Establishing coefficients for the weight of kidney knob and channel fat (KKCF) and diaphragm skirt in lamb carcases

Following consultation with the industry in 2018, Defra are considering the introduction of legislation for mandatory sheep carcase classification and price reporting. This would require standardisation of carcase presentation (dressing) for classification and weighing.

Based on industry feedback, it is likely that two carcase presentations will be permitted with the difference in dressing between them being the inclusion or exclusion of kidney knob and channel fat (KKCF) and the diaphragm skirt (DS).

Removal of these additional parts by a plant will require each carcase to have an adjustment applied to correct the weight/price back to the reference dressing specification through the use of a coefficient for official reporting.

AHDB was asked to carry out a trial to provide independent evidence to inform a decision on the appropriate approach to applying a coefficient.

The objectives of the trial were:

1. To determine the weight of KKCF and diaphragm skirt across a range of lamb (new and old season), representative of the national population.
2. To evaluate the relationship between the weight of KKCF and diaphragm skirt and carcase characteristics.
3. To recommend appropriate approaches to applying weight adjustments (coefficients) for KKCF and DS when they are removed from the carcase before weighing.

Analysis of the results determined adjustment factors according to a number of different approaches, all of which are presented in the report.

The final selection of the approach to be used in the possible legislation will be based on a combination of statistical parameters and pragmatic considerations (e.g. ease of explanation and transparency).

Read the summary of responses to the Defra consultation carried out in 2018

Acknowledgements

The cooperation of the processing plants and their staff was key to successful delivery of this project and AHDB are grateful for their assistance.