Penn State Dairy Herd Metrics
Today's higher feed costs impact not only the lactating herd, but the replacements being raised as well. This increased investment cost for replacement animals has producers examining their heifer inventories and replacement needs. There are several key metrics that are used to determine each of these heifer related needs, and are the basis of the Penn State Dairy Herd Metrics application.
Knowing how many replacements you need and produce annually to achieve your dairy's goals (maintain herd size, expand, or downsize) is a key to managing heifer inventories. These numbers are easy to calculate with a few key herd metrics: herd size (HS; milking and dry cows), average age at first calving (AFC), herd cull rate (CR), calving interval (CI), calf sex ratio (SR), calf mortality rate (CM), and the non-completion rate of heifers (NCR; heifers that enter the replacement growing business but do not enter the dairy herd). The formula to estimate the number of heifers needed annually is:
HS x (AFC ÷ 24) x CR x (1 + NCR)
The formula to estimate the number of heifers produced annually is:
HS x 12 ÷ CI x SR x (1 - CM) x 24 ÷ AFC
Both calculations rely on accurate estimates of the key herd metrics.
Dairy Herd Metrics App
To assist producers and consultants with determining these values, the Penn State Extension Dairy Team developed a mobile app and website called Penn State Dairy Herd Metrics App. This site is accessible from any Windows, Android, or Apple computer, tablet, or smartphone with an internet connection. The app has four basic sections: data entry, inventory graph, saved scenarios, and assessing economics. Each section provides a unique opportunity to evaluate an individual herd's current position and the possibilities that may be achievable. The site uses the same login for existing users of the DairyCents , DairyCents Pro , or CropCents apps, or a new user account may be registered for free. The login is needed to store and retrieve potential scenarios.
Logging into the app, users have the option to enter data or retrieve a stored scenario. Data entry takes the user to the page to enter the seven key herd metrics listed above. For assistance in determining these metrics, visit the how to video at the bottom of the page for assistance in finding reliable sources of data for the herd metrics.
Once the metrics are entered, click on the calculate button to determine the annual number of heifers needed and the annual number of heifers produced. Once calculated, the user may adjust an individual metric and click calculate to readjust the entries. The user will now have the option to graph the entered data in the herd metric diagram, test other scenarios, or assess economics of the heifer inventories.
For further information on heifer nutrition, health, and economics, be sure to visit the Penn State Extension Dairy Team pages for Calves and Heifers.
The graph feature displays the entered metrics and their impact on the heifer system and the lactating herd. It is meant to express where potential management limitations or bottlenecks exist. It is only available to the original data entered.
Users have the option to create and save scenarios within their accounts. This allows for a comparison of potential "what-if" options to the original metrics of the herd. Selecting create a scenario will create a copy of the current data in a second column. The user then can adjust any and all metrics and see its impact on the annual heifer needs and production. This is a great feature to see what might need to happen to achieve a herd's heifer goals.
The final section of the app is the assessing economics feature. Users will need to enter an achievable or current price per head for culled cow sales for beef, cull cow sales for dairy, and price of replacement heifers. After entering this information and selecting to calculate results, the app will determine the annual gross amount possible if all culled cows went to beef and the annual gross amount if all cull cows went for dairy. This is based on the original cull rate entered and not a scenario cull rate. The app will then determine the potential gross profit if the number of heifers produced exceeds the number of heifers needed, or the potential cost to maintain herd size if the number of heifers produced does not achieve the rate at which heifers are needed. These values are reliant on both accuracy of the prices entered and the herd metrics entered, and merely show the potential to an operation and not actual revenues.
Controlling costs is just as important as ensuring the quality and quantity of heifers entering the dairy herd. Understanding a herd's unique heifer needs and availability based on key herd metrics can achieve insight into potential limitations or excess availability of heifers. Controlling these metrics to improve access to replacement opens the dairy business to greater control of quality of heifers becoming their next lactating herd participants.
J. Craig Williams