1. Breeding “better” sheep SUSAN SCHOENIANSheep & Goat SpecialistWestern Maryland Research & Education CenterUniversity of Maryland Extensionsschoen@umd.edu – www.sheepandgoat.com

2. Defining “better” Better for what? Nature vs. nurture Genetics vs. environment Ways to genetically improve sheep Crossbreeding Selection Today’s topics

3. What is “better”?(according to Google™) Something superior in quality, condition, or effect. From a position of superiority or authority. The superior one of two alternatives. Superior to another (of the same class or kind) in excellence, quality, desirability, or suitability.

4. The U.S. Sheep IndustryAmerican Sheep Industry Association Survey, April 2010

5. Why do you raise sheep? Commercial Meat Wool Seedstock (show) Club lambs Dairy production

6. Commercial meat production Important Performance Reproductive efficiency LBS. QUALITY LAMB WEANED Growth and carcass (sire) Post-weaning ADG Market suitability Fitness Disease-resistant Longevity Easy-care Less important (ewes) Body conformation Wool

7. wool production Important Wool Quality Quantity Color Character Less important Body conformation Reproductive efficiency Fitness

8. Seedstock (show animals) Important Body conformation Frame size Structural correctness Muscling Whatever the current “fad” for your breed is. Less important Reproductive efficiency Fitness Wool production

9. Club lambs Important Type Body conformation Eye appeal (“X” factor) Less important Reproductive efficiency Fitness Wool

10. Dairy Important Milk production Quantity Quality Udder conformation Disposition Less important Body conformation Wool Fitness

11. Nature vs. nurtureHeredity (genetics) vs. environment GENOTYPE The genetic make-up of an individual. The genes or alleles present in an individual. An individual’s genetic information. PHENOTYPE Physical appearance of an individual. Observable or measurable traits. Genetics + environment

12. Environmental factors affecting phenotype Nutrition Health Weather Season Management Housing Pasture management Age Genetics is permanent. The environment changes.

13. Nature vs. nurture Phenotype Genotype What an animal looks like Visual appraisal How an animal performs Actual performance levels On-farm Adjusted weaning weights Adjusted litter weights Flock EPDs (expected progeny difference). Across-flock EPDs or EBVs Differences in performance at Central Ram Test Stations Individual genes Fecundity gene Myostatin gene Scrapie-resistance

17. Heterosis in the crossbred ewe

19. Strengths of sire breed offset weaknesses of dam breed and vice versa.Suffolk x Katahdin Finn x Dorset Suffolk x Texel

21. Qualitative vs. quantitative traits Qualitative Controlled by few genes Categorical scale Distinct traits Quantitative Influenced by genetics and environment Controlled by many genes Continuous traits Most traits of economic importance.

22. Selection: Heritability Phenotypic variation due to genetic differences. Relationship between phenotype and genotype. Percent of phenotypic variation that is transferred to the next generation. Degree to which offspring resemble parents Sire and offspring

23. Selection: heritablity Individual ewes and rams pass on traits to their offspring based on the heritability of those traits. Traits which respond well to crossbreeding (hybrid vigor) do not respond as well to selection and vice versa. Heritability is higher for wool traits, growth, and carcass traits, and lower for reproductive and fitness traits. Faster progress can be made for traits with high heritability, though lowly heritable traits should not be ignored, as they still have a genetic component.

24. Traits with low heritability, < 20%

25. Traits with moderate heritability, 20-40%

26. Traits with high heritability, > 40 %

28. Tools for genetic improvement On-farm performance testing Carcass contests Central performance tests Across-flock genetic comparisons (EPDs)

29. On-farm performance testing Weaning weights Age Sex Type of birth and rearing Age of dam. Post-weaning ADG Parasite resistance (fecal egg counts) Parasite resistance (FAMACHA© scores and Tx) Carcass characteristics Fleece characteristics

30. Contemporary groups Same breed or breed type Same environment Same management group Same feeding program Same season

31. Central ram performance tests Mostly for terminal sire and dual-purpose breeds. Virginia West Virginia Pennsylvania Midwest West Growth and feed efficiency Ultrasound carcass Fleece characteristics Type scores Scrapie and spider genotype

32. EPDs Expected Progeny Differences National Sheep Improvement Association (NSIP) - www.nsip.org Submit data through breed associations Breed association determines which traits are important Not all breeds participate (minor breeds) Across-breed performance evaluation

33. Thank you for your attention.Do you have any questions?