Analyzing Linear Appraisal Data

Congratulations! You made it through Linear Appraisal. That's a huge step towards herd improvement. However, to get the most impact out of the data, it helps to be able to interpret the numbers. In this blog I'm going to share a few things that I've learned through trial and error, button pushing, and conversations with colleagues. My first bit of feedback is to slow down and take a deep breath. LA is notoriously overwhelming. It's normal to have strong reactions afterwards. You've put a lot of money, time, and passion into this project. If you hadn't you wouldn't be participating in ADGA's performance programs. Now that you've taken that deep breath, let's do some reality checks using Leia as an example. BTW, Leia was indeed named in honor of Carrie Fisher. 

The first tool that I like to use is "Linear Trait Trends," found under the "Type" pull-down menu in ADGA Genetics (adgagenetics.org).  That will take you to a pull-down menu where you can select the linear traits that you are interested in analyzing. I'm going to select "rump angle," since rumps are a hot topic in the Nigerian community. That gets me a lovely little color coded table showing trends for rump angles over the last sixteen years. 

Leia's rump angle is 32. Looking at the chart values for 2019, Leia is over +1 standard deviation from the mean. Cool. 

The next tool that I'm going to look at is the rump angle diagram from the ADGA Linear Traits handout that I received during LA. The order in which you look at these items doesn't matter. All that matters is that you take the time to look at them. :)

Leia falls in the range between 25 and 45, with 45 being an undesirable extreme. This brings me to the next bit of helpful information, gleaned from a colleague.

According to my colleague's appraiser, the ideal range for rump angle is 30-40, with 35 being the "best" score. I'm feeling pretty good about Leia's 32! 

Cautionary note 1: Keep in mind developmental stages! LA scores are measured against an ideal MATURE goat. Nigerians take about three years to reach maturity. Don't expect ideal scores from a yearling or a first freshener. Also, don't expect strong rump scores from newly fresh does. It takes time for them to recover.

Cautionary note 2: As I keep hearing from breeders with FAR more experience than my 10 (or so) years, keep in mind the WHOLE goat. Don't get hung up on one piece of the puzzle. Step back and look at the whole goat when making your decisions, especially when thinking about culling. This includes not just linear data, but what you know about your animal's genetics overall. 

For example, Leia isn't perfect. She had a single buckling in 2019 and didn't get the udder capacity that I had hoped for as a second freshener. However, I know her genetics and I know that her milk will come. I'm taking the long view with this doe, especially since I know that she is from slow-to-develop bloodlines. 

From the ADGA - Linear Traits handout given during LA.

Here are the ranges reported by my colleague. Keep in mind that it's not firsthand from her appraiser. Moreover, other appraisers may have different opinions. However, these numbers make sense to me, which makes them worth sharing here. :)

• Strength: 24-34
• Dairyness: 30-35
• Rump Angle: 30-40 (35=best)
• Rump Width: the wider the better
• Rear Leg SV: 20-30 (25=best)
• Fore Udder: 30-45
• Rear Udder Height: 30-45
• Rear Udder Arch: 25-35
• Medial Suspensory Ligament: 20-30
• Udder Depth: 25 and up, varies by age
• Teat Placement: 15-35 (25=best)
• Teat Diameter: 15-30 (25=best)
• Rear Udder SV: 25-30 (no more than 35)