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Beef Cattle Breeding Selection Programs

Beef Cattle Breeding Selection Programs. David Buchanan, Professor Department of Animal Science. Beef Cattle Breeding Beef Improvement Federation started in 1968 Organization of people involved in performance testing for beef cattle

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Beef Cattle Breeding Selection Programs

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  1. Beef Cattle BreedingSelection Programs David Buchanan, Professor Department of Animal Science

  2. Beef Cattle Breeding Beef Improvement Federation started in 1968 • Organization of people involved in performance testing for beef cattle • “Guidelines for Uniform Beef Improvement Programs”

  3. Inheritance of Quantitative Traits P = G + E Phenotype = Genotype + Environment Genotype Additive – due to individual genes Non-additive – due to combinations of genes

  4. Variation in a Herd Vp = Va + Vna + Ve Additive variation Non-additive variation Environmental variation

  5. Variation in a Herd Best animals may have: • Best additive genotype • Best non-additive genotype • Best environment and/or • Best combination of these effects

  6. Heritability = Define - proportion of phenotypic variation that is due to additive gene effects

  7. Heritability Traits h2 Magnitude Reproductive < .2 Low Growth .2-.4 Moderate Carcass .4-.6 High Few traits have h2 > .6

  8. Heritability Estimates for Beef Cattle Trait h2 Birth weight 0.35 Weaning weight 0.30 Feedlot gain 0.45 Fat thickness 0.33 Rib eye area 0.58 Marbling 0.42 Calving interval 0.08 Conception rate 0.05 Milk 0.20 Yearling weight 0.40 Feed efficiency 0.38 Tenderness 0.55 Source: Cundiff, L.V. and K.E. Gregory; Lasley, J.F.; Taylor, R.E.

  9. Heritability • Proportion of the superiority in an individual which can be passed on to the offspring. • Proportion of the differences in individuals which is due to genetics (additive). • Only the additive component since a sperm or egg has individual genes, not gene combinations.

  10. Phenotypic Correlation Association between actual performance for two traits Genetic Correlation Association between genetic merit for two traits

  11. Genetic Correlation If traits have a non-zero genetic correlation selection for one trait, yields change in the other trait.

  12. Phenotypic Correlation Beef cattle BW WW ADG FAT REA Birth weight .46 .01 Weaning weight .42 .46 .04 .74 Genetic Feedlot gain .12 .20 -.05 .49 Corr. Fat thickness .01 .18 -.30 Rib eye area .08 .20 -.30 Example: selection for increased ADG increased WW (also improved FE)

  13. Response to Selection R = h2 x S Where: R is the response h2 is the heritability S is the selection differential Selection differential: Difference between individuals selected to be parents and the average of the entire herd

  14. Does Genetic Change Always Yield Phenotypic Change?? Year to year variation causes phenotypic change to vary from year to year.

  15. Generation Interval • Average time to replace a parent in population • Average age of parents when offspring are born • NOT average age when first offspring are born 3-4 years – bulls 4.5-6 years – cows

  16. Response per year = Response per gen / gen int How to increase response: Increase selection differential Reduce generation interval

  17. Adjustment Factors Need to make fair comparisons Corrects for known sources of environmental variation Age of dam Age of individual

  18. Adjustment Factors • Reduce environmental variance • Increase heritability • Increase response to selection

  19. On-farm Testing All producers should have program of identifying superior breeding stock. Uniform management enables identification of superior breeding stock increases effective heritability.

  20. Central Test Stations Bulls from different herds evaluated for postweaning performance Locate and recognize superior bulls evaluate breeding stock from producers demonstrate effective testing practices.

  21. Whole Herd Reporting Compared to traditional reporting of individual animals, whole herd reporting enables understanding of when cows do or do not have calves. Producer submits a “breeding herd inventory”.

  22. Female Production Data • Breeding dates • Pregnancy status - between 50 and 150 days • Calving date • Dystocia score 1-No difficulty 2-Some assist 3-Mechanical assist 4-Surgery 5-Abnormal presentation

  23. Male Reproduction Data • History and physical exam • Injury or abnormality • Evaluation of scrotum and testes • Palpation of internal accessory glands • Exam of the penis • Scrotal circumference • Sperm motility

  24. Sire and Herd Reproduction • Number of cows exposed • Percent palpated pregnant cows pregnant / cows exposed • Live calving percent live calves / (cows exposed – cows sold or died + cows purchased) • Weaning percent live calves / (cows exposed – cows sold or died + cows purchased)

  25. Growth Rate and Efficiency of Gain • Birth weight – indicator of calving difficulty obtained within 24 hours • Weaning weight – measure of both growth and mothering ability • Yearling weight – measure of growth 365 days – feedlot management 452 days 550 days – pasture management

  26. BIF Standard Adjustment Factors for Birth Weight Age of Dam Factor 2 +8 3 +5 4 +2 5-10 0 >10 +3

  27. Weaning Weight 205-day weight = x 205 + BW Add the age of dam adjustment to get adjusted 205-day weight.

  28. Standard Adjustment Factors for Weaning Weight Adjustment Factors Age of Dam Male Calves Female Calves 2 +60 +54 3 +40 +36 4 +20 +18 5-10 0 0 >10 +20 +18

  29. Yearling Weight 365-day weight = x 160 + adjusted 205-day wt

  30. Postweaning Feed Efficiency. • Critically important trait • Difficult to measure requires individual feed intake • Selection for rapid growth improved feed efficiency also increased mature size

  31. Carcass Evaluation • Product quality • Prime • Choice • Select • Standard • Marbling • Major determinant of quality • Color • Firmness • Texture • Maturity

  32. Carcass Evaluation • Yield grade • Fat thickness • KPH fat • Hot carcass weight • Rib eye area

  33. Live Animal Evaluation • Measurements and subjective evaluations • Frame size • Classification system for hip heights • Scrotal circumference • Indicator of sperm production and age at puberty • Pelvic area • Predictor of calving difficulty

  34. National Cattle Evaluation • Goal – compare cattle from different herds • Conducted by breed associations • Depends on use of AI to make comparisons between herds .

  35. Use of a Reference Sire to Compare Between Herds Herd 1 Herd 2 Herd 3 Reference sire Bull A Bull A Bull A Avg. calf weight 450 500 550 Home sire Bull 1 Bull 2 Bull 3 Avg. calf weight 460 480 500 Rank 1 (+10) 2 (-20) 3 (-50)

  36. Estimated Breeding Value • Actual genetic merit never known • Estimate breeding value based upon: • Individual performance • Performance of relatives • Parents, sibs, progeny etc.

  37. EPD - Expected Progeny Difference = 1/2 of Estimated Breeding Value merit of an animal, in comparison with others Bull 1 Bull 2 EBV = 20 EBV = 0 EPD = 10 EPD = 0 Calves expected to differ by 10 pounds EPDs used to compare animals

  38. Accuracy • Measure of confidence in an estimate of breeding value • Range of possible values 0 to 1

  39. Accuracy and Possible Change Accuracy is a correlation (between true breeding value and estimated breeding value). (0 to 1) Possible change is a standard deviation gives a 68% confidence interval. Best possible change would be 0. .

  40. Fixed Base Point What is the meaning of EPD = 0? 0 is not current average; 0 is average at initiation of data collection; or 0 is a fixed date.

  41. Base Point in Angus 0 is average in 1979 Angus EPDs are deviations from 1979 mean.

  42. Angus Bull, 2004 Sire Summary

  43. Summary of Growth and Mature Size EPD from Multiple U.S. Beef Cattle Breed Associations Genetic Evaluations Breed Birth Weaning Milk Total Yearling Mature Angus X X X X X X Beefmaster X X X X Braford X X X X X Brangus X X X Braunvieh X X X X X Blonde d’Aquitaine X X X X X Brahman X X X X Charolais X X X X X Gelbvieh X X X X X Hereford X X X X X Limousin X X X X Red Angus X X X X X Red Brangus X X X X X Romagnola X X X X X Salers X X X X X Santa Gertrudis X X X X X Shorthorn X X X X X Simbrah X X X X X X Simmental X X X X X X SouthDevon X X X X X Tarentaise X X X X X Source: Center for Genetic Evaluation of Livestock, Colorado State Univ.

  44. Summary of Reproductive EPD from Multiple U.S. Beef Cattle Breed Associations Genetic Evaluations Breed Calving Calving Ease Gestation Heifer Scrotal Ease Daughters Docility Length Pregnancy Circ Stayability Angus X X Beefmaster X Brangus X Charolais X Gelbvieh X X X X X Hereford X X X Limousin X X X X Red Angus X X X X Salers X X X Shorthorn X X X Simmental X X Tarentaise X Source: Center for Genetic Evaluation of Livestock, Colorado State University.

  45. Summary of End Product EPD from Multiple U.S. Beef Cattle Breed Associations Genetic Evaluations Breed Fat Marbling Rib Eye Carcass Retail Grid Thickness Score Area Weight Tenderness Yield Merit Angus X X X X X Brangus X X Charolais X X X X Gelbvieh X X X X X Hereford X X X Limousin X X X X Red Angus X X X Salers X X X X X Senepol X X X Shorthorn X X X X X Simbrah X X X X X X Simmental X X X X X X South Devon X X X Wagyu X X X American Angus Association publishes separate EPD for ultrasound traits. Source: Center for Genetic Evaluation of Livestock, Colorado State University

  46. Use of EPDs Purebred herds Use a balance of traits Be aware of needs of commercial customers Provide good data to breed association

  47. Use of EPDs ― Commercial Herds Recommendations for EPD for Various Commercial Scenarios Use of Individual Birth Weaning Yearling Milk Terminal sire on mature cows Not too high High High Not relevant Bull to use with heifers Low Moderate Moderate Mod – high Sire replacement heifers Low – mod Mod – high Mod- high Mod - high

  48. Beef Cattle BreedingMating Systems

  49. Inbreeding Mating of related individuals Mating of individuals more closely related than the average of the breed Animal is inbred if, and only if, its parents are related.

  50. Measurement of Inbreeding Inbreeding coefficient (F) % increase in homozygocity above the average of the breed If F = .25, the animal is 25% more homozygous than the average of the breed

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