In this neck of the woods, there is nothing better than having coffee shop bragging rights. However, in many cases those bragging rights leave out a few important details. These details are often overlooked, and while it is not intentional, knowing the difference between conception rate and pregnancy rate, will make or break many producers’ coffee shop bragging rights. In addition, when producers sit down to figure out if they will use a straight Time AI (TAI) synchronization protocol (7-day CO-Synch+CIDR) or include heat detection (Select Synch), or to calculate the success of their breeding season at its conclusion, it is key to make sure that apples are being compared to apples.
Three key calculations should be taking into account:
- Synchronization Rate (%): The percentage of females detected in estrus compared to the total number of cattle synchronized.
- Conception Rate (%): The percentage of pregnant females compared to the number of females inseminated.
- Pregnancy Rate (%): The percentage of pregnant females compared to the total number synchronized.
Many people will just look at the overall pregnancy rate, however when evaluating the amount of labor and resources to the number of pregnancies achieved, all factors should be included. In addition, using conception rates as an indicator of the overall success can be misleading. Conception rate does not take into account the number of females that were not inseminated.
For example, if in herd A 100 head of cattle were synchronized for breeding using the Select Synch Protocol, 50 of them were detected in heat and inseminated, resulting in 70% of those females becoming pregnant.
Table 1: Comparison of TAI vs. heat detection
| Herd A | Herd B | |
| Synchronization Rate | 50% | - |
| Conception Rate | 70% | 55% |
| Pregnancy Rate | 35% | 55% |
* Because herd B was a TAI herd there is no synchronization rate.
In herd B, 100 head were also synchronized using the 7-day CO-Synch + CIDR Protocol and bred, however this herd was bred with a straight TAI that resulted in 55% of the females becoming pregnant.
In using herd A and herd B as an example, at first look, it seems as though herd A had the most successful AI breeding season, but often times producers fail to take into account the number of females that are not bred using TAI into their overall evaluation. In this case, while herd A had much higher conception rates, the 50 head that were not inseminated were not taken into account. Thus, taking all factors into account, and evaluating these two herds based on pregnancy rates, which include all females, shows that actually herd B had a greater AI success.
Taking all three factors into consideration will help producers best manage their breeding season. In addition when choosing an AI Protocol for their herd, producers need to consider the females that will not be exposed to AI breeding if TAI is not utilized.
For more information, contact SDSU Extension Cow/Calf Field SpecialistKalyn Waters at the Winner Regional Extension Center at (605) 842-1267 or contact any SDSU Extension Cow/Calf Field Specialist or Beef Extension Specialist.
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