Weaning Calves - Later When Weather Challenges?
I met quite a few dairy farmers at a meeting on March 3 in Lewisburg, Pennsylvania. Most of them have small herds (that is under 100 cows). Nearly all of their calves are reared in cold housing.
We talked some about weaning. The fact emerged that at least half of them had added one to two weeks to their regular weaning program. That is, rather than weaning between 7 and 8 weeks they have been weaning between 8 and 10 weeks during the months of December, January and February.
As we talked about how they made the decision to extend the milk feeding days it seemed clear that weather had been a significant factor. It was not that the winter had been unusually cold in central Pennsylvania. Rather, the weather pattern included many times where there were wide and rapid fluctuations in temperature.
For example, down around 15-19F (-7 to -9C) at night and then 45 -50F (7-10C) by noon the next day. These wide swings seemed to be "normal" for three or more days in a row.
After treating a number of just-weaned calves for pneumonia the practical alternative seemed to be to delay weaning. The reasoning seems to be that the older, larger calves (9 - 10 weeks) were more likely to manage the wide and rapid temperature fluctuations without pneumonia symptoms than younger, smaller calves (7 to 8 weeks).
So, I have no scientific study to share. Just what might be called "folk knowledge" that seems to connect two dots.