HETEROSIS EFFECTS AND RETAINED HETEROSIS IN COMPOSITE POPULATIONS VERSUS CONTRIBUTING PUREBREDS Gregory et al., 1992 .


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Applied Beef Cattle Breeding and Selection Composite Populations . Larry V. Cundiff ARS-USDA-U.S. Meat Animal Research Center. 2008 Beef Cattle Production Management Series-Module V Great Plains Veterinary Education Center University of Nebraska, Clay Center September 18, 2008.
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Connected Beef Cattle Breeding and Selection Composite Populations Larry V. Cundiff ARS-USDA-U.S. Meat Animal Research Center 2008 Beef Cattle Production Management Series-Module V Great Plains Veterinary Education Center University of Nebraska, Clay Center September 18, 2008

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Estimating Heterosis for a particular two breed cross HA = 430 = .5g H + .5 g A + h I ha + m An AH = 416 = .5g H + .5 g A + h I ha + m H AA = 405 = g A + m A HH = 395 = g H + m H (.5)(HA + AH) - .5 (AA + HH) = 423 – 400 = 23 = h I ah

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HA = 430 = .5g H + .5 g A + h I ha + m An AH = 416 = .5g H + .5 g A + h I ha + m H AA = 405 = g A + m A HH = 395 = g H + m H In the above conditions, HA signifies a crossbred calf with a Hereford sire and an Angus dam. Ok means a crossbred calf with an Angus sire and a Hereford dam. HH means a straightbred calf with a Hereford sire and Hereford dam. AA indicates a straightbred calf with an Angus sire and Angus dam. g H indicates the added substance breed impact for Herefords and g A the added substance breed impact for Angus. h I ha signifies impact of individual hetersosis communicated by Hereford X Angus or Angus X Hereford proportional crosses. Take note of that h I ha = h I ha . m A signifies the maternal (MILK) breed impact for Angus and m H the maternal breed impact for Hereford dams.

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Estimating Maternal Heterosis C X A = .5g C + .5 g A + h I ca + m A C X B = .5g C + .5 g B + h I CB + m B C X AB = .5g C + .25 g A + .25g B + .5h I AC + .5h I BC + .5m A + .5 m B + h M AB C X BA = .5g C + .25 g B + .25g A + .5h I AC + .5h I BC + .5m A + .5 m B + h M AB .5[( C X AB) + (C X BA)] – .5[(C X A) + (C X B)] = h M AB

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C X A = .5g C + .5 g A + h I ca + m A C X B = .5g C + .5 g B + h I CB + m B C X AB = .5g C + .25 g A + .25g B + .5h I AC + .5h I BC + .5m A + .5 m B + h M AB C X BA = .5g C + .25 g B + .25g A + .5h I AC + .5h I BC + .5m A + .5 m B + h M AB In the above conditions, the g A , g B and g C mean added substance breed impacts for breeds A, B and C separately. h I CA , h I CB and h I AC indicate singular heterosis impacts for C X An (or A X C) , C X B (or B X C) , and A X C (or C X A) breed crosses, individually. m An and m B signify maternal (MILK) breed impacts for breeds An and B, individually. h M AB signifies maternal heterosis communicated by A X B (or B XA) crossbred dams.

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Composite populaces can be utilized to adventure: HETEROSIS COMPLEMENTARITY among breeds enhance execution levels for vital attributes and to coordinate hereditary potential with: Market inclinations Feed assets Climatic environment

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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 Angus Hereford

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HETEROSIS EFFECTS AND RETAINED HETEROSIS IN COMPOSITE POPULATIONS VERSUS CONTRIBUTING PUREBREDS (Gregory et al., 1992) Composites short thoroughbreds Trait F 1 F 2 F 3&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., guys, lb 63.5 58.6 59.8 Age at adolescence, females, d -21 -18 -17 Scrotal boundary, in .51 .35 .43 200 d weaning wt., (tangle.), lb 33 36 Calf edit conceived, (tangle.), % 5.4 1.7 Calf trim wnd., (tangle.), % 6.3 2.1 200 d wn. wt./dairy animals exp. (tangle.), lb 55 37

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Composite populaces keep up heterosis corresponding to heterozygosity (n-1)/n or 1 – S P i 2

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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 P i 2 = .50

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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 .0625 BB .0625 CB .25 C .125 AC .125 BC .0625 CC 1 – S P i 2 = (1 - .375 ) = .625

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Weaning Wt Marketed Per Cow Exposed for Alternative Crossbreeding Systems Relative to Straightbreeding (%) Wean. wt H i H m promoted System (+ 8.5%) (+14.8%) per dairy animals exp Straight breeding 0 0 0 2-breed turn (A,B) .67 .67 15.5 3-breed revolution (A,B,C) .86 .86 20.0 4-breed pivot (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 pivot (3-breed: AB, AC) .67 .67 15.5 F1 bull pivot (4-breed: AB, CD) .83 .83 19.3

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Composite populaces accommodate powerful utilization of Heterosis Breed contrasts Uniformity and final result consistency

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Genetic Variation in Alternative Mating Systems Optimum Assumes that the Two F 1 \'s Used are of Similar Genetic Merit

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Genetic potential for USDA Quality Grade and USDA Yield Grade is all the more absolutely improved in cows with 50:50 proportions of Continental to British breed legacy.

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CEFFICIENTS OF VARIATION IN PUREBRED AND COMPOSITE POPULATIONS (Gregory et al., 1992) Trait Purebreds Composites Gestation length, d .01 .01 Birth wt. .11 .12 200 d wn. wt. .09 .09 365 d wt., females .08 .08 365 d wt., males .09 .09 Age at pubescence (females) .08 .07 Scrotal circumference .07 .07 5 yr dairy animals wt, lb .07 .08 5 yr tallness, in .02 .02 Steer corpse wt, lb .08 .08 Rib-eye area .10 .10 Retail item, % .04 .06 Retail item, lb .19 .20

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COMPLEMENTARITY is expanded in terminal intersection frameworks Terminal Sire Breed Rapid and proficient development Optimizes cadaver arrangement and meat quality in slaughter descendants Cow Herd Small to direct size Adapted to atmosphere Optimal drain creation for sustain assets Progeny Maximize top notch incline hamburger delivered per unit nourish devoured by offspring and cow group

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Rotational and Terminal Sire Crossbreeding Programs Two Breed Composite Cow Age No. 1 20 2 18 3 15 2 Breed 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%

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Weaning Wt Marketed Per Cow Exposed for Alternative Crossbreeding Systems Relative to Straightbreeding (%) Wean. wt Terminal H i H m advertised cross a System + 8.5% +14.8% per bovine exp (+5% wt/calf) Straight breeding 0 0 0 0 2-breed turn (A,B) .67 .67 15.5 20.8 3-breed revolution (A,B,C) .86 .86 20.0 24.1 4-breed pivot (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 pivot (3-breed: AB, AC) .67 .67 15.5 20.8 F1 bull pivot (4-breed: AB, CD) .83 .83 19.3 23.6 an Assumes 66 % of calves promoted (cows and yearlings) are by terminal sire breed out of more develop age dams and 33% are by maternal breeds (controls as it were).

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SUMMARY

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General Considerations Rotational Systems Provide for more powerful utilization of Heterosis Composite populaces Provide for more successful utilization of Breed contrasts Uniformity and final result consistency

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Figure 6. Utilization of heterosis, added substance breed impacts and Complementarity with option crossbreeding frameworks.

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Implications for Crossbreeding Advantages of terminal sire crossing frameworks are not as incredible today as 30 years back because of comparability of breeds for rate and effectiveness of development. Nonetheless, contrasts amongst British and Continental breeds in cadaver qualities are still critical and moderately vast. Entomb era changes in mean execution for remains qualities are still extensive and noteworthy. For remains characteristics, consistency and final result consistency can in any case be upgraded by utilization of composite populaces or half breed bulls. Adjustment to moderate subtropical/calm situations can be improved with more prominent exactness by utilization of composite populaces or half breed bulls.

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Module IV Applied Animal Breeding and Selection Homework questions relegated September 18 To be returned by October 23, 2008 (Email to: larry.cundiff@ars.usda.gov ) The Brangus breed has a hereditary arrangement of 5/8 Angus and 3/8 Brahman reproducing. 1) What is the normal heterozygosity or level of Brahman X Angus heterosis expected in the Brangus breed (indicate work)? 2) How might you expect the impact of heterosis for Brangus to contrast with that in a breed with a piece of 5/8 Angus and 3/8 Shorthorn, why or why not? (As such, would impacts of heterosis be the same, or more, or less for Brahman X Angus crosses than for Angus X Shorthorn crosses, why or why not?) 3) What is the normal level of heterosis in a four breed composite established with ¼ breed A, ¼ breed B, ¼ breed C, and ¼ breed D legacy (demonstrate work)? 4) S t

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