Almost all cows experience a negative-energy balance in the first few weeks after calving which causes them to lose weight, notes Milo Wiltbank, reproductive physiologist at the University of Wisconsin. However, the severity of this weight loss is what affects the reproductive performance of the cows. As the data above suggest, the greater the loss in body condition between calving and the cow’s first breeding — as measured on the common scale ranging from one to five — the lower the conception rate.

Source: Jim Ferguson, “Diet, production and reproduction in dairy cows,” Animal Feeding Science Technology, 1996.