Monitor your herd’s pregnancy rate

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Editor’s note: The following article was written by Kathy Lee, Michigan State University extension dairy educator.

Pregnancy Rate (PR) is a key performance indicator for reproductive performance in dairy herds. It is defined as the percentage of cows eligible to become pregnant that actually do become pregnant in a given time period. PR is dependent on the percentage of inseminations that result in a pregnancy and heat detection rate (or insemination submission rate for herds with timed AI programs). It is important to identify which cows are in heat and then successfully breed them.  For herds that use timed insemination programs, level of compliance to the synchronization protocol will affect PR.

Pregnancy Rate generally is calculated for 21-day periods. However, it can be reported for other time periods. For DHI herds, Dairy Records Management Services (DRMS) reports PR on the DHI-202 Herd Summary for each test period (typically based on one test per month) and for the most recent 12 months. Report 126-Pregnancy Rate Summary in PCDART (herd management software from DRMS) calculates PR for 21-day intervals relative to calendar date or days in milk.

Cows are considered eligible for pregnancy or breeding if they are open, past the voluntary waiting period (VWP) and are not designated as Do Not Breed (repro code C). DRMS allows VWPs to be reported for two groups of cows: first lactation cows, and second and greater lactation cows. VWPs should be reviewed periodically and updated as needed. When the actual VWP is longer than the reported VWP, Pregnancy Rate will be underestimated. The reverse is true when VWP is actually shorter than the value reported through DHI.

All reproduction management events, such as breeding dates and results of pregnancy diagnoses, should be reported. Completeness and accuracy of data will ensure valid PR calculations. Cows no longer in the breeding herd should be coded appropriately.

Dairy Metrics benchmarking system, available through DRMS, was used to obtain information about DHI herds in Michigan. The average Pregnancy Rate for Michigan herds as of May 25 was 17 percent with a standard deviation of 5.6 percent. Consequently, approximately two-thirds of the herds had a PR between 11.4 and 22.6 percent.

Herds with a PR of 22 percent or greater were summarized to compare to all DHI herds in Michigan. The following table lists averages for several characteristics for these two groups of herds.

 

Trait

All DHI Herds

DHI Herds > 22% PR

Number of Cows

280

631

Rolling Herd Average Milk (lb)

22,762

25,345

Days Open

156

121

Days to 1st Service

93

76

Conception Rate (1st service)  %

43

43

Heat Observed/Submission Rate %

43

61

Herds with PR at 22 percent or greater tend to have higher milk production, fewer days to first service, less days open and higher percentage of heats observed or submission rates. The conception rate for first services was the same for both groups (43 percent).

Pregnancy Rate is an excellent tool for monitoring dairy herd reproductive performance. Dairy herd owners and managers should work with their management teams to set appropriate goals for their herds.



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Jim    
NC  |  June, 06, 2011 at 07:10 PM

Hi, Nice article, DRMS is reallyl Dairy Records Management Systems. http://www.drms.org/


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