Three new estimated breeding values (EBVs) for terminal sire breeds have been generated as a result of a major industry sheep breeding initiative.

Developed to help commercial producers select rams, the new EBVS have the potential to produce offspring that are more likely to meet market specification.

Preliminary results from the RamCompare project, which saw more than 4000 ewes mated to 70+ rams covering five breeds, were rated for a range of traits to include eight-week weight, scan weight, muscle depth, fat depth, carcase weight, carcase conformation, carcase fat class and overall carcase merit.

Results rated the performance of the rams – Charollais, Hampshire Down, Meatlinc, Suffolk and Texels – using data collected from their progeny. For some breeds, animals in the top 1% were nominated and for others only the top 25%. Hence, conclusions about breed differences should be made with caution.

The new EBVs cover carcase conformation, carcase fat class and carcase weight and are published within the report for the first time. Other data, such as ultrasound measures of muscle and fat depth have been used to enhance existing EBVs.

Initial results revealed that the progeny from the 10 Charollais rams used showed fairly good on-farm growth rates with breeding lines capable of producing both leaner and fatter progeny as they approach slaughter weight. On-farm muscling across the loin assessed via ultrasound, amongst these particular sires, appeared lower than some of the other breeds on test. However, when it came to overall carcase conformation, the Charollais punched above its weight in terms of both carcase weight and carcase conformation.

The lambs sired by the 10 Hampshire Down rams, expressed early growth rates and well-muscled lambs at scanning time, when muscle depth across the loin was assessed by ultrasound. According to the report, the breed tended to be fatter at a younger age than the continental breeds which may have an impact on days taken to reach slaughter weight. Overall, the Signet report said Hampshire Down-sired lambs are capable of achieving heavy, well conformed carcases, although they have a tendency to be fatter than other breeds on test.

Only five Meatlinc rams were used with the tups selected boasting the highest conformation and yielding animals, according to CT scanning data rather than those with the highest growth rates within the breed. When selecting rams for AI, sire choice was slightly compromised by availability. In general the Meatlinc-sired lambs expressed good on-farm growth rates and produced exceptionally well-muscled progeny at scanning. This attribute was regularly observed across farms. Again, the breed tended to be slightly fatter than the continental breeds on test, with Meatlinc-sired lambs capable of achieving heavy, well conformed carcase weights. However, the selection of Meatlinc rams with superior genes for growth rate may have led to better performance when it came to overall carcase merit.

Some 10 Suffolk rams were used with the progeny showing fast growth rates up to eight weeks and scanning time. The excelled in this attribute which was accompanied by deep muscling across the loin, partly due to their weight at scanning. The breeding lines tested tended to be fatter than the continental breeds being used in the project. However, carcase weights tended to be lower than might be expected, given the high lamb growth rates expressed on-farm and conformation tended to be less extreme than some breeds – although within the Suffolk’s own test there were examples of rams with good genetics for conformation, carcase weight and overall carcase merit.

Finally, the Texel cross lambs assessed had fairly good genes for early growth rate to eight weeks although overall, the growth rates measured on-farm were not as high as some of the rams from other breeds. Likewise muscling across the loin at scanning time tended to be a bit lower, which may have been due to the lambs being smaller. Carcase weights were higher than might be expected given their live weight at scanning and carcase conformation was consistently high. The combination of these two attributes lead to several rams achieving high overall indexes for carcase merit. Texel sired carcases were consistently leaner than those produced by other breeds.

“RamCompare has proven that robust data can be collected throughout the supply chain and this has led to new approaches in assessing the performance of pedigree animals," said Bridget Lloyd, RamCompare project coordinator.

“The new EBVs produced will enable commercial producers to select rams which have the potential to produce progeny that are more likely to meet market specification. Such rams will be used by pedigree breeders to produce more animals with commercially important traits.”

Duncan Nelless, RamCompare farmer from Northumberland, said: “Being part of RamCompare clearly showed me the financial advantage of selecting breeding stock using EBVs and using rams with the right EBVs for my system. I saw differences of £4-5 when using rams with the highest genetic merit compared to others on the trial.”

The results will be updated in May 2018, with the inclusion of a further 1500 carcase records for lambs born in late spring 2017 which were finished later in the year.

Phase two of the project is well underway involving eight farms in England, Wales and Scotland plus a research farm in Northern Ireland. This means more data can be collected on hard-to-measure traits and rams from more breeds are being tested.