Red yolks are seen by consumers as sign of extra nutrition, and they command a premium price.
Police in the northern province of Hebei, the place where many of the contaminated eggs have come from, have arrested a man believed to have supplied the dye to farmers. Farmers then mixed the dye with the birds’ feed, according to the Agriculture Ministry.
Local reports indicate that a total of 10,400 ducks have been culled, while 2,025 kg of duck eggs have been destroyed.