More than three in 10 Dutch cows were kept permanently indoors last year, a slight rise on 2013, the national statistics office CBS said on Wednesday.

In 2001, 90% of Dutch cows grazed at least part of the year on pasture.

Smaller dairy farmers are most likely to put their cattle outdoors. Some 94% of farmers with fewer than 40 animals still do so, the CBS said.

Bigger farms, which use robot milking equipment, tend to keep their cows indoors because they are milked three times a day. Just 49% of farms with more than 160 cows put their animals out to pasture.