If you’ve been hanging around our website for a while or have been in the process of researching Katahdin sheep to purchase, then you’ve probably run across acronyms like NSIP, or EBV’s. NSIP stands for the National Sheep Improvement Program. EBV’s are estimated breeding values. We have alluded to them being valuable tools for selecting genetics to improve you sheep flock on several occasions. So today we are going to take a few minutes to clarify what they are, how you can use them, and where you can find more resources if you are interested in learning more.
The goal of NISP is to do exactly what the name states. Their goal is to use performance based data to provide information to producers to help them to maximize their flock’s performance and profit. The way they do this is by collecting all sorts of data from thousands of sheep raised by different producers all over the country. This data is put into a complicated database where EBV’s for individual animals are produced.
EBV’s aren’t static. They can and will change as new data and new animals are added to the database. They also come with an accuracy rating. The more relatives a sheep has recorded, the more accurate the EBV’s are expected to be. A given animal is essentially ranked based on how it performs as compared to the other animals in the database.
While the EBV’s are estimates, you can learn more about the potential of an animal from this data than you can by looking at them standing out in a field.
This is particularly true for rams since you can’t see how much milk he produces or if he’s a good mother. It has been proven that by using performance based data rather than visual appearance you can make genetic gains faster.
We humans have a tendency to be attracted to the biggest fattest looking lamb out in the field. Unfortunately, while this one might look amazing, it is rarely the best performing lamb in the flock. This lamb is usually a single born from a slacker mother. By selecting the biggest nicest looking lamb, you might actually be selecting against important traits like prolificacy and ewe efficiency. EBV data helps us avoid these biases.
Note, we are going to be referring to Katahdins throughout this article as that is what we breed. Katahdin breeders have relied heavily on EBV’s. They have made remarkable performance advances as a result. However, NSIP is not Katahdin specific. It has databases for a variety of sheep breeds, so be sure to check if your breed participates.
Data is collected on a whole slew of different performance traits.
Data collected ranges from things like birth weight and number of lambs born to fecal egg count scores to carcass and wool qualities. A complete list of the traits and descriptions can be found on the NSIP website. Each animal is assigned a score for each and every one of those traits. They are also assigned an overall score. This score is the hair index for Katahdins. A sheep with a very high hair index is a very good overall sheep.
Depending on your breeding goals you can select stock that has high scores for individual traits you wish to improve or just select for a high hair index. If there happens to be a trait your flock is very deficient in, it can be highly advantageous to select for a ram with a very high score in that trait. If you are generally satisfied with flock performance and have no traits you’re desperate to improve you might opt to select a high hair index ram. Not sure what your breeding goals are? You can refer back to our article on selecting breeding stock for some basic guidelines.
EBV’s offer a wealth of information.
The image above is a screen shot of example EBV’s from a ewe we recently purchased. You can see her US Hair Index is above the 90th percentile. She is a very good overall sheep, and would generally be an excellent choice. BUT, no sheep is perfect or the right answer to every problem. Even with a hair index that high she still scored in the 5th percentile for weaning fecal egg count (WFEC), and below average for birth weight (BWT) and post weaning fecal egg count (PFEC). If your flock desperately needed better parasite resistance, she would be a bad choice.
EBV’s are a tool.
Keep this in mind as you learn. Everyone uses this data a little differently. There is no right or wrong thing to select for. It is all dependent upon your flock and your goals. That being said, generally speaking you’d want to purchase stock that is better than average at most or all the traits. You don’t want to be using a ram that performs more poorly than the breed average. Otherwise, he will not be improving your flock like he should be.
You can determine how a given sheep compares to the average by comparing its score for a given trait to the percentile reports. A sheep with a trait that scores less than the 50th percentile is performing worse than average for that trait. Keep in mind though that there is no such thing as a perfect sheep, and you can’t improve everything all at once. Focus on selecting for a high score in what you deem the most important traits while minimizing loss in other traits.
EBV’s are a lot of data to try to wrap your head around. The NSIP website has a variety of excellent information on how to use their data effectively. If you are interested in employing EBV’s in your flock, we would encourage you to dig into the system in more depth as this is outside the scope of this article.
Next time we are going to be discussion how to select a Katahdin for milking, so don’t forget to sign up for our newsletter to have that delivered directly to your inbox!
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