Systems of Crossbreeding – Experiences in Research &

Do’s and Don’tsR. Mark Enns

Colorado State University

Overview

• Crossbreeding systems

• Research experience and recommendations

Factors to consider when selecting a system

• Amount of hybrid vigor– Two types

• Individual– For weaning weight – 5%– For weaning rate – 0%

• Maternal– For weaning weight – 6%– For weaning rate – 8%

– Total• Weaning wt per cow exposed – 18%

Kress and MacNeil, 1999

Factors to consider when selecting a system

• Amount of hybrid vigor– Two types

• Individual• Maternal

• Breed complementarity• Consistency of product• Replacement generation – males and females• Simplicity of the system

– Dr. Gosey calls “management ease” test• Accuracy of evaluation

– In the future?

• Assumption: Have appropriately selected the breeds to go into the system

Bourdon, 2000

The Key

Find a system that is beneficial for the specific production situation and whose downside is relatively minor.

Examples

3 breed spatial rotation

A higher proportionBreed B

A higher proportionBreed C

X

Breed C Breed A

X

A higher proportionBreed A

Breed B

X

Replacement

ReplacementReplacement

Attributes

• Hybrid vigor Increased hybrid vigor

• Breed

Complementarity potential

• Consistency inversely related to complementarity

Attributes

• Replacements yes

• Genetic evaluation likely

• Simplicity low

3-Breed Rotation in Time

Most females a higher proportion Breeds B and C

X Breed A

Most females a higher proportion Breeds C and A

X Breed B

Most females a higher proportion Breeds A and B

X Breed C

Most females a higher proportion Breeds B and C

X Breed A

Time

Replacement and remaining older females

Replacement and remaining older females

Replacement and remaining older females

Attributes of Rotations in Time

• Hybrid Vigor--somewhat reduced

• Breed complementarity, consistency of performance, replacement considerations, and accuracy of genetic prediction

• Simplicity – greatly increased

Rotations in time designed for small producers

Weakness: Consistency of decisions over time

Terminal Sire Systems

• Maternal-breed females are mated to paternal-breed sires

• Goal: to efficiently produce progeny that are especially marketable

Static Terminal System

Purchased F1 AxB maternalfemales

Breed Cterminal

X

F1 C x (A x B) market offspring

Key

• Consider the factors that are most important to the producer– Give the program the greatest probability

of success

Comparison of systems

Crossbreeding System HV Comp Const Ease ACC

Spatial Rotation + - Varies Varies +

Rotation in Time + - varies ++ +

Terminal system (purchase replacement ♀) ++ ++ + ++ +

Composite system (already formed) + + + ++ +

• Assumption: All of the above produce their own replacement females except the terminal system

Bourdon, 2000

Numerous other systems

Only limited by the breeder’s creativity

Rotation/Terminal Systems

X

A higher proportionBreed B

A higher proportionBreed A

X

Breed ABreed BReplacement

Replacement

Excess (often older) females

Male offspringsold

Male offspringsold

F1 C x (A/B) market offspring

Composite/Terminal System

Younger maternalcomposite females

X Maternalcomposite

Older maternalcomposite females

X Terminal Breed

F1 market offspring

Male offspringsold

More systems than can be outlined in a hour

Research – Do’s and Don’ts

• Heterosis will not overcome poor breed choice– Advantage of Zebu cross dams in Florida for pregnancy rate

was 5.8% units over that in Nebraska (1.8% units)• Olson et al., 1991

– Holstein Hereford cross had a 23% advantage over HA for calf weaned/cow-exposed, and Brahman cross a 13% advantage (Setshwaelo et al., 1990)

• Cross must be appropriate for its production environment– Drs. Kress and Franke will discuss next week.

• Continous use of the same breed will result in loss of heterosis– Dr. Gosey

• 3 generations of using Angus bulls on F1 cows resulted in a loss of 87% of hybrid vigor

Crossbreeding works

• Increases in lifetime production due to maternal heterosis have been estimated at up to 1.44 calves when calving first as 2 year olds (Cundiff et al., 1992) defined as cumulative 200 day weight

• Nunez et al., (1991) crossbred cows had lower probabilities of being culled than straightbreds (Angus, Hereford, Shorthorns)

• Davis et al. (1994) reported F1 cows averaged 1.2 year longer lifespan than straightbred cows– Net profit per cow exposed increased ~$75

Do not be tempted to retain replacement females from terminal sire mating

systems in restrictive environments

Energy consumed to produce calf weight varies between breeds– Jenkins et al. (1991)

• In most environments– At low to moderate resource availability the

British breeds tend to be most efficient at converting intake into calf weight

– At higher levels of availability (intake) the continental breed tend be the most efficient

• Jenkins et al. (1994)

Develop a plan and stick to it, otherwise …

• Using Dr. Gosey’s example– 15/16 Angus

• Realized that have lost heterosis, so go back to Hereford bulls– Use bulls for 3 years and 15% female

replacement rate, 1 year after last crop born• 38% of females are now F1• 62% of females are still Angus

• 38% are now F1 and 62% are still Angus– So switch to a 3rd breed for 3 years

• A year after the last crop is born– 24 % are HxA– 38% are Angus– 39% are new cross

• Point:– Without a plan and some determination to

maintain focus• can get quite the collection of different breeds• Influences marketability

Choose not only breeds but appropriate animals within breeds

• Colorado State University experience– Generalization:

• Black baldy cows are adapted to the eastern Colorado shortgrass prairies

– Can we identify another genotype that might be adapted to that environment but bring more performance in the feedlot and on the rail?

Approach

• Given: Hereford x Angus cross works well– Choose a breed from which we could find

animals with similar milk production levels– Continental breed

Approach

• Given Hereford Angus cross works well– Choose a breed from which we could find

animals with similar milk production levels– Continental breed

• Limousin

– HxA and LxA females

EPD Guidelines

BW YW Milk

Hereford ≤ 2.0 60 to 70 8 to 15

Percentiles 20% 55% to 30% 80% to 45%

On NALF Scale ≤ 1.6 77 to 87 7.6 to 14.6

2003 Calves No. WW Calf Age

Adj WW

Hereford x Angus

23 498 195 521

Lim-Flex 27 510 195 531

2003 Calves No. WW Calf Age

Adj WW

Hereford x Angus

23 498 195 521

Lim-Flex 27 510 195 531

2004 Calves No. WW Calf Age Adj WW

Hereford x Angus

67 409 156 520

LimFlex 14 456 188 502

No. Weight

Frame

Score

Hereford x Angus 28 704 4.7

Lim-Flex 33 685 5.2

Difference 19 -.5

• Yearling performance–Weight and Frame Score

Weight FSPelvic Area

Hereford x Angus 704 4.7 168

Lim-Flex 685 5.2 169

Difference 19 -.5 -1

• Yearling performance

% Bred 1st

21days

Total

% Bred % Open

Hereford x Angus

71 93 7

Lim-Flex 61 79 21

Difference 10 14 -14

• Breeding performance–60 Day breeding season

• After 1st calf, all rebred except 1

• Although preliminary, we believe we may have another adapted F1 cross appropriate to the eastern Colorado environment

Breed AveragesLimFlexCW – 793REA – 12.44YG – 3.27(2.6)YG4 – 0%CAB – 40%$/cwt - $146.11

Last 83 daysAvg Daily Intake – 30.0ADG – 3.06

$/hd – $1159.20

Angus

CW – 762

REA – 12.14

YG – 3.45(3.4)

YG4 – 40%

CAB – 20%

$/cwt - $137.90

Avg Daily Intake – 31.7

ADG – 3.79

$/hd – $1050.57

Do’s and Don’ts

• Choose a system that has a high probability of success– simplicity

• Make appropriate breed choice• Make appropriate choice from within breed• Stick to the plan to avoid “mongrelization”• Commercial producers should crossbreed

R. Mark EnnsDept. of Animal SciencesColorado State University

Fort Collins, CO 80523

Phone: 970-491-2722

Email: mark.enns@colostate.edu