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Applied Beef Cattle Breeding and Selection Inbreeding and Heterosis in Beef Cattle

Applied Beef Cattle Breeding and Selection Inbreeding and Heterosis in Beef Cattle. Larry V. Cundiff ARS-USDA-U.S. Meat Animal Research Center. 2008 Beef Cattle Production Management Series-Module IV Great Plains Veterinary Education Center University of Nebraska, Clay Center August 1, 2008.

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Applied Beef Cattle Breeding and Selection Inbreeding and Heterosis in Beef Cattle

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  1. Applied Beef Cattle Breeding and Selection Inbreeding and Heterosis in Beef Cattle Larry V. Cundiff ARS-USDA-U.S. Meat Animal Research Center 2008 Beef Cattle Production Management Series-Module IV Great Plains Veterinary Education Center University of Nebraska, Clay Center August 1, 2008

  2. Homework

  3. Email homework to larry.cundiff@ars.usda.gov

  4. Self Fertili- zation Half sib Random Mating In a pure breed Cross breeding Degrees of inbreeding according to relationship of mates (Lush, 1945) Species crosses Outbreeding within a breed First cousin Full sib

  5. Change in genotypic frequency with self fertilization

  6. Effects of different degrees of dominance on phenotypic value No Dominance (additive) Partial dominance Complete dominance

  7. Effects of inbreeding on heterozygosity/homozygosity (Cundiff and Gregory, 1977) H E T E R O Z Y G O S I T Y (%) Aa H O M O Z Y G O S I T Y (%) AA Or aa 100 0 ? 80 20 60 40 40 60 20 80 100 0 Pure Breed Random mated Cross breeding Sire Daughter Or Full sib Inbred Line F = .5 Homo- Zygous line ?

  8. Effects of inbreeding in cattle (Brinks et al., 1975. Western Regional Project W-1, Tech. Bulletin 123) • Fertility (percentage of cows pregnant declined 2% and 1.3% with each 10% increase in inbreeding of the dam and calf, respectively. • Percentage calf crop weaned declined 1.6% and 1.1% with each 10 percent inbreeding of the dam and calf, respectively. • Inbreeding also depressed growth and maternal weaning weight.

  9. Estimating Heterosis for a specific two breed cross HA = 430 = .5gH + .5 gA + hIha + mA AH = 416 = .5gH + .5 gA + hIha + mH AA = 405 = gA + + mA HH = 395 = gH + + mH (.5)(HA + AH) + .5 (AA + HH) = 423 – 400 = 23 = hIah

  10. Estimating Maternal Heterosis C X A = .5gC + .5 gA + hIca + mA C X B = .5gC + .5 gB + hICB + mB C X AB = .5gC + .25 gA + .25gB + .5hIAC + .5hIBC + .5mA + .5 mB + hMAB C X BA = .5gC + .25 gB + .25gA + .5hIAC + .5hIBC + .5mA + .5 mB + hMAB .5[( C X AB) + (C X BA)] – .5[(C X A) + (C X B)] = hMAB

  11. HETEROSIS EFFECTS IN CROSSES OF BOS TAURUS X BOS TAURUS BREEDS AND IN CROSSES OF BOS INDICUS X BOS TAURUS BREEDS FROM DIALLEL CROSSING EXPERIMENTS Bos taurus XBos indicus X No. Bos taurus No. Bos taurus Trait Est. Units % Est. Units % Crossbred calves (individual heterosis) Calving rate, % 11 3.2 4.4 Survival to weaning, % 16 1.4 1.9 Birth weight, kg 16 .8 2.4 4 3.3 11.1 Weaning weight, kg 16 7.3 3.9 10 21.7 12.6 Postweaning ADG, g/d 19 34 2.6 6 116 16.2 Yearling weight, kg 27 13.2 3.8 Cutability, % 24 -.3 -.6 Quality grade, 1/3 gr. 24 .12 --- 6 .3 ---

  12. HETEROSIS EFFECTS IN CROSSES OF BOS TAURUS X BOS TAURUS BREEDS AND IN CROSSES OF BOS INDICUS X BOS TAURUS BREEDS FROM DIALLEL CROSSING EXPERIMENTS Bos taurus XBos indicus X No. Bos taurus No. Bos taurus Trait Est. Units % Est. Units % Crossbred cows (maternal heterosis) Calving rate, % 13 3.5 3.7 7 9.9 13.4 Survival to weaning 13 .8 1.5 7 4.7 5.1 Birth weight, kg 13 .7 1.8 6 1.9 5.8 Weaning weight, kg 13 8.2 3.9 12 31.1 16.0 Longevity, yrs 3 1.36 16.2 Lifetime prod. No. Calves 3 .97 17.0 Cum. wn. wt., kg 3 272 25.3

  13. Heterosis Weight of Calf Weaned Per Cow Exposed To Breeding 23.3 • Heterosis increases production per cow 20 to 25% in Bos taurus x Bos taurus crosses and at least 50% in Bos indicus x Bos taurus crosses in subtropical regions. • More than half of this effect is dependent on use of crossbred cows. 14.8 Percent 8.5 8.5 X-bred cows X-bred calves Straightbred cows straightbred calves Straightbred cows X-bred calves

  14. LONGEVITY AND LIFETIME PRODUCTION OFSTRAIGHTBRED HEREFORD (H), ANGUS (A), HEREFORD X ANGUS (HA) AND ANGUS X HEREFORD (AH) COWS Breed group Trait H A HA AH Heterosis Longevity, yrs. 8.4 9.4 11.0 10.6 1.9* Lifetime production No. calves 5.9 6.6 7.6 7.6 1.3* Wt of calves weaned, lb. 2405 2837 3259 3515 766* *P < .05

  15. Conclusions • Heterosis Effects are greatest for lowly heritable traits: • Reproduction • Survival • Longevity • Heterosis effects are moderate for moderately • heritable traits: • Direct and maternal weaning weight • Postweaning gain • Heterosis effects are small for highly heritable traits: • Feed efficiency • Carcass traits • Retail product % • Fat thickness • Marbling

  16. Static Three-breed Cross System C B A AB A A   45-50% of Cows 25-30% of Cows 25% of Cows     Offspring marketed Pounds of calf/cow increased about19%

  17. Rotational Crossbreeding Systems

  18. Heterosis for Production Per Cow in Hereford, Angus, and Shorthorn Rotational Crosses First Generation Observed (%) 16 24 Expected (%)a 19 23 Second Generation Observed (%) 24 35 Expected (%)a 14 21 aBased on individual and maternal heterosis observed in F1 generation and assumes that retained heterosis is proportional to retained heterozygosity. Two breed Three breed rotation rotation

  19. Genetic Composition and Heterosis Expected in a Two-Breed Rotation Heteroz. of Est. Additive genetic progeny in wt. comp. of progenyrelative to F1 wnd/cowa Sire A B Generation breed % % % % 1 A 50 50 100 8.5 2 B 25 75 50 19.0 3 A 63 37 75 13.8 4 B 31 69 63 16.4 5 A 66 34 69 15.2 6 B 33 67 66 15.8 7 A 67 33 67 15.5 aBased on heterosis effects of 8.5% for individual traits and 14.8% for maternal traits, when loss of heterosis in proportional to loss of heterozygosity

  20. Genetic Composition and Heterosis Expected in a Three-Breed Rotation Additive Genetic Heteroz. of Est. increase Comp. of Progeny progeny in wt. Sire A B C relative to F1wnd/cowa Generation breed % % % % % 1 A 50 0 50 100 8.5 2 B 25 50 25 100 23.3 3 C 12 25 62 75 21.2 4 A 56 12 31 88 18.6 5 B 28 56 16 88 20.5 6 C 14 28 58 84 20.2 7 A 57 14 29 86 19.7 8 B 29 57 14 86 20.0 aBased on heterosis effects of 8.5% for individual traits and 14.8% for maternal traits when loss of heterosis is prportional to loss of heterozygosity.

  21. Rotational Crossbreeding Systems

  22. Rotational crossing systems maintain heterosisproportional to heterozygosity

  23. Next time : Composite Populations and alternative crossbreeding systems.

  24. MARC I ¼ Limousin, ¼ Charolais, ¼ Brown Swiss, c Angus and c Hereford MARC II ¼ Simmental, ¼ Gelbvieh, ¼ Hereford and ¼ Angus MARC III ¼ Pinzgauer, ¼ Red Poll, ¼ Hereford and ¼ Angus Limousin Simmental Pinzgauer Charolais Gelbvieh Red Poll Brown Swiss (Braunvieh) Hereford Hereford Angus Angus Angus Hereford

  25. HETEROSIS EFFECTS AND RETAINED HETEROSISIN COMPOSITE POPULATIONS VERSUS CONTRIBUTINGPUREBREDS (Gregory et al., 1992) Composites minus purebreds Trait F1 F2 F3&4 Birth wt., lb 3.6 5.0 5.1 200 d wn. wt., lb 42.4 33.4 33.7 365 d wt., females, lb 57.3 51.4 52.0 365 d wt., males, lb 63.5 58.6 59.8 Age at puberty, females, d -21 -18 -17 Scrotal circumference, in .51 .35 .43 200 d weaning wt., (mat.), lb 33 36 Calf crop born, (mat.), % 5.4 1.7 Calf crop wnd., (mat.), % 6.3 2.1 200 d wn. wt./cow exp. (mat.), lb 55 37

  26. Composite populations maintain heterosisproportional to heterozygosity(n-1)/n or 1 – S Pi2

  27. Rotational crossing systems or composite populations maintain significant heterosis

  28. MODEL FOR HETEROZYGOSITY IN A TWO BREED COMPOSITE Breed Breed of sire Dam ½ A ½ B ½ A ¼ AA ¼ AB ½ B ¼ BA ¼ BB (n-1)/n or 1 – S Pi2 = .50

  29. MODEL FOR HETEROZYGOSITY IN A THREE BREED COMPOSITE Breed Breed of sire Dam .50 A .25 B .25 C .50 A .25 AA .125 BA .125 CA .25 B .125 BA .0625BB .0625 CB .25 C .125 AC .125 BC .0625CC 1 – S Pi2 = (1 - .375) = .625

  30. Weaning Wt Marketed Per Cow Exposed for Alternative Crossbreeding Systems Relative to Straightbreeding (%) Wean. wt H i Hm marketed System (+ 8.5%) (+14.8%) per cow exp Straight breeding 0 0 0 2-breed rotation (A,B) .67 .67 15.5 3-breed rotation (A,B,C) .86 .86 20.0 4-breed rotation (A,B,C,D) .93 .93 21.7 2-breed composite (5/8 A, 3/8 B) .47 .47 11.0 2-breed composite (.5 A, .5 B) .5 .5 11.7 3-breed composite (.5A, .25 B, .25C) .625 .625 14.6 4 breed composite (.25A,.25B,.25C,.25D) .75 .75 17.5 F1 bull rotation (3-breed: AB, AC) .67 .67 15.5 F1 bull rotation (4-breed: AB, CD) .83 .83 19.3

  31. Composite populationsprovide for effective use of • Heterosis • Breed differences • Uniformity and end product consistency

  32. Genetic Variation in Alternative Mating Systems Optimum Assumes that the Two F1’s Used are of Similar Genetic Merit

  33. Genetic potential for USDA Quality Grade and USDA Yield Grade is more precisely optimized in cattle with 50:50 ratios of Continental to British breed inheritance.

  34. COMPLEMENTARITY is maximized in terminal crossing systems Terminal Sire Breed Rapid and efficient growth Optimizes carcass composition and meat quality in slaughter progeny • Cow Herd • Small to moderate size • Adapted to climate • Optimal milk production • for feed resources Progeny Maximize high quality lean beef produced per unit feed consumed by progeny and cow herd

  35. Rotational and Terminal Sire Crossbreeding Programs Two Breed Composite Cow Age No. 1 20 2 18 3 15 2Breed Rotation  A B 1/2A - 1/2B  45% 4 13 5 12 - - - - 12 1 T x (A-B) T x (A-B) 55% Lbs. Calf/Cow 18% 21%

  36. Weaning Wt Marketed Per Cow Exposed for Alternative Crossbreeding Systems Relative to Straightbreeding (%) Wean. wt Terminal H i Hm marketed crossa System + 8.5% +14.8% per cow exp (+5% wt/calf) Straight breeding 0 0 0 0 2-breed rotation (A,B) .67 .67 15.5 20.8 3-breed rotation (A,B,C) .86 .86 20.0 24.1 4-breed rotation (A,B,C,D) .93 .93 21.7 25.4 2-breed composite (5/8 A, 3/8 B) .47 .47 11.0 17.3 2-breed composite or F1 bulls (.5 A, .5 B) .5 .5 11.7 17.8 3-breed composite (.5A, .25 B, .25C) .625 .625 14.6 20.3 4 breed composite (.25A,.25B,.25C,.25D) .75 .75 17.5 22.2 F1 bull rotation (3-breed: AB, AC) .67 .67 15.5 20.8 F1 bull rotation (4-breed: AB, CD) .83 .83 19.3 23.6 a Assumes 66 % of calves marketed (steers and heifers) are by terminal sire breed out of more mature age dams and 33% are by maternal breeds (steers only).

  37. SUMMARY

  38. Figure 6. Use of heterosis, additive breed effects and Complementarity with alternative crossbreeding systems.

  39. Implications for Crossbreeding • Similarity in mean performance of British and Continental European breeds means they are more suited for use in rotational cross-breeding systems today than 30 years ago • Performance levels are not expected to fluctuate as much with rotational crossing for growth traits and cow size . Growth rate can be stabilized by using Across-breed EPDs. • Differences in birth weight are still significant and warrant use of sire breeds with lighter birth weight on first calf heifers (i.e., Angus, Red Angus, etc.). • Intergeneration fluctuations in milk production still persist but they are less than half as great as 30 years ago. Milk levels can be stabilized by using Across-breed EPDs.

  40. Implications for Crossbreeding • Advantages of terminal sire crossing systems are not as great today as 30 years ago due to similarity of breeds for rate and efficiency of growth. • However, differences between British and Continental breeds in carcass traits are still significant and relatively large. • Inter generation fluctuations in mean performance for carcass traits are still large and significant. • For carcass traits, uniformity and end-product consistency can still be enhanced by use of composite populations or hybrid bulls. • Adaptation to intermediate subtropical/temperate environments can be optimized with greater precision by use of composite populations or hybrid bulls.

  41. Heterosis proportional to heterozygosity in various matings Mating type Progeny Dam Pure breed 0 0 Two breed F1 cross (A x B) 100 0 F2 (AB x AB) 50 100 F3 (AB x AB) (or F4, ..Fn) = 2 breed Composite 50 50 Backcross (A x AB) 50 100 1st backcross interse (A-AB x A-AB) 37.5 50 ¾-1/4 composite (.75A, .25B) 37.5 37.5 5/8-3/8 composite (.625 A, .375 B) 47 47 2 breed rotation 67 67 Three way cross (A x BC) 100 100 1st 3-way interse (A - BC) x (A-BC) 62.5 100 3 –breed composite (.5 A, .25 B, .25C) 62.5 62.5 3 breed rotation (A, B, C) 86 86 Rotation F1 hybrids, 1 common breed (AB -AC) 67 67 Four way cross 100 100 4- breed composite (.25 A, .25B, .25C, .25 D) 75 75 4-breed rotation (A, B, C, D) 93 93 Rotation 2 F1 hybrids (AB - CD) 83 83

  42. Rotational and Terminal Sire Crossbreeding Programs Cow Age No. 1 20 2 18 3 15 2Breed Rotation 3 Breed Rotation  B A B    45%  A C 4 13 5 12 - - - - 12 1 T x (A-B) T x (A-B-C) 55% Lbs. Calf/Cow 24% 21%

  43. BREED DIFFERENCES an important genetic resource • Cross breeding of composite populations can be used to exploit: • HETEROSIS • COMPLEMENTARITY among breeds optimize performance levels for important traits and to match genetic potential with: • Market preferences • Feed resources • Climatic environment

  44. Composite populationsprovide for effective use of • Heterosis • Breed differences • Uniformity and end product consistency

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