(Bloomberg) -- California’s milk production in November plummeted as a bird flu outbreak spreads rapidly among herds in the country’s biggest dairy state.

The state produced just under three billion pounds of milk in November, down 9.2% from the same month last year, the US Department of Agriculture said in a Thursday report. Governor Gavin Newsom declared a state of emergency on Wednesday to expedite its response to the outbreak, which has affected about 650 dairy herds.

Estimated national milk production fell 1% year-over-year, with the losses in California partly offset by higher output in states like Texas and Idaho. 

The drops were bigger than expected, with the “lion’s share of the surprise” in California, which saw the largest year-over-year decrease on record, StoneX Group Inc. analysts wrote in a note. The analysts had forecast a 5% decline for the state, and a 0.2% gain nationally.

Class III milk futures traded in Chicago rose as much as 1.9% on Friday. The most-active contract had previously surged to the highest intraday price since late October on Tuesday, before paring gains.

(Updates with prices and analyst comments in fourth paragraph)

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