Deadweight sheep price reporting: methodology

AHDB reports deadweight sheep prices each week. This page details the methodology used in producing the report.
With effect from week ending 25 November 2023, AHDB introduced a change to deadweight sheep price reporting to help standardise dressing specifications across the survey. Further information can be found below.

Overview of deadweight sheep prices

Geographical area GB
Type of survey Voluntary
Sheep included Prime clean sheep (new and old season lambs), classified on the EUROP scale, falling within the SQQ industry standard weight band of 12 - 21.5kg deadweight
Data supplier Abattoirs (buyers)
Timing of release Weekly by Wednesday (reporting previous week Sunday to Saturday)
Size of sample Between 30,000 and 60,000 lambs per week (changes seasonally)
Sample size changes Weeks ending 01/09/2018, 10/10/2020 and 20/08/2022

Further information

What is the AHDB deadweight sheep price series?

The survey collects prices for deadweight sheep from a voluntary sample of abattoirs in Great Britain.  The data is collected weekly and published every Wednesday for the previous week (Sunday to Saturday).   Abattoirs submit the price, weight, fat class and conformation of every individual prime sheep procured deadweight, regardless of scheme, breed or organic status.  

The survey aims to provide an indicative price for deadweight sheep classified on the EUROP grid and falling within the SQQ weight band.  The prices shown are in pence per kilogram, excluding VAT and represent the weekly average payable for animals upon delivery to the abattoir, before deductions (e.g. procurement, transport, insurance, inspection, levy).

The deadweight sheep price series is designed to provide an indicative price paid by a sample of abattoirs. It is not designed to be used as a base for future contract prices. The decision on how to arrive at the price to pay for a sheep is entirely a matter between the producer and the abattoir.

What changes have AHDB introduced in November 2023 and why?

It is important to understand that the abattoirs contributing to the survey use a range of dressing specifications.  Historically, the sheep price reporting process has not accounted for variations in carcase dressing between abattoirs, because there has been no research or legislation on which to base this. 

Defra is currently drafting legislation for mandatory sheep carcase classification and price reporting.  This legislation is likely to result in a common dressing specification, with abattoirs either removing or retaining kidney knob and channel fat (KKCF) and diaphragm skirt (DS).   In preparation for this, AHDB was asked to conduct a trial in 2018 to provide sound evidence on how to best adjust between the two proposed dressing specifications.  The results of the trial showed that the application of weight and price adjustments (coefficients) would achieve this.

From week ending 25 November 2023, AHDB is applying these coefficients to the deadweight sheep prices to help standardise the dressing specifications, until legislation is adopted. 

This updated methodology is based on objective statistical criteria.  It improves transparency and accuracy through consistently reporting a price for a lamb with both kidney knob and channel fat and diaphragm skirt removed.

Summary of data collection and results

Weights of KKCF and diaphragm skirt were collected across a range of lamb carcases, representative of the national population. The relationship between the weight of KKCF and diaphragm skirt and various carcase characteristics was examined to determine appropriate approaches to applying weight adjustments (coefficients) for KKCF and DS. The trial focussed on accurate prediction of the weight of the removed parts. The conversion of these to price adjustments is covered at the end of this note.

Kidney Knob and Channel fat (KKCF)

Statistically the best of the approaches examined was the calculation KKCF weight by use of a standard percentage of carcase weight by fat class (using the standard 7-point scale). Only a small reduction in predictive ability (as assessed by correlation) was observed by using a 5-point fat scale, and this will make the future application to a 15-point scale more straight forward.

Diaphragm Skirt (DS)

The weight of diaphragm skirt was largely unaffected by carcase fatness or conformation. Although the best overall prediction was obtained by regression on carcase weight, fat score and conformation together, this was only slightly better than a straight percentage of carcase weight. Given the latter approach is both easy to apply and to understand, a straight percentage of carcase weight is preferred: DS weight (kg) = 0.6378% of CW

Combining coefficients and applying to price adjustments

As the proposed approaches both apply a percentage to carcase weight, they can be combined by simply adding the DS coefficient to each of the KKCF coefficients:

Kidney knob and channel fat and diaphragm skirt coefficients (% of carcase weight) by fat class (5-point scale)

Fat class12345
KKCF 1.38% 1.51% 2.02% 2.86% 5.18%
Diaphragm skirt 0.64% 0.64% 0.64% 0.64% 0.64%
Combined coefficient (used in price survey) 2.02% 2.15% 2.66% 3.50% 5.82%
Worked example - Carcase weight adjustment

Scenario: A fat class 3 lamb has a carcase weight of 20 kg with KKCF and DS on.

Method: [weight of carcase with parts on] x [coefficient] = [weight of carcase with parts off]

Result: 20 kg x (100-2.66)/100 = 19.468 kg

Therefore, a fat class 3 lamb carcase weighing 20 kg with the parts on would weigh 19.468 kg with the parts off

When applying the coefficients to price, the aim is to equalise the price a carcase would receive regardless of dressing specification.  Because price is quoted in p/kg and the coefficient is a percentage of carcase weight, the coefficient (for each fat class) can be simply applied to the p/kg to adjust it for differences in carcase weight between the two prices.

Worked example - Price adjustment

Scenario: Based on our fat class 3 lamb with a carcase weight of 20 kg with KKCF and DS on (carcase weight 19.468 kg with the parts off), assume a price of 500p/kg with the parts on.  

This would result in a carcase value of £100 per head (20kg x 500p/kg)

Method 1: [£/head] / [weight of carcase with parts off] x [conversion to pence] = [p/kg with parts off]

Result 1: £100 / 19.468 kg x 100 = 513.7p/kg

OR (in a single step)

Method 2: [p/kg with parts on] x [coefficient] = [p/kg with parts off]

Result 2: 500p/kg x 100/(100-2.66) = 513.7p/kg

Therefore, a fat class 3 lamb carcase priced at 500p/kg with the parts on would be priced at 513.7p/kg with the parts off

For more details on the research work that underpins these coefficients, visit the webpage below: 

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

How does this updated methodology affect the price series?

Based on historical analysis of the price series, this change will increase the reported price per kilo by approximately 0.2 - 0.5%, dependent on the make-up of our pricing sample in any given week.

We recommend caution when making historical comparisons following this methodology change.

What does the term deadweight mean?

Deadweight refers to an animal when it is procured directly by an abattoir. The price is paid on the carcase of the animal once it has been slaughtered and dressed. Deadweight pricing differs from liveweight pricing - liveweight refers to an animal purchased through an auction market.

What does SQQ stand for?

SQQ stands for Standard Quality Quotation and refers to a GB industry-standard weight band. For deadweight price reporting, this band applies to the carcase of dressed prime clean sheep weighing from 12 kg to 21.5 kg. 

The deadweight SQQ is sometimes reported in two further weight bands:

  • Standard: 12 kg up to 16.5 kg (deadweight)
  • Medium: 16.5 kg up to and including 21.5 kg (deadweight)

Please note that the SQQ weight band for liveweight sheep sold through auction markets differs from the weights above. This is because it applies to the weight of a live sheep.

Who contributes to the survey?

There is currently no legislation in place for mandatory price reporting and so the prices are taken from a voluntary sample of abattoirs across Great Britain. Defra is currently considering drafting legislation for mandatory sheep carcase classification and price reporting in the future.

What sheep are included in the survey?

Prime clean sheep (with no permanent incisor teeth erupted) are included.  While there is currently no legislation in place for carcase classification, the voluntary sample of abattoirs all report on the industry EUROP classification scale.

Sheep are included in the survey irrespective of scheme, breed or organic status.

A clean sheep is a sheep that has not been used for breeding. Clean sheep are classified as new or old season lambs or mature sheep. Only new or old season lambs are included in the survey.

What sheep are not included in the survey?

The weekly prices do not include:

  • Liveweight purchases
  • Breeding ewes
  • Breeding rams
  • Mature clean sheep with permanent incisor teeth erupted
  • Sheep paid on a flat rate (i.e. where an agreed price is paid on all sheep in the lot regardless of the abattoir’s classification EUROP grid)
  • Contract kills where an abattoir is paid a fee to kill a sheep with no sale taking place

What is a new season lamb?

A new season lamb is a prime clean sheep (male or female) from this year’s crop (born January to September in the current calendar year), with no permanent incisor teeth erupted, and that has not been used for breeding. In GB, the majority of lambs are born in the spring, but a smaller number are also born in the last three months of the previous year (intended for earlier marketing). New season lambs are sometimes referred to as spring lambs.

What is an old season lamb?

An old season lamb is a prime clean sheep (male or female) from last year’s crop (born the previous calendar year, January to September), with no permanent incisor teeth erupted and that has not been used for breeding. Old season lambs are sometimes referred to as hoggs or hoggets.

When do AHDB report new and old season lambs?

Generally, old season lambs are reported from 1 January up until the third Monday in May, then new season lambs for the remainder of the year. 

During May and June each year, new season lamb stock begins to replace the old season lamb stock. If there is enough new or old season lamb data collected in the survey to enable AHDB to report prices, both price series will be available in the AHDB webpage tables. When viewing prices during this time, remember that a new season lamb is a different product to an old season lamb, as they were born in different years and so will achieve different prices.

Contact us

The deadweight sheep prices are produced by our Data and Analysis Team. If you need any further help, please email us at