The use of lower cost grazing systems for heifer development reports pregnancy rates for two year olds in a range of 77 to 100 percent. Because the actual number of 2-yr olds in the herd can be relatively small, one female can shift the percentage a fair amount. For example, one animal in 25 shifts the percentage by 4 percent. Never the less, the reproduction of these young females is critical to determining the fit of the management and environment to the heifers you’ve selected. While it is not valid to compare pregnancy rates from any particular study to females outside the study, it is useful to know the normal range in pregnancy rates in your herd and how they may match up with research reports.

During the past ten years, pregnancy rate for 2 year olds at the Ag Research Center at Hays has averaged 93% (see Figure 1). You will note several years where the pregnancy rate was in the upper 90 percent range. The test of whether pregnancy rates over 97% were economical would be in the feed costs and the unit cost of production (cost to produce a pound of weaned calf) for those years. The better question may be if the long term average of 93% is an economic level of reproduction.

With very few exceptions, any female that lost a calf went directly to the feedlot so the pregnancy rate represents females nursing a calf. This year’s 2-yr olds had 76% pregnant when examined with ultrasound 21 days after the bulls were removed.Calving: Two-Year Old Pregnancy Rates

This check was a week too early to confirm the status of all cows because the breeding project they were on required monitoring embryonic/fetal loss at this stage. At least half of the remaining 2-yr olds without an embryo are expected to be pregnant when they are rechecked as they come off pasture. The breeding season consisted of a single fixed timed AI on June 15 and natural service exposure from June 25 through July 31.

Pregnancy rates that are too high or too low can be expensive. Monitoring 2-yr old pregnancy rates and unit costs of production make excellent guides.