Selecting breeding rams from within the flock and basing selection on a series of performance criteria has helped Greenmount College lift carcass weights in ram lambs from its Blackface flock by 1.4kg from 2004 to 2007.
This dramatic shift in carcass weights comes as a result of a change from running the flock as two separate hefts to managing it on a five family basis, reports Steven Johnston, senior beef and sheep technologist at Greenmount. “Moving to the family system has enabled the best performing homebred ram lambs from each family to be used across other families in the flock.”
In addition to the rise on carcass weights, the proportion of carcasses grading R2, R3 and U3 has shown a marked improvement, rising from 48% to 87% in the same time period.
Following these sizeable improvements Greenmount chose to castrate lambs in 2008 to reduce costs. “This resulted in wether lambs achieving market acceptable weights and fat cover from a predominantly grass-based diet, reducing concentrate use and, therefore, cost.”
The five years of cumulative performance recording, has resulted in a delivered benefit of £5.17 a male lamb, he explains. “This comes from 0.3kg additional carcass weight at £2.88/kg, 30% more lambs grading R and better with an average improvement in p/kg of 12p, 23 days less feed used, including using 3kg less silage/lamb at 2.5p/kg and 0.4kg less concentrate a lamb at 21p/kg.”
Overall, in the 360 ewe flock which weaned 429 lambs in 2009, it is estimated that the grading, growth rate improvement and feed saving increased the flock gross margin by more than £1100, he adds.
And, as well as improving growth and carcass traits the five family breeding policy has highlighted the importance of maternal traits to economic performance. “One family capable of rearing a higher number of lambs was identified. The improved productivity of this family results in an increase in income of £7.69 for every ewe put to the ram.
“This improvement in financial terms was worth more than 16 times the output observed from improving confirmation, highlighting the importance of basing selection decisions on recorded information,” explains Dr Johnston.