Local mare Third Decree (NZ) (War Decree) picked a lucrative day for a big-race breakthrough, going from last to first in the $350,000 TAB Southern Alps Challenge (1600m) at Riccarton on Saturday. It was the second running of the Southern Alps Challenge, which was established last season by Entain and New Zealand Thoroughbred Racing and is restricted to trainers who operate a stable in the South Island. Last year’s inaugural edition was taken out by Matscot (NZ) (Haradasun) for local owner-trainer-breeders Sharon Robertson and Alan Reeves, and on Saturday the…