Hoggard says farmers thought the slide in dairy prices over the last few months had bottomed out.
"Everyone has been talking up the chances of prices rising but this is not the case," he told Rural News online.
This morning's GDT event saw the price index down 5.9%.
The biggest fall was recorded by WMP, which is Fonterra's main export.
WMP slumped 10.8% to US$2054/metric tonne. Skim milk powder is down 5.8% to US1875/MT.
Hoggard says the 10.8% drop in whole milk powder prices is the biggest worry.
"It's hard to know the reasons behind today's big fall in prices," Hoggard says.
Key Results from this morning
AMF index up 1.6%, average price US$2,855/MT
Butter index down 0.3%, average price US$2,694/MT
BMP index down 8.1%, average price US$1,878/MT
Ched index down 4.9%, average price US$3,060/MT
LAC index not available, average price not available
RenCas index down 4.1%, average price US$5,901/MT
SMP index down 5.8%, average price US$1,875/MT
WMP index down 10.8%, average price US$2,054/MT
