The race won by Serious Satire was sponsored by Vermaire Racing, a horse ownership and racing company set up by New Zealand cricket captain Brendon McCullum, who was a popular guest as Daffodil Day races ambassador.
Mr Castles said the donations in lieu of gate admission from about 5000 racegoers - commonly regarded as the day's biggest crowd since equine superstar Sunline celebrated her last New Zealand appearance with victory in the Challenge Stakes in 2002 - are expected to boost the races' Daffodil Day contribution to about $20,000.
"To have Kawi win the big Group 1 race in the colours of the Cancer Society was a fairytale really," he said.
It was the first day of the Bostock New Zealand Spring Racing Carnival, the second day on September 19 clashing with what is currently scheduled to be the Hawke's Bay Magpies' sixth Ranfurly Shield defence of the season, against Bay of Plenty, in Napier.
With Saturday's win over 1400 metres behind him, Kawi is expected back to tilt at the Windsor Park Classic, with the hope of going on to become the first horse to win the Spring Carnival's triple crown, in the Livamol Classic on October 3.