Too many cows, not enough hay

There are more cows here than you think.  Look beyond Babe, the big fat Hereford on the left, and you will see the shoulders of Bonnie-the-Jersey-cow.  There are also two four-month-old calves, George and Gracie, on the other side of the hay ring, and Bonnie's calf, Crystal, is out of the picture on the right.  Eight head of cattle.  Of course the biggest animals eat the most.  
On a side note, notice how big Red-the-bull is, in the above picture.  

Red wasn't nearly as big in this picture

Now he is as tall as Bonnie and almost as tall as Jody.  We don't expect him to have any problem breeding them, since he somehow managed to score with big old Babe.
We feed the cows in an electric-fenced enclosure that the horses can't get into, since horses don't need all that rich alfalfa hay.  Their owner, Adam, comes to feed them every day.  We thought we had a plentiful supply of hay, but that was before we bought Red-the-bull and George and Gracie.  We have begun to wonder if our hay supply will last until spring.  Because of the drought last year, big hay bales that would normally sell for $50 now bring $100 and more.  People are selling four-year-old grass hay for ridiculous prices.  Some farmers have baled dry cornstalks and are selling those bales for thirty dollars and more.  
It's just too easy for our cows to stand right there waiting until they feel like eating some more.  Imagine yourself in a room with a table, covered by plates full of your favorite foods; as soon as you empty the plate, somebody fills it up again.  You know, kind of like that period from Thanksgiving to New Year's.  
Yeah, it's like that.  
We decided to put the cows on a diet.  
Cliff rigged a gate at the entrance to the hay-ring area.  Every evening around sunset I chase the cows out and shut the gate; at daylight next morning I call them up and let them in to eat.  Because George and Gracie are so young, and have no milk to supplement their diet, I bring them up to the barn overnight where they can continue to eat all the hay they want.
There's already a noticeable difference in how fast the hay disappears.  Here's hoping, not for an early spring with all the problems that would bring, but for a timely, wet, grass-growing spring!