Heifer Growth Applet^™ Overview

Load Heifer Growth Applet™

Teaching a class on dairy heifers? Apply for free coupons (for educational use).

Heifer Growth Applet^™ makes it quick and easy to analyze the growth of a group of heifers, by comparing their height and weight to established standards with respect to age. The program runs inside a standard web browser, and remains functional even if the Internet connection is lost (except that data cannot be uploaded or downloaded without an active Internet connection). It is quite simple to use, so you may want to just jump in and give it a try.

 

There are three major areas. At the top is a Chart and Display Area which shows the growth chart, or another panel selected by clicking on one of the other panel buttons. There is a horizontal line of three Panel Buttons. Each button shows a different display in the area above, like flipping the pages of a book. The Data Entry area is at the bottom. There are also buttons to Log in or Load data from the server, Save Data to the server, and Add or Clear data points.

Data Entry: Data sets can be downloaded, or by typing data into the area underneath the chart. Points are drawn for you on the chart when you click the "Add Point" button".

The Growth Chart plots the points you enter on a background growth model. The default model shows "Penn State" growth standards which are averages collected from Holstein heifers in 1997 by Heinrich and Losinger, showing mean (the midline), and plus or minus one standard deviation (the shaded area), for height and weight. You may choose other growth models if you like.

Here we have plotted growth targets from Pat Hoffman (the dots) on top of the Penn State standards. Note that each heifer gets two dots, a blue one for height and a red one for weight. If you click on a dot, a black line is drawn between the pair of dots, and corresponding numbers are shown in the data panel. You can change many display options (such as units for weight and height) by using the Setup panel.

The Statistics page (shown by clicking the Panel Button "Statistics") calculates descriptive statistics including mean and standard deviation for a group of heifers. Each statistic is calculated on the raw data, then again on transformed data, i.e. the vertical distance between each point and either the midline or the shaded zone of a model.

.

Finally, the Setup page (shown by clicking the Panel Button "Setup") allows customization of everything from measurement units to the growth models themselves. It may be easier to enter data in one format, then switch to another for viewing the results For example, you can use a carpenters tape to measure heartgirth in inches (rather than weight), set the weight entry format to "heartgirth", then switch back to pounds or kilograms to view the results. It is also often easier to enter birthdates, and have the exact ages of heifers, than to do a rough estimate of age.

Load Heifer Growth Applet™ (in another window)