The ASBV system has been inherited from the pig and poultry industries where climate and feed is controlled and as such are strongly linked. Remember inaccuracies of the N.L.W traits are exaggerated by more excessive environmental interference than all other traits.
The first 3 years of Stirling’s trait line were almost entirely E.T transfers from Uardry purchased ewes and semen and so should have replicated close to the Dohne Australia line.
The second year did not, dipping from -0.3 to -3.7. it was drought effected, but so was most of Australia. Stirling has run a whole stud grain ban since 2009. Bin feeding would maintain this trait line but why are the linkages not accounting for this feed difference? They are genetically failing.
In 2014 the Stirling trait line rises dramatically from -4.1 to -0.8, with the Uardry dispersal sheep rising to 40% of the stud, yet the average A.D.W.R of the 20 UD prefix dams is only 0.56 whilst the average A.D.W.R of the 30 ST prefix dams in the 2016 catalogue is substantially higher at 0.61. To maintain accuracy with this the NLW trait should have decreased, instead it has increased dramatically. Climate and feed linkage are failing between properties.
Whilst Stirling day of birth records, most Australian Dohne studs yard mother and centre the birth date producing both growth and NLW inaccuracies.