Farms within 100 miles of the Canadian border are subject to immigration raids that may leave them unable to milk their cows or harvest their crops.

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The festival has also seen the launch of the not-for-profit Ahimsa Dairy Foundation, which sells milk from cows who will be retired when their milking days are over.

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It chose Guernsey cows for the quality of their milk, which Ms Wakayama has dubbed "golden milk".

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Heat disrupts cows' reproductive cycles, and their milk production goes down, he said.

MSN: Drought may mean fewer, smaller animals at fairs - US news | NBC News

Another problem is that farmers are deciding not to rear replacement cows for their herds, putting future milk supplies under threat.

BBC: Farmers milking their herds

The strict production rules require cows to graze by the place where their milk is turned into cheese, and in this case the ski slopes outside get in the way.

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Dairy cows produce milk for 10 months after they give birth to their calves, and they must be milked every 12 hours.

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