Evaporation in barrels?

[Fichina]

I was dumping milk in a barrel for future use, and I just noticed that a decimal of milk had been taken out somehow. Do milk (and other liquids maybe?) evaporate off over time in barrels?

The only other alternative I can think of is the fact that there's a calf nearby. But I'm not aware that they could drink milk out of things that aren't cows....

[sabinati]

calf sappin your milk

[exewu]

place your barrels to the SE of your calves and not on the NE side
I'm not joking

[sabinati]

better yet, place them inside.