Cows that calve in the fall produce more milk and there is a price differential that favors fall production over spring production. If calving intervals are greatly extended, fall calving cows soon become spring calving cows with a resultant decrease in production and profit. When conception rates are low the use of bulls of lower genetic merit increases because their semen costs less. In some cases clean-up bulls are used extensively. These practices slow the rate of genetic progress, reducing future production potential.
Overconditioned cows have more health and reproductive problems during the subsequent lactation.
The benefits from improving reproductive efficiency obviously cannot be measured directly. It isn't possible to determine the amount of milk a cow fails to produce or the value of a calf that was never conceived. The fact that the economic consequences are not obvious is one reason why herd reproductive efficiency has not received the attention that it should from dairy producers. Even though it is impossible to precisely determine the dollar cost of poor reproductive performance, a reasonably accurate estimate can be made using some assumptions based on experiences in Northeast dairy herds. Following are some examples that will put dollar values on reproductive efficiency.