I have one Jersey customer who runs into energy issues with the feed every year at about this time and it lasts for a month or so and then goes away. He's had "twins" like this more than a few times over the years that we've pegged as being related to the feed problem. There have been two undeniable cases that were confirmed by managers and five or so cases of "extra" calves where one of the workers swears it came from a particular cow that was already fresh.
From my point of view, I see a good solid heat on his cows and then a weaker heat nine to eleven days later. After the second set of these were born we started paying closer attention and finally concluded that some cows were showing heat on the top of the follicular waves of both horns with the dominant horn showing the best heat.
What's suposed to happen is the cow cycles on one ovary while the other one builds a corpus lutium to assist in pregnancy maintenance. In this guys herd some of his better cows were showing mild heats on the weaker ovary and in a few instances were able to maintain a second pregnancy on it.
