Sometimes you just gotta love the fact you don't drink milk. For White stuff read pus. Cows with mastitis produce a lot of pus but hey - it's creamy, it's the same colour as milk, what the heck.
So yeah - bless the Farmers Weekly who reported 40% of Dairy herds have about a sixth of the cows producing gallons of pus
Reading University's advice is
" if you keep the proportion of chronic cows to below 10%, the chances of being penalised are reduced to 9%."
If farmers are caught with too much pus in their milk then it used to get confiscated and turned into milk powder and fed back to the cows ("Doh!") but they are not supposed to do that anymore. Trouble is Government inspectors are very busy and we wonder how often pus laden milk slips through the net. Judging by the statistic that 40% of UK herds have over 15% pus producing cows there doesn't seem to be that much incentive for the poor dairy farmers to bother about it.
"If it ain't broke don't fix it. Folk wouldn't know a pus rich pint if it landed in their porridge. Probably think it were gold top" seems to be the motto.