1. Gene350 Animal Genetics Lecture 15 31 August 2009

2. Last Time Single genes in Animal Breeding – Examples and uses

3. Today Inheritance of Quantitative traits in animals – Heritability – Repeatability

4. Inheritance of Quantitative Traits Quantitative traits can be measured genetically determined by many gene pairs.

5. Inheritance of Quantitative Traits P = G + E Phenotype = Genotype + Environment P = A + D + I + E P = additive + dominance + epistasis + E.

6. Inheritance of Quantitative Traits GenotypeValue AA+4 Aa+2 aa+0 Additive.

7. Inheritance of Quantitative Traits GenotypeValue BB+4 Bb+4 bb+0 Complete Dominance.

8. Inheritance of Quantitative Traits GenotypeValue CC+4 Cc+3 cc+0 Partial dominance.

9. Inheritance of Quantitative Traits GenotypeValue DD+4 Dd+6 dd+0 Overdominance.

10. Inheritance of Quantitative Traits P = A + D + I + Ep +Et Ep = permanent environment Et = temporary environment.

11. Inheritance of Quantitative Traits Permanent environment environmental effect on all subsequent records Temporary environment environmental effect on current record P = A + D + I + Ep +Et.

12. Inheritance of Quantitative Traits Permanent environmental effects severe illness failure to have a calf one year injury to udder frostbite Temporary environmental effect heat wave slight illness off feed.

13. Variation in a herd Vp = Vg + Ve phenotypic variance genetic variance environmental variance.

14. Variation in a herd Vp = Va + Vd + Vi + Vep + Vet additive variance dominance variance epistatic variance permanent environmental variance temporary environmental variance.

16. Variation in a herd normal distribution of phenotypes underlying normal distributions of additive effects dominance effects epistatic effects perm env effects temp env effects.

17. Variation in a herd best animals may have best additive genotype best dominance genotype best epistatic genotype best perm env best temp env and/or best combination of these effects.

19. heritability = define - proportion of phenotypic variation that is due to additive gene effects most important concept in Animal Genetics.

20. proportion of phenotypic variation that is due to additive gene effects = Heritability traitsh 2 magnitude reproductive<.2low growth.2-.4moderate carcass.4-.6high few traits have h 2 >.6

21. proportion of phenotypic variation that is due to additive gene effects = beef cattleh 2 birth weight.35 weaning weight.30 weaning score.25 feedlot gain.45 carcass grade.40 fat thickness.33 rib eye area.58 marbling.42 retail product %.30 calving interval.08 conception rate.05

22. proportion of phenotypic variation that is due to additive gene effects = Dairy cattleh 2 milk yield.25 fat yield.25 solids-not-fat yield.25 protein yield.25 fat %.50 solids-not-fat %.50 protein %.50 type score.30

23. proportion of phenotypic variation that is due to additive gene effects = Swineh 2 ovulation rate.39 litter size.10 survival to weaning.05 21-day litter wt.15 average daily gain.30 days to 230 pounds.25 backfat thickness.41 feed efficiency.30 loin eye area.47 carcass length.56

24. proportion of phenotypic variation that is due to additive gene effects = Sheeph 2 90-day weight.25 postweaning gain.40 grease fleece wt.35 fiber diameter.40 staple length.55 fat thickness.30 loin eye area.50 ewe fertility.05 prolificacy.10 lamb survival.05 carcass weight.35 dressing %.10

25. proportion of phenotypic variation that is due to additive gene effects = Horseh 2 pulling ability.25 cutting ability.04 Thoroughbred earnings.09 handicap wt.33 Trotter earnings.20 time.32 wither height.43 heart girth.29 services / conceptions.12

26. proportion of phenotypic variation that is due to additive gene effects = Layersh 2 chick livability.05 adult livability.10 body depth.25 adult body weight.55 egg production.15 egg weight.55 fertility.05 Broilers 7-week weight.45 feed consumption.70 feed conversion.35 breast fleshing.10 fat deposition.50

27. Repeatability proportion of phenotypic variance due to all permanent effects

28. Contrast between h 2 and r e repeatability > heritability heritability association between parent and offspring repeatability association between adjacent records on an individual.

29. Repeatability only important for repeated traits repeated traits those measured more than once milk production egg production.

30. Repeatability if repeatability = 1 next year’s record will be the same (relative to mean) as this year’s if repeatability = 0 this year’s record tells us nothing about future records.

31. Phenotypic correlation association between actual performance for two traits Genetic correlation association between genetic merit for two traits.

32. Genetic correlation caused by linkage pleiotropy genes that affect more than one trait.

33. Genetic correlation if traits have a non-zero genetic correlation selection for one trait yields change in the other trait.

34. Beef cattle BWWWADGFATREA birth weight.46.01 weaning weight.42.46.04.74GENETIC feedlot gain.12.20-.05.49CORR. fat thickness.01.18-.30 rib eye area.08.20-.30 PHENOTYPIC CORRELATION

35. SWINEADGAGEBFFELEA average daily gain-.93.22-.70-.10G days to 230 pounds -.90-.20.65.05E backfat thickness.20-.18.34-.35N feed efficiency -.65.60.25-.35E loin eye area -.06.03-.28-.20T I PHENOTYPIC CORRELATIONC