Crossbred or Composite Seedstock,

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Crossbred or Composite Seedstock, What are the
Opportunities
Larry V. Cundiff MARC-ARS-USDA Clay Center, NE
American Simmental Association Seminar BIF Annual
Meeting Choctaw, MS April 18, 2006
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BREED DIFFERENCES an important genetic resource

• Cross breeding or 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

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Heterosis
Weight of Calf Weaned Per Cow Exposed To Breeding
23.3

• Heterosis increased 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
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HETEROSIS

• Increased herd life per cow 1.36 yr or 16.2.
  
• Increased life time production of calf wt
  weaned
• 600 lb or 25.3.
• Reduced break even cost of production about
  9.5.

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Rotational Crossbreeding Systems
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HETEROSIS EFFECTS AND RETAINED HETEROSISIN
COMPOSITE POPULATIONS VERSUS CONTRIBUTINGPUREBRED
S (Gregory et al., 1992)
Composites minus purebreds
Trait F1 F2 F34
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
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Composite populations maintain
heterosisproportional to heterozygosity(n-1)/n
or 1 S Pi2
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MODEL FOR HETEROZYGOSITY IN A TWO BREED COMPOSITE
Breed Breed of sire Dam ½ A ½ B ½ A
AA AB ½ B BA BB
(n-1)/n or 1 S Pi2 .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 Pi2 (1 - .375) .625
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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
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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).
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Heterosis Retention in Bos taurus X Bos indicus
Results are mixed Consistent with dominance
model (B x H, P, backcross, F1 ,
F2) Cartwright et al., (1964) (B x A,
backcross) Turner and MacDonald (1969) (B x Sh,
rotations) Koger et al., 1975 (B x A, B x C,
backcrosses) Peacock and Koger (1979) (B x H,
P, F1 , F2) Sanders et al. (2005) Not
consistent with dominance model (B x H,
backcrosses) Arthur et al. (1999) (B x A, P, F1
, F2) Sanders et al. (2005)
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Matching Genetic Potential to the Climatic
Environment (Olson et al., 1991)
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• Composite populations provide for effective use
  of
• Heterosis
• Breed differences
• Uniformity and end product consistency

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COEFFICIENTS 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
puberty (females) .08 .07 Scrotal
circumference .07 .07 5 yr cow wt, lb .07 .08 5
yr height, in .02 .02 Steer carcass wt,
lb .08 .08 Rib-eye area .10 .10 Retail product,
.04 .06 Retail product, lb .19 .20
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Breed differences for growth traits are not as
great today as 30 years ago
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SIRE BREED MEANS FOR FINAL WEIGHT AND CARCASS
TRAITS OF F1 STEERS WITH HEREFORD, ANGUS, OR
MARC III DAMS (445 DAYS)
Final Retail Marb- USDA WB Sire wt
product ling Choice shear Breed N lb
lb sc lb
Hereford 97 1322 60.7 480 526 70 9.1 Angus 98 1365
59.2 488 584 95 8.9 Red Angus 93 1333 59.1 474 59
0 93 9.2 Simmental 92 1363 63.0 522 528 66 9.5 Ge
lbvieh 90 1312 63.8 509 506 58 9.9 Limousin 84 128
6 63.7 504 504 57 9.5 Charolais 95 1349 63.7 523 5
17 62 9.6 LSD lt .05 40 1.3 16 17 0.7 0.6
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• Sire breed differences in reproduction rate and
  calf survival to weaning not significant.
• Contrasts between British (H and A) and
  Continental European breeds (S, G, L, and C) are
  about 1/4th as great for direct (5.5 vs 22 lb)
  and 4/10th as great for maternal (10 vs. 24 lb)
  breed effects in the current evaluation as they
  were to 30 years ago.

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SIRE BREED MEANS FOR HEIGHT, CONDITION SCORE,
WEIGHT AND WEIGHT ADJUSTED FOR CONDITION SCORE
AT 5 YEARS OF AGE

Act.
Adj.
Height Condition Weight
Weighta Breed No.
cm score lb
lb
Hereford 56 135.4 7.0 1496
1419 Angus 62 134.4 7.2 1501 1411 Red
Angus 68 134.4 7.4 1510 1409 Simmental 70 137.4
7.0 1476 1406 Gelbvieh 68 135.0 6.8 1381 1323 Lim
ousin 80 137.4 6.9 1462 1393 Charolais 69 137.4 7
.1 1474 1372 LSD lt .05 0.8 0.3 64 57
a Adjusted to condition score of 5.5
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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.

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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.
• Inter generation fluctuations in mean
  performance for carcass traits are still large
  and significant.

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Implications for Crossbreeding

• Rotational Systems
• Provide for more effective use of
• Heterosis
• Composite populations
• Provide for more effective use of
• Breed differences
• Uniformity and end product consistency

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F1 BULLS or COMPOSITE BULLS

• In general, they are not very different
• With only 2 breeds, for commercial customers
• F1 bulls Composite bulls
• With multi-breed EPDs, selection can be equally
  effective
• Adjustments in breed composition and breeding
  value for specific traits can be made more
  rapidly producing F1 bulls than in composite
  populations.

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F1 BULLS or COMPOSITE BULLS

• In composite populations, with additional
  foundation breeds
• Breed effects can be optimized with greater
  precision.
• Heterosis effects can be increased to more nearly
  competitive levels.
• Mating plans are less complex for the commercial
  customer.
• Seedstock producer benefits from heterosis.

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Will terminal crossing decrease or increase?
Complementarity
is maximized in terminal crossing systems
Cow Herd Small to moderate
size Adapted to climate Optimal milk production
for feed resources
Terminal Sire Breed Rapid and efficient
growth Optimizes carcass composition and meat
quality in slaughter progeny
Progeny Maximize high quality
lean beef produced per unit feed consumed by
progeny and cow herd
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Weaning Wt Marketed Per Cow Exposed for
Alternative Crossbreeding Systems Relative to
Straightbreeding ()

Wean. wt
H i
Hm marketed
Comple- System
8.5 14.8 per cow exp mentarity
Straight breeding 0 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
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EPDs from 2006 genetic evaluations for bulls used
in Cycles I II (1970-74), and Cycle VII
(1999-2000) compared to current (2004) breed
average
Breed BWT WNWT YRWT
MILK III VII Avg III VII Avg III
VII Avg III VII Avg.
Angus -1.2 1.6 2.3 2.3 33.8 38.5 2.8 68.3 71.5
0.4 21.4 19.0 Hereford -.4 3.0
3.7 4.1 37.2 37.0 3.8 64.6 63.0 2.0 15.2 14.0 Red
Angus -- -0.7 .4 -- 27.7 29.0 -- 48.3 51.0 -- 13.
9 15.0 Simmental 2.9 2.0 1.8 18.5 37.0 34.1 28.9
65.3 59.5 8.8 5.1 5.4 Gelbvieh 2.4 0.7
1.9 30.8 36.7 41.0 52.8 69.4 73.0 16.2 19.3 18.0
Charolais 0.3 0.3 1.3 0.5 21.9 20.0 0.5 40.1 35.
2 0.3 10.1 6.2 Limousin -0.1 2.0
2.1 12.0 35.7 36.3 27.0 70.5 68.2 16.9 15.4 18.3