Thistleyhaugh Farm

High genetic merit sires lift carcase weights and flock profitability at Thistleyhaugh farm

Fast finishing is important at Thistleyhaugh, as Duncan and Angus Nelless race to get their organic lambs finished as efficiently as possible from the clover rich organic cover crops at their disposal.

Supporting RamCompare from its inception nearly 7,000 abattoir records have been collected at the farm to develop and underpin AHDB’s genetic evaluation of carcase traits delivered by Signet. Performance from this forage based system is impressive, producing commercial lambs that across the seasons (good and bad) have resulted in an average carcase weight of 18.2kg at just 117 days of age.

Performance at Thistleyhaugh over time:

Within a fast finishing system you don’t always see big differences in days to slaughter between progeny groups, here the differences tend to be expressed in terms of carcase weight.

Research using data collected by RamCompare farmers shows that Signet have several useful genetic predictors for carcase weight, namely those Estimated Breeding Values (EBVs) for scan weight, muscle depth, lean weight and gigot shape; each of which contribute to our ability to identify sires that will increase the weight of lamb carcases at a given age and their value.

Signet have now gone a step further and produce a breeding value for carcase weight to assist ram buyers to find the most profitable sires for this trait.

The graph below shows how this breeding value related to on-farm performance for the 2024 lamb crop, with a strong relationship seen between the sire’s breeding value and the carcase weight of their progeny.

Over the years, we have seen the impact of what modern genetics can deliver through the fast finishing system that Thistleyhaugh operates. In their final year of commitment to the project, we see the genetics of two particular rams shine through, as expected from their individual breeding values.

The Charollais ram bred by Crogham Charollais was an elite animal identified through the use of Computed Tomography (CT), his genetics for lean meat yield place him in the top 10% of the breed, high genetics of gigot shape the top 1% and as a result he has one of the highest Carcase Weight EBVs in the breed.

Likewise a Meatlinc from George Allison, descended from a line of rams that had been selected using breeding values for CT traits to enhance muscling, whose progeny were half a kilogramme heavier than the flock average at the same slaughter age.

Despite the high average genetic merit of the sire team at Thistleyhaugh, the progeny of these two rams were still producing lambs worth £4.89/head more than the flock average – easily worth an extra £800-£1000 over their lifetime.

Don’t forget their mums

Fast growth rate requires good health, nutrition and the use of sires of high genetic merit – but equally important is the genetic merit of the ewe flock.

At Thistleyhaugh the ewes selected for mating to terminal sires as part of the RamCompare project are the “B team”, the ewes dropped from the Nelless family’s high genetic merit Signet recorded Lleyn flock that have failed in some way to meet the required standard for future purebred breeding.

Yet every year the “B team” get better and better, due to the impressive rates of genetic gain in the Thistleyhaugh Lleyn flock.

Over 26,000 Lleyn lambs have been recorded since 2008, across the flock the genetic potential for growth to 8 weeks has increased by a kilogramme, with similar increases attributable to the selection of ewes with superior genes for milk and maternal care. All this has been achieved, whilst simultaneously lifting the genetic merit of the ewes to successfully rear more lambs.

Improvements in genetics don’t arise overnight or by selecting the best looking ram in the show ring. When it comes to terminal sire breeding, the high genetic merit sires we see today have been developed on the back of decades of AHDB and ram breeder funded investment in ultrasound and CT scanning to find elite genetics – and it is clear from the data at Thistleyhaugh that this is really starting to pay off.

Within maternal breeding programmes breeding decisions are more complex and tend to take longer, but with improved maternal genetics being expressed in the flock year after year – the potential rewards are even greater.

To find out how to select the best terminal sire or maternal ram for your flock read…..

Buying a recorded ram | AHDB