Black Welsh Mountain sheep in North America are highly inbred. Our founding population was very small, so we do not have much variation from which to select. The USDA’s National Animal Germplasm Program performed a cluster analysis study on the population. This study looked at individual pedigree information and the population as a whole, then calculated how closely the sheep were related to each other. Then, those animals were sorted, and groups – or clusters – were made of individuals most closely related to each other.
Studies like this have shown that for some breeds – even those with numerous individuals – there may actually be very little genetic variation between them. Holstein cattle are one example. The population is enormous, but there are few strains or bloodlines within the population. Thus, the overall genetic diversity is low.
Within the Black Welsh Mountain breed, this study showed that there were eight main clusters (bloodlines) of sheep within the breed. Of these, Cluster Seven only existed within Canada, Cluster Two existed in a single flock on the east coast, Cluster Five was in one flock on the west coast, and Cluster Three existed in just two flocks on the west coast.
Within the breed, reading the cluster analysis tree from left to right, the clusters are related to each other in this order: 8, 6, 7, 3, 5, 4, 2, 1.
Clusters One and Two are more closely related than Clusters One and Eight, and so on. The three largest clusters in terms of national flock numbers are Clusters Four, Six, and Eight.
Here at Desert Weyr, we have been maintaining separate breeding groups of sheep in Clusters Four, Six, and Eight. We have also used rams in Clusters Two, Three, and One as line cross mates for our ewes.
We have noticed some differences between the clusters, both in general and at an individual level. Cluster Four is the most prolific. In our flock, the ewes that most often produce and raise triplets come from Cluster Four or a cross of Four and Six. Most of these ewes will twin, with a few singles and some triplets. Typically, live lambs per ewe bred for this group is 165% or more. This group also tends to have softer wool than the others. Their high production rate means these sheep need higher-quality forage, though they still should not need grain. Poor quality grasses will not allow them to express their full potential, and their softer wool is not quite as protective in harsh environments.
Cluster Six gives rise to great general-purpose sheep. Their wool type ranges from coarse to fine, and they are moderately meaty. They are not extreme in any characteristic. A few of these ewes will produce triplets, but most will twin with some singles. Typically, live lambs per ewe bred for this group are around 140-150%. These are good, solid sheep with the ability to perform in almost any environment.
Cluster Eight is full of woolly tanks. They are the heaviest and meatiest of our sheep. They are also the “hard men,” with long, coarser outer wool coats and thick manes. Their wool is almost always coarse, and they have the heaviest, thickest horns of all the clusters we’ve had. Many of these ewes are twinners, with the rest being singles. Typically, live lambs per ewe bred for this group hang around 140%. This cluster can produce a nice single or twin lamb on rough forages and will survive the harshest winters with little to no shelter.
This fall, with our continuing drought, we’ve decided to downsize our breeding flock by a third. Since we still wish to maintain separate clusters and continue our breeding program, we have elected to sell all of Cluster Four. These sheep are the most prolific, and they are more likely than the other clusters to produce triplets. This is not an advantage when our forages are of poorer quality, and the ewes get so far milked down that it’s hard for them to regain condition for the next set of lambs. This cluster will do well in a slightly softer environment with lush, nutritious forage that can support their extra lambs. Our altitude, harsh winter climate, and poorer forages make Cluster Eight (and to a lesser extent, Six) best for our farm.
All of our remaining Cluster Four and Four-Cross sheep, plus a selection from our other clusters, are now for sale. Check out our sale list to see what’s available. We’ll be adding lambs over the next few weeks as we finish evaluations.