This may be a factor in the incidence of peripartum disease. A majority of infectious diseases become clinically apparent during the first two weeks after calving. The reduced immune function is certainly a contributing factor in the manifestation of clinical signs during the peripartum period. Reproductive performance is also linked to energy balance. As production has increased over the last 50 years reproductive performance has declined.
Cows are less likely to exhibit estrus if they are in a negative energy balance.
Ova released at ovulation are in the maturation process for about 60 days prior to ovulation. Negative energy balance during this maturation process has a negative effect on ova quality. It is easy to understand then how reproduction becomes more difficult as production levels increase. With all the problems we have just described associated with early lactation, if it wasn't for the fact that early lactation is the most profitable from a milk produced per feed consumed basis, life would be much simpler for the dairy producer if we avoided early lactation. The dairy producers have tried to repeat this period of the lactation cycle as frequently as possible.