National Sheep Improvement Program – NSIP

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I am the only St. Croix Hair Sheep breeder enrolled in and submitting data to the National Sheep Improvement Program – NSIP. NSIP calculates Estimated Breeding Values (EBVs) for each sheep based on the performance of that sheep and its relatives. I ask serious breeders to consider joining this program with me for the breed’s good. Please keep reading for a special offer to anyone who buys my stock.

Many producers talk about the importance of selective breeding based on performance, but rely on their eyes or a spreadsheet. While that’s a great start, the EBVs you get from NSIP can tell you the rest of the story. This is because one animal’s performance influences not only his own EBVs, but the EBVs of his dam, sire, siblings, progeny, and other relatives also change with his, and vice versa. “Estimated Breeding Values are numbers that reflect the inherited genetic potential of an animal as expressed in future generations” (source).

My NSIP Data

Please look at the SheepGenetics report I received through this program last July. This report is based on data I gathered from all my lambs for the last 2 years. That includes weights at birth, 60 and 90 days, litter size, rearing type, and fecal egg counts at 90 and 120 days. You will notice there are lots of headings, with EBV ratings below them. The EBVs I am most interested in at this phase of my breeding program are MWWT, PWWT, WFEC, and the USA MAT-HAIR Index. Each is defined below.

  • MWWT – Maternal Weaning Weight EBV – estimates the genetic merit for mothering ability. This EBV mainly reflects genetic differences in ewe milk production, but other aspects of maternal behavior are also involved. A higher number generally indicates more milk production and/or higher quality milk.
  • PWWT –Post-weaning Weight EBV – combines information on pre-weaning and post-weaning growth to predict genetic merit for post-weaning lamb weight. Your target lamb selling weight should strongly influence the desired level of post-weaning gain.
  • WFEC – Weaning Fecal Egg Count EBV – evaluates parasite resistance based on worm egg counts at weaning or early post-weaning. The lower the number, the fewer parasite eggs and less vulnerable the animal will be to parasites. WFEC and the PFEC are important for everyone with sheep grazing in areas where parasites are a problem.
  • USA MAT-HAIR Index – combines EBVs for various traits into an index designed to maximize pounds of lambs weaned per ewe. The ewe productivity index gives substantial positive weight to Number of Lambs Weaned, Maternal Weaning Weight, and Weaning Weight EBVs.

I went overkill last year and gathered more data than I needed. I wanted to see if there were significant differences in the lambs’ rankings based on when the data was gathered. This year, I am limiting my data collection to weights at birth, 60-day, and 90-day, and FECs to 90 days.

Using My NSIP Data

NSIP helps me rank my sheep by one trait or another. This allows me to cull those at the bottom without spending time doing visual appraisal of those poor performers. I still use my eyes and good sense when sorting those at the top, because EBVs tell you nothing about conformation. EBVs have helped me see my breeding flock with a different lens. I found that some rams produced lambs with excellent parasite resistance, but slower growth. Some produced lambs with just the opposite, or lambs that fell in the middle on one or both traits.

It was easy to select this group of ram lambs to be culled based on their EBVs.

I’ve sent in my first set of data for my fall 2022 and spring 2023 lambs, and I know the information I get back will be tremendously helpful in my decision-making. I look forward to comparing EBVs for my breeding flock last year to this year, as they’ve produced additional lambs.

My Offer

While my accuracy scores are currently zero, that will change over time as I continue to submit data. However, it would go even faster if other St. Croix breeders were to join the program and we were to trade sheep (especially rams) between our flocks. So, I have an offer. If you own sheep from my farm, I will reimburse you $50 when you join NSIP, submit data for all your lambs born in 2023 or 2024, and send your report to me. Contact me if this is something that interests you!