The first GlobalDairyTrade auction for New Zealand's new dairy season resulted in an overall price fall of 1.3%.
The decline this week was led by a 3.5% fall in butter prices, while whole milk powder fell 1.1%.
Prices were softer than had been expected based on futures prices before the event and might reflect firm New Zealand production over April, ASB senior rural economist Nathan Penny said.
Nationwide production - for all processors - came in 3.1% higher than in April last year. That said, April production was modest compared with other months, accounting for about 7% of annual production.
Mr Penny expected the global butter shortage to remain acute. The boost from firm April production was likely to be short-lived and the bank still expected butter and/or anhydrous milk fat prices to set fresh records over the coming months.