The number of giant factory farms in the Netherlands almost tripled between 2005 to 2013, Trouw reports on Friday.

There were 803 giant farms in the country by the end of 2013, compared with 301 in 2005, and experts say they are causing increasing environmental problems, Trouw says.

A mega farm is defined as one with at least 250 cows, 7,500 pigs, 22,000 broiler chickens or 120,000 laying hens.

The growth is spread across the country but is particularly noticeable in Noord-Holland, Gelderland and Friesland, which now each have over 100 so called mega farms.

Noord-Brabant has 259 giant factory farms, making it the centre of the highly intensive farming industry.

Alterra researcher Edo Gies told Trouw dairy farms in particular are growing in size.’Some 30% of cows on mega farms never go outside and I expect that to reach 37% by 2020 as the number of giant dairy farms doubles to around 600.’

Seven out of 10 mega farms cannot dispose of the manure produced by their livestock on their own property and it has to be moved elsewhere. ‘We have to ask ourselves if we want this in a rural area,’ he said. ‘Perhaps these firms would be better placed in an industrial estate or port areas.’