Sheep KPI validation project: phase II



The key performance indicators (KPI) identified by the project are:

  1. Body condition score (BCS) targets at key times (weaning, mating, scanning, lambing, eight week weights)
  2. Change in BCS between the key times
  3. Eight week weight (8WW) of lambs
  4. Combined 8WW for ewes
  5. Percentage of lambs failing to reach 85% of the 8WW target weight
  6. 90 day weight (weaning) of lambs
  7. Combined 90 day weight for ewes

BCS remains a highly repeatable tool which can be used to drive management interventions. The importance of regular monitoring and manipulation of BCS as a means of improving performance is underpinned by the outputs from this project.

There are also strong indications that the effects of BCS on litter size and subsequent eight week weights (8WW) reared/ewe are longer term than previously acknowledged.

There are clear indications that both BCS and weight, and changes in these two parameters are important for performance (litter size and lamb growth rate), particularly in the weaning to scanning period. The two flocks with low BCS initially had improved scanning results in line with improved BCS in mature ewes. Change in BCS/weight from mating to scanning has also consistently been a significant factor and the evidence supports the need for ewes to continue to at least maintain and preferably continue to improve, at least with a weight gain in this period. This is counter to previous advice which allowed for (indeed in some cases recommended) a modest reduction in reduction in BCS (up to 0.5 BCS units) in this period for fit ewes.

The weight of lambs (in particular twins) at eight weeks is an extremely important indicator (KPI) of how well lambs will do over their lifetime, and hence the productivity of the ewe. A target of 20 kgs for the adjusted eight week weight is supported by the data. Sheep farmers should weigh at least a representative sample of lambs at eight weeks of age.
Separate analysis of the performance of shearling ewes in the last two years of the project highlights the difference in shearling performance compared to mature ewes and perhaps unsurprisingly, these differences are significant. The rearing phase plays an important role in the performance of ewes as shearlings. Weight at first mating is of particular significance and further analysis is expected to show a sustained lifetime effect.

Lambs that do not grow well to eight weeks (<17 kg or 85% of the target) continue to struggle up to and beyond weaning.  The percentage of these ‘light lambs’ is developing as a KPI in its own right.  Weaning (adjusted 90 day) weights are heavily influenced by eight week weight, underlining the importance of the early growth period.

Individual BCS and weight data can be reliably recorded on commercial sheep farms using EID and associated equipment and this can now be used to drive important management decisions using commercially available software.

As ewe BCS improves to the target levels and the variation in BCS across a flock falls, ewe weight becomes the more significant measured parameter, presumably because the changes in BCS are not sensitive enough. This does not detract from BCS as the main driver in commercial flocks and nor does it imply that ‘bigger is better’. However, in flocks that have access to automatic drafting systems it may be a way of monitoring short term nutritional effects in groups of animals that would enhance management actions / interventions.

As ewe BCS improves to the target levels and the variation in BCS across a flock falls, ewe weight becomes the measured parameter most likely to have significance because it is more sensitive.
This project has reinforced the need to determine trace element strategies based on risk management.

The results have altered the data collected for RamCompare and lead to Challenge Sheep.  Nerys Wright is currently doing further analysis for her part-time PhD.

Beef & Lamb
Project code:
01 April 2014 - 31 July 2017
AHDB Beef & Lamb
AHDB sector cost:
Total project value:
Project leader:
Nottingham University

About this project

The Problem:

Initial results from the pilot study support the hypothesis that BCS is an important KPI in breeding sheep flocks. However, this is only one year’s data so it is important the project is extended to assess seasonal (and cumulative) effects across successive years to establish robustness and hence applicability/repeatability for the industry. Therefore the project will extend the pilot data by continuing for two more full breeding seasons, and will end in December 2016.


Project Aims:

  • To demonstrate the importance of body conditioning monitoring on ewe and lamb performance
  • To understand which KPIs are more important for these systems
  • To incorporate trace element and worm burden information into flock management



  • Body condition scores will be recorded on individual ewes at critical stages during the production cycle – tupping, scanning, lambing, eight week weight and weaning  The performance of each ewe and her lambs will also be recorded using EID systems so that this can be cross referenced and analysed against BCS. This will be done for each stage of the cycle and against changes in BCS over the cycle
  • Trace element status will be monitored once per year with actions followed up to ensure a cost-benefit
  • Faecal egg counts will be regularly collected via an online system to allow decisions to made based on worm burdens


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