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The U.S. National Sheep Improvement Program: across-flock genetic evaluations and new trait development
1Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg 24061-0306, USA.
Journal of Animal Science
|October 22, 1998
Summary
The U.S. National Sheep Improvement Program (NSIP) provides across-flock genetic evaluations for Targhee, Suffolk, and Polypay sheep. These analyses reveal genetic trends and antagonisms, guiding future breeding strategies for improved production traits.
Area of Science:
- Animal Science
- Genetics
- Sheep Breeding
Background:
- The U.S. National Sheep Improvement Program (NSIP) was established in 1987.
- Initial evaluations focused on within-flock genetic assessments.
Purpose of the Study:
- To evaluate NSIP's operating procedures and methodology.
- To implement across-flock, multiple-trait genetic evaluations for Targhee, Suffolk, and Polypay breeds.
Main Methods:
- Across-flock, multiple-trait EPD (Estimated Progeny Differences) were developed.
- Genetic parameters were estimated separately for each breed.
- Single-trait analyses were conducted for number born per ewe lambing.
Main Results:
- Genetic trends from 1987-1995 aligned with breed roles.
- Identified genetic antagonisms, such as fleece weight vs. fiber diameter in Targhee.
- Observed breed-specific changes in body weight, fleece traits, and reproductive performance.
Conclusions:
- NSIP successfully provides valuable across-flock genetic evaluations.
- Genetic antagonisms present challenges for simultaneous trait improvement.
- Future enhancements will focus on accelerated lambing and carcass traits.