The most accurate way to calculate a herd's pregnancy rate is to multiply the percent of cows eligible to be bred that are actually bred times the percent bred that actually become pregnant for a given time period, typically 21 days. The goal should be to have an average 21-day pregnancy rate greater than 20%.
Anything below 20% means lost income potential. Losses come from decreased milk production, an increased cull rate, increases in semen expense, veterinary expenses and over-conditioned cows. These costs are coupled with a reduced ability to cull cows, sell heifers, grow the herd internally, a reduced number of calves born each year and increased herd health risks from potentially needing to purchase cattle.
The most common culprit behind low pregnancy rates is not enough heat detection taking place, says Rob Goodling, extension associate with the Penn State Extension Dairy Team. He points out that this includes herds that use synchronization protocols.
"If a herd can take its pregnancy rate from 14% to 20% they can add $90 to $100 per cow per year to the herd," says Goodling. "There's still money to be made if you can move your pregnancy rate above 20%." But Goodling does remind that, with anything, producers need to calculate the investment to obtain the goal of a higher pregnancy rate versus the economic advantage of achieving it.
Source: Purina Animal Nutrition LLC