"Butter prices again saw the largest fall," according to Castleton. "Oceania butter prices are currently the lowest globally, so the market had been anticipating that they would find some support."
Lactose slipped 0.5 percent to US$917 a tonne.
Meanwhile, butter milk powder rose 0.1 percent to US$2,474 a tonne, while anhydrous milk fat rose 0.2 percent to US$5,316 a tonne.
Skim milk powder rose 2.2 percent to US$2,005 a tonne, while rennet casein rose 3.7 percent to US$5,326 a tonne, and cheddar climbed 4.2 percent to US$3,631 a tonne.
For sweet whey powder, neither an index nor price was available.
The New Zealand dollar last traded at 65.53 US cents as of 2.54pm in New York, compared with 66.01 US cents at the previous close in Wellington.
There were 126 winning bidders out of 178 participating at the 19-round auction. The number of registered bidders was 541, up from 534 at the previous auction.
"There were the same number of winning bidders at this event as at the previous event, though the auction did stretch out to 2 hours and 43 minutes," Castleton noted, adding that the previous event took one hour and 57 minutes. "There was likely some increased competition for some commodities."