive thresholds in lambs under field conditions.