The switch is the long whip-like part of the tail that the cow uses to brush flies off of her back, or to swat you in the face if she is annoyed with you while you are milking. LaFonda's beautiful long switch just touched the ground. Some cow, probably she herself, must have stepped on it when she stood up and pulled it off. It won't grow back.
Many dairy farms actually cut their cows' tails short so they aren't getting in the way - and so the farmer doesn't get swatted with a muddy tail a hundred times per milking. But that switch serves an important purpose for bovine comfort during fly season and I suspect it is also a point of pride for the cow. LaFonda looked a bit humiliated this morning and kept tucking her stubby tail between her legs.
I haven't found the switch yet, but after I make the CSA boxes I will search for it in the pasture. I have read about people making prosthetic switches for their cows from horse tail hair, so maybe if I can find it I can re--attach it.