Fonterra says many farms are inaccessible and milk collection impacted by flooding in Southland and Otago.
A ceremony in Beijing was attended by Prime Minister John Key, New Zealand ambassador to China John McKinnon, Fonterra chairman John Wilson and chief executive Theo Spierings, and representatives of Beingmate, the Ministry of Environmental Protection, the Chinese Academy of Sciences and Tsinghua University.
A plaque was unveiled to mark the first phase of the NZ-China Environment Cooperation Project and the Fonterra-Beingmate deal.
Spierings says the event marked progress in building an integrated business in China.
"Part of this is building partnerships to sustainably develop the dairy industry and to bring safe, high quality dairy nutrition to Chinese consumers," he says.
The three-year NZ-China Environment Cooperation Project was launched by the Chinese and NZ governments, with support from government agencies and Fonterra. The project explored ways to use stock effluent as a fertiliser to maintain crop productivity, improve soil health and protect water quality.
Fonterra and Beingmate signed an agreement to extend their partnership in maternal and infant nutrition and the Anmum brand in China.
Beingmate chairman Wang Zhentai signed on behalf of Beingmate.
"There has been a strong start to our partnership and we look forward to continuing to build on this. Today's celebration reflects our joint ongoing commitment to Chinese consumers and I believe sets a strong example of win-win cooperation for our two nations," says Wang.
Fonterra and Beingmate started their partnership in August 2014, and formalised it in March 2015 when Fonterra bought 18.82% of Beingmate. The two companies then signed a distribution agreement for Beingmate to sell Fonterra's Anmum-branded products in China and jointly own Fonterra's factory at Darnum, Australia.