Identifying Reproduction Benchmarks

Published on Wed, 03/21/2018 - 11:17am

 Identifying Reproduction Benchmarks

 By Jaclyn Krymowski for American Dairymen

 Among the most important assets a cow can provide to a farm is pregnancy. The value of a single pregnancy varies from farm to farm and has a host of contributing factors. It’s estimated at an average worth anywhere from $250 to over $500, depending on the markets and specific operation. Every day a cow is kept open past an established voluntary waiting period (VWP) her expense increases.

The benchmarks a herd should aim for needs to be evaluated in a team effort involving farm owners and managers, veterinarians, and everyone involved in the breeding process. A handful of key reproduction analysis measures can be narrowed down to improve pregnancy success.

Where to look
The big analyses to watch include pregnancy rate (PR), and conception rate (CR) in both cows and heifers. Daughter pregnancy rate (DPR) is another measure of note is of ever increasing importance in many herds. To get an idea of where your farm stands on each of these measures, it is a good practice to review the national and state breed-specific herd averages and understand what factors contribute to each.
Pregnancy rate is determined either by the number of animals pregnant divided by the total number of animals eligible for pregnancy within a specific time frame – usually each 21-day cycle – throughout the year. Another way this is calculated is by a herd’s total CR multiplied by the heat detection rate (HDR) or service rate (SR). “Eligible” cows or heifers refers to any animal that is open past the established VWP and not marked as a “do not breed” animal. According to AgSource Dairy, the annual 2017 PR herd average out of 2509 Wisconsin Holstein herds was 18.1%. Herds in the 80th percentile were as high as 25% for mature cows. Jersey PR statistics were 21% for cows from 127 herds in the state; the 80th percentile was a 28%. Comparatively, heifer conception rates were 59.7% on average with the 80th percentile being 67%.
Conception rate is calculated by the number of confirmed pregnant animals by the total number of inseminations. According to the Council on Dairy Cattle Breeding (CDCB) the most recent national average from December 2017, calculated from over 200,000 Holstein cows born in 2015, is 59.7%. The calculation for Holstein heifer CR born in 2016 is 68.7%. For Jersey cows and heifers, the CR is 54.7% and 64.3% taken out from over 300,000 and 400,000 animals respectively. For a local comparison, the AgSource Wisconsin Holsteins herds averaged around the 57.5% with the 80th percentile being 64% for first lactation groups. Heifers averaged around a 60% CR with the 80th percentile being over 66%. The state Jersey herds averaged 63% in the first lactation and the upper percentile herds being as high as 75%. Heifers averaged at 59.7% and as a high as 67%.

Many of the factors impacting CR and PR are directly linked to the breeding process, namely, these include fertility of the cow and semen used, time of insemination, and skill of the technician. Both analyses are highly accurate to get an idea of where a herd is standing because they draw their data from confirmed pregnancies. However, they require diligent record keeping and all services need to be recorded. Likewise, these benchmarks don’t account for all fertility data. For example, only animals that are presented for A.I. are accounted for, pregnancy rates can be high, but fertility can be low because too few animals are being presented for service.

Other considerations
Heat detection rate, like the PR equation, is the number of animals bred divided by the number of animals eligible for breeding, typically each 21-day cycle. This measurement is perhaps the greatest impacted by management strategy. Without regular monitoring and recording, a herd with a poor HDR percentage can be difficult to pinpoint if heats are not being observed or animals are failing to cycle at all. For farms that don’t use a form of electronic monitors to track heat detection, the service rate is typically used to measure HDR. Service rate is the proportion of cows eligible for service in a set period (again usually every 21-day period) that are bred. The minimum service or heat detection rate is usually suggested to be at least 60% but well-managed farms can be well above.
In recent years there has been more emphasis on sires with higher DPR to genetically improve overall fertility. The DPR calculation currently used deviates slightly from the PR formula, as it is more technically accurate. The national Holstein cow averages from the CDCB was 36.2% taken from over 300,000 individual animals born in 2015. For Jerseys born in the same year, it was 38.1% out of over 50,000 individuals.
For herds on DHI test, the PR, CR, and HDR report can be found on the DHI-202 Herd Summary for each test period and the last 12 months. In PCDART report 126-Pregnancy Rate Summary will calculate PR according to 21-day intervals or days in milk, the CR and HDR can be found on report 801.