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Sion Williams, Bowhill

Exploiting genetic potential to increase carcase weight at Bowhill Estate

By Ed Brant, Signet

Through RamCompare it is evident that gains of £3/£4 per lamb can be achieved through careful ram selection to increase the value of lamb carcases, a large part of which can be attributed to an increase in carcase weight. However, differences of up to 3 weeks in speed of finishing are also an important part of the story of ram performance at Bowhill and should be taken into account when selecting performance recorded rams.


Over the 4 years that Bowhill have been part of RamCompare they have collected records on over 3000 lambs. The 36 rams tested averaged over 75 progeny year, thus producing a really robust data set.

The commercial flock enterprise based at Bowhill, part of the Buccleuch Estate, in Selkirk is a March/April lambing flock that uses maternal Composite ewes sourced via Innovis which are mated to various terminal sire breeds. Lambs are finished from red clover leys and silage aftermath through the summer. Lambs are drawn from 12 weeks of age onwards, selected for slaughter from 40kg liveweight with an objective to kill out at R3L or better.

Sion Williams, Bowhill Estate Manager is seeking to:

  • Identify the rams that will give the best carcase value
  • Increase the number of lambs sold ‘in spec’
  • Enhance the efficiency with which lambs are finished off forage
  • Ensure sustainability and productivity from his ewe flock
Maximising Carcase value

Sion states “One of the keys to improving profitability, is to improve output without increasing costs. Our sheep industry must ensure sustainability and we must therefore maximise production from our commercial ewe flocks.” Ram genetics can help in this objective, with commercial farmers encouraged to focus on areas that can be easily changed through genetic selection, which will have a big economic impact.

There are two routes to increase carcase value:-

  • Increasing carcase weight
  • Increasing the premium paid per kilogram, through enhancements in conformation and fat classification.
Carcase weight

Carcase weight clearly has a major impact on carcase value, as shown in the chart below – which depicts the average carcase weight and carcase value of lambs by different sires. Amongst these sires, there is variation of at least £5/lamb available through careful sire selection – indicating clear potential in financial gains achieved through selecting rams to produce higher carcase weights.

Much of this variation is under genetic control as seen in the second chart – where the genetic merit of the rams used at Bowhill is plotted against the performance of their progeny. The relationship is far from absolute – and this is due in part to another aspect of performance that can be attributed to the genetic merit of the ram, days to slaughter.

Reducing Days to Slaughter

RamCompare has used farm and abattoir data to calculate new Estimated Breeding Values (EBVs), one of which is the Days to Slaughter EBV. This breeding value can be used to select sires whose progeny can be sold earlier.

While this breeding value is only currently produced for rams tested on RamCompare, the Scan Weight EBV – which is available for all performance recorded rams provides an excellent predictor of days to slaughter. Selecting rams with high Scan Weight EBVs will produce lambs that reach slaughter weight sooner.

Superior Sire genetics ensure lambs “hit spec”

“Out of spec” lambs are a commonly cited challenge for the sheep industry, the overall industry figure of 45% of lambs produced in the UK actually fall into a price penalty category at the abattoir. Improving the proportion of lambs sold within target specification, of R conformation or better with a fat class of 2-3L, equates to less waste throughout the supply chain and improved margins to the farmer.

Ensuring that lambs selected meet market specification is important at Bowhill. Lambs are drawn every fortnight from 12 weeks average age, this has ensured that a large proportion are hitting market specification over time. The table shows that over 4 years, Bowhill gets 65% of lambs in spec – a figure that rises to 95% if 3H lambs are included which is an excellent achievement.

Hitting grade specification










































Superior sires making more money

At the end of the day, RamCompare is about assessing value and there is a clear relationship between the value of lambs sold from Bowhill and the genetic merit of their sires. The variation easily worth £3-4 per lamb is clearly visible showing the relationship between these two values is strong.

However, this is only part of the picture – because overall performance needs to take into account days to slaughter. Through plotting each sire’s genetic merit for carcase value against their breeding potential for days to slaughter, a variation of up to a month is clearly seen between high and low performing rams.

There is massive variation within and between breeds, with some of the higher performing rams highlighted on the chart. At Bowhill we see a cluster of rams who combine fast finishing and high carcase values, (bottom right of the chart) with a selection of Meatlinc, Charollais and Texel sires amongst those shown. The two Beltex rams used at Bowhill were leading rams for carcase conformation last year and it is clear they excel in terms of carcase value though for these rams time to finish does take a little longer and this needs to be considered when matching rams to a particular lamb production system.

Remember that RamCompare only uses performance recorded terminal sire rams with top 20% breeding values. These examples demonstrate that a huge potential exists, even within high performing sires, and can improve the efficiency of lamb production systems. Considering EBVs when making ram purchase choices will help to achieve higher value carcases from your lamb enterprise whilst saving time, labour and pressure on available grazing.

When multiplied over 1000s of lambs produced from commercial enterprises across the country this will make a huge benefit to overall sustainability of the industry.

A commerical perspective

Sion comments, “We felt it was important to be involved in the project, which brings together commercial producers with the pedigree breeders who supply rams, in effort to align the industry. This trial has given us a platform to measure the performance of our sheep flock against the sires we are using, whilst at the same time raising awareness of recorded rams for the benefit of the industry.”

“Ram compare has allowed us to monitor the flock in detail and benchmark its output and genetic merit. The project has given us a lot of knowledge about the recording systems and how ultrasound scanning ties into carcass quality.” 

“Using recorded rams, we have found a difference in lamb value of around £5/lamb - echo this over the whole flock it can add £12,500 to the income, whilst at the same time reducing costs by reducing days on farm.”

“At Bowhill we constantly monitor the efficiency of our flock looking to spread the costs of the flock which are generally fixed over ewe numbers. RamCompare opens the opportunity to produce more lambs who are more efficient from that production system with a view to increasing output and therefore making the system more sustainable.” Sion concludes.

Key messages:
  • Identify key areas within your enterprise where genetics can make a difference
  • When using EBVs to select rams remember to focus on:
    • High Scan Weight EBVs will reduce days to slaughter
    • High Scan Weight and Muscling EBVs (like Muscle Depth) will to increase carcase weight
    • High Muscle Depth and CT Gigot EBVs will improve carcase grades
    • Lower Fat Depth EBVs will enable carcases to be taken to heavier weights
  • Regardless of breed, using EBVs to aid ram selection – the variation within a breed often exceeds that between breeds.
  • Gains of £4/lamb might seem small, but over a ram’s working lifetime this could easily be worth an extra £800/ram – more than justifying the extra investment in genetics.
Editors note: 

Sion and the team at Bowhill have been part of RamCompare from the start; originally agreeing to provide two years' worth of data - and ending up providing five. RamCompare is extremely grateful to the team at Buccleugh for the time and energy they have put in to supporting the project. We are especially grateful to Sion - who has made many long journeys down to join the partners meetings, where he has played a major part in helping to shape the project and its outcomes. Sion's time with the project will come to an end this winter, when the last of the 2020 lamb crop are finished and we would personally like to thank him for his contributions to date.