To resolve this, Corbett changed the pre-set dates on the computer to flag cows at 252 to 254 days of gestation, adding almost a full week to what the previous settings had been. It was also important to have all of the animals moved at the same time, whether they were over-conditioned or not. The goal was to have all of the animals in the close-up pens for at least three weeks before calving. And, all of the cows were placed on a normal close-up ration.
The dietary cation-anion difference (DCAD) of the ration was adjusted to make it negative for the prepartum cows, which helped the cows mobilize calcium from their bones and their digestive tract to the bloodstream. Additional calcium was added to the mineral mix in order to maintain blood calcium levels during parturition.
These changes made a big difference. Metabolic problems cleared up and the cows had a much smoother transition period.
As for the farm owners, “they were very pleased,” Corbett says. “They had been fighting that problem for quite some time.”