Which Sheep to Keep?

Heading to the corrals on weaning day.

Every year about this time, we wean our lambs. Part of this process involves evaluating the ewes - we try not to spend more resources (time, money, and forage) on ewes that need to leave the flock (which can be necessary for a variety of reasons). Part of this process is also selecting the ewe lambs that will replace these ewes. This year, however, is more complicated; this year, we’re downsizing our flock due to a loss of fall grazing opportunities and my partner Roger’s desire to step back from the day-to-day responsibilities of raising sheep. This year, we’re selecting the ewes that will be the basis of our flock moving forward.

This process always starts with our long-term breeding objectives. I like to think about the ideal ewe for our flock - knowing that this ideal is always a direction rather than an end point. For us, we want a moderately-sized ewe who can thrive on a wide variety of forages. A ewe that doesn’t need to be coddled - hardiness and longevity are key traits in our operation. She needs to be resistant to foot rot and internal parasites. We want a ewe that will conceive twins and that can count to two once her lambs are born. She needs to be able to lamb without help, on pasture, and produce enough milk from what she can graze during the springtime. She needs to bring in both lambs at weaning - and wean close to her weight in lambs in 100-120 days. She needs to respect our electric fences. In other words, she needs to be adapted to our system and our environment.

A sheep breeder from Australia recently introduced me to a different way of looking at all of this. In his mind, we can either look at the entire flock or manage individual animals. While we do look at the whole (the flock), I realized during our conversation last week that we make decisions based on individuals - how many of the traits I described in the preceding paragraph does THIS particular ewe exhibit? And how likely is she to pass those traits on to her lambs? Our entire record-keeping system is designed around this individual animal analysis.

At weaning time, I usually combine the information I record at lambing on ease of birth, mothering ability, and lamb vigor (which we score objectively) with a visual appraisal of each ewe lamb. If mom excels in these maternal traits, we have some confidence that daughter will as well. But she can’t be a dink - she has to have thrived in our environment and on our forage. And she can’t be crazy, either - a pretty ewe lamb who won’t stay in the electric fence isn’t so pretty!

This year’s evaluation went beyond looking for replacement ewe lambs, though - we needed to figure out which of our “running age” ewes we’d keep. In addition to our normal culling criteria (missing teeth or a lumpy udder), I decided to look at four factors:

• The ewe’s most recent EZ Care score (which measures the maternal traits outlined above). A perfect score is 3, but we’ll typically keep a ewe who scored 2 (which usually means I had to help her lamb).

• Whether we had to treat the ewe for internal parasites during the last year (and how many times).

• How much younger (or older) than the average age of our ewes is she?

• How many pounds of lamb did she wean, on average, over the last two years?

My next step will be to actually look at all of the ewes I’ve decided to keep on paper - mere numbers can’t replace what my friend Ryan Mahoney calls the “eye of the shepherd.” I’ll look for structural correctness, body condition, and other physical manifestations of quality breeding. And I’ll take another look at the ewes that I’ve decided (again, on paper) to sell.

Even with all of this analysis, I had the realization while I was selecting replacement ewe lambs last weekend that one of the results of sticking with our breeding program for these last 16 years is that I can trust our genetics. The ewe lambs I marked as potential replacements at birth are a uniform bunch - as are the ewe lambs I marked as sale lambs. By maintaining our core breeding generations over 16 generations of sheep, I feel like we now have sheep that are genetically and phenotypically adapted to our environment and our management system. I’m happy with the ewes and lambs we’re keeping; I’m sad to see the ones we’re selling leave. But I’m also happy knowing that our ewe and lamb buyers will be getting quality sheep!