Caught Rob and Helen's conversation just now re. feeding the cows spuds over winter.
Scripties ... just in case you are reading this thread, I'll recount an amusing incident that happened to us a few years ago, when we did something like this, in case you want to incorporate it into this story-line. 
OK - there was one year we grew a few tonnes of spuds and didn't manage to sell them all, so we had the bright idea (like Rob) of feeding them to the cows.
Every day we'd drop a few tractor-bucketloads of tatties behind their feed barrier, so they could help themselves. All went well for a few days.
Then ... one morning I switched went round the fold yard to wake up the cows for morning milking. My eyes met with a cow laid out, straining.
At first I wasn't worried, as looking at her due date, she was a week off calving. So I figured she was getting on with it.
I was a bit surprised when at the end of milking she was in the same position and seemed to have made no progress with calving. So I called the vet.
Vet arrived and announced that her cervix hadn't opened at all, so the cow needed a caesarean. She would be back that afternoon with another vet and they'd perform the operation.
Vet +1 came back that afternoon all equipped and ready for the caesarian (our first one ever on-farm). However, just before cracking on with it, they checked her over again one last time, and tentatively asked 'Have the cows had anything to eat in the last few days which they haven't eaten before?' Upon enlightening them, re. the potatoes, they decided that she wasn't calving, she actually just had major tummy-ache and trapped wind from eating too many potatoes. So they drenched her with masses of sunflower oil and left.
Not long after their departure, cow stood up, belched and shat massively and strolled off nonchalantly as if her experience were a normal daily occurrence.
Oh and she calved completely normally a week later .....!