I am really pleased with my progress in improving my flock genetics using National Sheep Improvement Program (NSIP) data. I don’t think there is any way I could have made such fast gains by just picking sheep based on visual appraisal, or trying to sort through hundreds of data points in past records. (And, in fact, there is plenty of scientific evidence to back this up.)

The things I’ve been focusing on the most are lamb growth and maternal milk (maternal weaning weight, or MWWT). My growth numbers are starting to chase the system average, which is pretty cool, because a lot of people in the system feed grain to their lambs in the first 120 days, and I don’t.

Here is my weaning weight improvement compared to the averages for our breed:

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And post-weaning weight:

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Maternal milk is very important to me, since my lambs are born on pasture, and milk is the only input they have until they are old enough to digest grass. For people who offer their lambs high protein creep feed, this is less of an issue. As long as the lamb has genetics for growth, he can compensate for poor mother’s milk by eating more grain. My lambs can’t. So milk is critical; for me, lambs with poor milk supplies tend to linger here long past the age I’d like them to be ready to butcher.

I’ve been working hard to sell or cull ewes that have lower milk scores; though I’m doing it slowly. I also need mature ewes to stay here and produce butcher lambs, because I need those too. It’s a tradeoff of replacing highly productive (in number of lambs born) mature ewes with less productive yearlings that have better milk scores. My average score is improving, though it looks flat this year. This is mostly because I’ve brought in two rams which have very little data for MWWT, so they are pulling my scores back down. But overall, I’m pleased here: I’m seeing fewer “weanie” lambs which are held back by their mother’s lactation. And my keeper ewes are getting stronger and stronger in this score.

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One area where I’m diverging from the goals of many in the system is number of lambs born and weaned (NLB and NLW). These, naturally, are an encouraged focus; because it’s usually more profitable to get more lambs on the ground and to weaning, even if they grow slower. Grain feeders don’t mind this as much, because they can just accelerate the lambs’ growth with grain, when needed. But since that’s impractical (and expensive) for me, I’m generally very displeased with slow-growing lambs of any birth number. For me, it’s better to have twins that get out of here by November, than triplets I have to feed until Feb. So, I haven’t been focusing so much on NLB and NLW, and you can tell; there is a big gap between my averages and the national average. I’ve also actually dropped in NLB, which I think is attributed to something weird going on in my management system; and I’ve talked about that before. I’m going to continue to see if I can try to fix that, as I don’t think that’s purely genetic.

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The USA_HAIR index is a composite score, which combines WWT (the ewe’s own genetics for growth as a lamb), MWWT (the ewe’s maternal milk, plus any other maternal factors which figure in to encouraging lamb growth), NLW (number of lambs weaned); and negatively weights NLB. The last thing is somewhat counter-intuitive, but Dr. Notter’s explanation clarifies: “Small negative emphasis on Number of Lambs Born EBV favors ewes that wean large litters without losing any lambs. A ewe that produces twins and weans them both will thus be favored over a ewe that has triplets but weans only two lambs. However, ewes that wean triplets will always have substantially higher index values than ewes that wean twins.”

I am making modest gains on this index, but not compared to everyone else, because it weights NLW heavily, and most people in the system seem to be focusing on that.

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I am finding that I don’t always “agree” with this index, because it does not weigh growth or maternal milk heavily enough for what I need. I prefer the “Maternal$” index, which seems to weigh more heavily growth and milk, which makes more sense for grass-fed or “range” flocks. When I want to do a “quick sort” on which sheep I think are the best for long-term breeding goals, I tend to use Maternal$ to make my top and bottom picks.

Here is the “dashboard” of my top ewe, whom I think is pure bliss as far as data goes. It doesn’t hurt that she’s also quite attractive in appearance; but I wouldn’t care if she looked like a hippopotamus. She has very profitable genetics! I can’t wait to get some sires out of her. Annoyingly, this year, she had twin ewelambs, and she had them about 30 days late, which means I don’t know the sire. But they are fabulous growers already. So some lucky somebody is going to get some really awesome, modestly-priced commercial ewes this summer!

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