One of the most intriguing aspects of breeding animals, to me, is breed type. In simple terms, type refers to phenotype, or the outward manifestation of traits which tell your eye, this is a Katahdin Sheep versus this is a Romney. For people who show animals, part of the preoccupation with type is just emphasis on “purebred-ness.” An animal that lacks type is of questionable pedigree, or an indicator of undesirable genetic drift from the norm for that breed.

imageBut if we don’t compete in shows, why would we care about type in working, performance or production animals? Well, for one, we want to stick to the observable physical traits which are the goal of the breed; whether it be fine wool production or deep loin eye. If you look at historical illustrations of meat-type livestock, they often look like the above engraving: corpulent bodies, tiny legs and head. These were exaggerations, intended to emphasize the traits they most wanted in breeding: good muscling, high capacity for forage intake, thriftiness, and high wool production. The facial appearance and leg length were don’t-cares, so they barely illustrated them. Our old #33, now nine years old, would not win a beauty contest, but she often reminds me of these old-fashioned photos: all body, no legs and neck!

Big Barrels of Grass

Practically speaking, for observable traits, a top priority in Katahdin ewes for grass-fed systems is the ability to digest a lot of grass. Though good green grass is high in protein (which equates to growth), it’s also full of water. So we need meat sheep to be able to take in vast quantities of forage. Lactating ewes turn this grass into rich milk, and growing lambs turn this grass into muscling and fat.

What’s interesting about a lot of modern sheep breeds in our country, however, is that they’ve been primarily raised on high quality hay and grain for many generations. Hay is dry, and has give up most of its water content, so it’s more nutrient-dense than fresh grass. Grain is denser still. Sheep fed on these inputs do not need to take in as much volume as pastured sheep. So many sheep breeds have diverged away from the historical corpulent, big-barrel-of-grass appearance to a more streamlined, leggy and slim animal. “Tube  shaped” is what many people call them, and the most extreme examples seem to turn up in American show Suffolks. A tour of Google images gives a great summary:

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These tube sheep seem optimized for utilization of cheap grain produced in the Midwest; they don’t need a lot of stomach capacity, and they probably have a high tolerance to the acidity in the rumen that comes with a low-roughage feeding schedule. But they often do poorly when put on grass, probably because they can’t take in enough forage to grow well. It’s not to say that these are bad sheep, we just have to keep in mind their purpose; different management systems with different resource availability require very different animals for ideal performance.

Comparing the Suffolk pictures to the Katahdin ewes can make the Katahdins appear fat. But all these ewes are currently at a body score condition of about 3 to 3.5 (as judged by feeling the fat cover near their hip bones); so they are neither over- or underweight. They just have very large abdominal capacities full of low-protein grass hay.

Throwbacks

The Katahdin breed association encourages cross-breeding; they allow us to register crossbreds and “upgrade” them over time back to purebred status. The upside of this is hybrid vigor: we are continually introducing fresh blood into the gene pool. This can also allow us to bring in new genes which advance the breed in the traits we want to improve. The  downside is some continual degradation of breed type. We can get “throwbacks” that are pulling undesirable traits from some generations-ago ancestor, creating puzzling outcomes from what seems like a good pairing of two very typical Katahdins.

One interesting dice roll I’ve been getting is from the cross between my Montana ewes and some old-time Washingtonian genetics. They are sometimes (not always) very Suffolk-ey, more tube-shaped animals that look like nothing else in their pedigree. That’s the funny thing about outcrossing, is that you often get something that doesn’t resemble either parent. The girl above is still a good ewe, but you can see that long-leggedness, and just not as much body capacity as the rest of my ewes, even though she is in adequate condition. Even her facial expression and dark-point coloration resembles a Suffolk.

These twin sisters born this year look a little like thoroughbred race horses to me.

See the resemblance? Winking smile

Thoroughbred horse

The difference between them and more Katahdin-ey ewes in the same age group is subtle, but clear. The one on the left, has a dromedary appearance, less muscling on the rump, and less filling out her stomach. The one on the right is more Hereford cow-like, with a big square butt end, short legs, and a fuller capacity in her rumen. They are opposites: all legs, no body; and all body, no legs!

Another comparison, this one shows how the one on the left has inherited something show people like: heavy bone in the legs, to go with the willowy body. The one on the right has more standard bone density, and a more barrel-ey abdomen.

And here is the other racehorse, walking along with some much fuller-capacity mature ewes; I think the tube-versus-barrel shapes are very evident here:

Bell Curve Boundaries

But notice, these three runway model ladies are still here! Despite my not preferring this aspect of their type, they are still good ewes with solid NSIP metrics as compared to my total spread. They beat out other ewes in getting to stay. And that’s because everything is a bell curve: we want general consistency in our flocks, but we also want to have some tolerance for variation from the mean. Just like in my rams, there is a spread of size and performance; and depending on pairings, they may produce progeny like themselves, or better or worse. We want to try to stay in the middle on many traits, but accept that we’ll have some outliers that fall on both ends of the curve.

On the other end of the spectrum from the two racehorses and the Suffolk-ey ewe is their auntie, above, who carries so much condition, her fat undulates with every stride. This does not thrill me either, as I suspect the cost to maintain her blubber over the winter is greater than the more modestly conditioned ewe behind her. But there again, it’s ok to have some variation, and daughters of all these ewes will vary yet again as different sires are introduced. These traits are just a few of many for which I select, others being mothering ability, milk production, birthing ease, birthweight, temperament, shedding coat and pounds-per-ewe-weaned. I’ll breed the racehorses to something stockier, and make sure that Ms. Blubber is paired with a trim fellow, and hope that subsequent generations continue to converge upon the ideal goals for which we all strive.

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