The global dairy industry is gathering in Auckland this week for the biggest event in its calendar.

Jeremy Hill, NZ branch president of the International Dairy Federation, calls the World Dairy Summit the world cup of dairying.

The summit, which runs until Thursday, sets out to stimulate debate and provide the latest information for industry players.

"We do need sector-wide collaboration ... the individual standing committees and action teams meet throughout the year but this is the one time in the year where everybody comes together in the same place," Hill said.

Up to 1700 delegates from 66 countries are expected to attend the annual summit, which was last held in New Zealand in 2001, including from dairy companies, manufacturers, academia, regulatory bodies and government.

"With 800 in Berlin [last year] we were hoping for a minimum of 600 to come to Auckland and so we're just absolutely delighted with the attendance," Hill said.

"That provides the foundation for a fantastic summit."

Sustainability will be a key element of all sessions.

"Here I think we've got to look at sustainability in the broader context," Hill said.

"It is a huge topic but it's not just the context of environmental sustainability, we need to think of it in terms of food security, as sustainable nutrition, sustainable industry development and the employment that provides, and then of course the sustainable environment which is about land use, water use, emissions and so on."

A dairy leaders' forum today would set the scene for presentations during the next three days, with a panel including the chief executives from Fonterra, FrieslandCampina, Amcor and the National Milk Producers Federation.

"If people can leave the summit with stronger connections, a clearer and more robust consensus around the key issues then this has been a big success."

The summit attracts protests every year. "It's a free country, everybody's entitled to their opinion and that's healthy but we need to consider the issues in the broader context because they're not simple," Hill said.

"It's very easy to take a simplistic view along a particular line of thought ... but we're here to create a system which can provide a sustainable source of nutrition to the world's population."

Topics at the summit included sustainability, economics, innovations and bioactives.

Summit convener Andy Williams said: "I think you'd struggle to find a part of the industry that's not covered in some shape or form."

Simon Terry, executive director of the Sustainability Council, said the dairy industry here was not delivering on a promise of sustainability.

Greenhouse gas emissions from the dairy sector had increased since 1990 but it had not embraced low-cost mitigation options, with nitrification inhibitors the most obvious, Terry said.

"It's actually a net profit to farmers because they cut back on urea fertiliser as a result of applying the inhibitor," he said.

A Ministry of Agriculture and Forestry report in March updating progress under the Dairying and Clean Streams Accord showed that during the 2008-09 financial year the level of "significant non-compliance" nationally with farm effluent rules designed to stop effluent flowing into streams and rivers was 15 per cent, up from 12 per cent the previous season.

Fonterra described the result as unacceptable and announced plans to check the effluent management infrastructure of every farm, every year.

The dairy co-operative at the weekend published an open letter from chairman Sir Henry van der Heyden and chief executive Andrew Ferrier that said the co-operative was committed to working with its farmers, staff, customers, government, local authorities, iwi and the community "to ensure good practice is the only practice".