Sheep selection should start with performance and then a visual evaluation.
There are a number of tools available for selection, but the key is to combine operation goals with production benchmarks and visual appraisal to select the best sheep for your farm. Plus, producers should take a look at an often overlooked part of the selection process: culling strategies.
Not all sheep are created equal and not all farms are created equal. Before you even walk out to the barn to look at the sheep, the first thing you should do is define your market. Who are you selling to and what does your customer want? You will then be able to define what characteristics are important for your ewe flock to exhibit. Then, step two is to evaluate current characteristics exhibited by your ewes and decide what traits need improved upon. You might take out a tablet and a pencil and write down what you feel are the 5 most important characteristics of your ideal ewe. Compare that to what is most important to your customer.
Does your operation have any goals and production benchmarks? What type of selection principles do you need to employ in order to reach those goals? Where are you at currently with production and how do you reach your benchmarks? After you answer those questions, add one more question into the mix. Do you remember the typical job interview question "where do you want to be in 10 years?" This is a good time to sit down and think about what your sheep and your sheep operation should look like 10 years from now.
Let's take a look at an example flock. This flock produces lambs for breeding stock. Buyers are looking for moderate sized sheep with good muscling, structural correctness and the ability to perform well on pasture. The producer also wants to increase the lambing percentage so there are more lambs to sell. So, where does this producer start when selecting replacement ewes and rams to breed to the flock?
When the sheep are lambing, the producer should be tracking data such as birth weight, birth type and weaning weight. The producer can also record body condition scores at certain times throughout the year to assess a ewe's ability to maintain body condition on pasture. Because the buyers want heavy muscling, the producer can use ultrasound scanning to assess loin eye size and backfat thickness. Lighter muscled animals that don't meet a minimum production benchmark can be sent to the sale barn. The data collected by the scanner is also useful as a marketing tool to show buyers the amount of muscling in the animals. All the performance data mentioned so far can also be evaluated through NSIP/Lambplan to develop genetic breeding values that are a more accurate measure of performance.
Because the producer wants to increase lambing percentage, he or she may focus on selecting replacements that were born as twins. But, the producer also needs to be aware of other factors that affect twinning besides genetics. Nutrition is a very important part of the equation, so evaluation of feeds and feed quality will be important.
The last step is for the producer to visually appraise the animals for structural correctness: level top, level dock, correct set to legs, strong pasterns. You might also consider body capacity and muscle shape and design. Short hipped, round muscled animals tend to walk with a short stride and can have problems at lambing time. If your sheep have many hills in their pasture, freedom of movement can be very important. Purebred Dorsets should also exhibit certain breed characteristics. Refer to the breed standards for more information on what a Dorset should look like.
Once the sheep has passed all these selection parameters it is now ready for marketing. Thank about what characteristics of your sheep and farm set you apart from others so that your customer prefers what you produce? Focus on those characteristics in your marketing efforts.
Let's throw in a couple points on culling strategies. If there are families of ewes within your flock who never produce twins, perhaps it is time for them to hit the road. Young ewes will often produce just one lamb in their first pregnancy. However, they should have the ability to produce twins once they are more mature. Or is there some other reason why this ewe doesn't produce twins? Is she normally too thin? Is she prone to internal parasites? A yes answer to either of these questions is certainly reason to cull this ewe and remove her genetics from the flock.
Sheep selection is an important part of building the genetics in your flock to meet your production goals. Set some production benchmarks that you want to achieve this year, in two years and even ten years down the road.