Cow suddenly drying up - could it be plants?

[ArkMama]

My Holstein suddenly went from giving 3 gallons a day (plus feeding her calf) to just under 1/2 gallon a day. She seems healthy enough, but the milk has just vanished - there one day, gone the next. I'm wondering if she's nibbling on something that's making her milk dry up, but I haven't been able to find a list of plants that will dry up a cow's milk. Can anyone help me out?

[rosalind]

How long has your cow been in milk? How long have you been sharing with the calf?

A cow can hold up her milk and refuse to give it to you, if she wants to save it for her calf.

[Oakshire_Farm]

She could be in heat? how long has she been in milk??? if it goes back up in a day or two that could be it.

[Waiting Falcon]

Another calf nursing ...free dairy bar?

[domino]

I read on another forum where they had milk missing and it was the neighbors stealing the milk!

[Lazy J]

Could it be a combination of decreased nutrient uptake along with increased milk consumption by the nursing calf?