The market report surprised analysts who had expected an increase as farmers liquidated their herds amid the African swine fever epidemic.

Output had gained slightly in the first three quarters of the year, and high slaughter volumes in the last quarter as farmers tried to cash in herds before being hit by the world's fastest spreading epidemic of African swine fever and before prices fell further had analysts looking for an annual rise.

"I think next year they will adjust the data (again)," said Yao Guiling, an analyst with China-America Commodity Data Analytics Inc, noting that the output figures for 2017 were revised upwards last year.

China's pork production is being closely watched as the world's top consumer of the meat grapples with deadly African swine fever, which is now found in 25 of its provinces and municipalities, stoking expectations of stronger demand for pork and pork product imports.

Pork output fell as the size of China's pig herd declined three percent to 428.17 million head, according to the data from the National Bureau of Statistics.

China is the world's top pork producer, accounting for half of global supply and with all its production consumed locally.

Many farmers are slaughtering their herds as African swine fever cuts prices in major production areas due to restrictions on transporting pigs, leading to worries about a supply shortfall in the second-half of the year.

In 2018, the number of slaughtered pigs fell by 1.2 percent to 693.82 million head, according to the data.

Agriculture ministry data, however, shows that slaughtering by designated companies increased by 9.3 percent in 2018, said Yao, while the national herd was down almost 5 percent in December from the same month of a year earlier.

Pig prices are hovering at multi-year lows across much of the north, reflecting in large part the recent high slaughter volumes and a glut of meat on the market.

Pork output increased by 0.3 percent in the first three quarters, according to previously released statistics bureau data, reflecting a rapid expansion in the country's breeding herd over 2017, said another analyst.

The impact from African swine fever in the final months of the year should not have led to a significant decline in output, the second analyst said, declining to be named because of the sensitivity surrounding government data.

The statistics bureau data also showed beef output grew by 1.5 percent to 6.44 million tonnes in 2018, the highest volume in records going back 20 years, while lamb output rose 0.8 percent to 4.75 million tonnes.

Poultry production rose 0.6 percent to 19.94 million tonnes.

As reported by Dominique Patton