Title: Selection For Carcass Marbling and Muscling-- Benefits and Pitfalls
1Selection For Carcass Marbling and Muscling--
Benefits and Pitfalls
- Jim Gosey University of Nebraska
2Heritability of Reproduction Traits
- about 20
- Conception rate
- Calving rate
- Calving ease
-
-
3Heritability of Production Traits
- about 30 to 35
- Birth , Wean, Year. Wts.
- Feed Intake
- Feed Conversion
- Mature Wt. 50
4Heritability of Product Traits
- about 40
- Fat
- REA
- Cutabilty
- Marbling
- Shear ?
5- Highly heritable traits are usually best changed
by direct selection.. - Lowly heritable traits are usually best changed
by crossbreeding ( heterosis and complementarity)
6Carcass Traits can be changedGenetically.
- Angus genetic trends for slaughter and
ultrasound data indicate breeders have changed
carcass traits !
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13Heritability and Genetic Correlation--Slaughter
Data
- Trait Wt. Marb. REA Fat
RP - Weight (Wt) .30 -.02 .52 .13
-.14 - Marbling (Marb.) .36 -.09 .09
-.11 - Ribeye (REA) .28 -.22
.59 - Fat Thick. (Fat) .25
-.85 - Ret.Prod. (RP)
.25 - 71,273 Angus records, Fall 2003
14Heritability and Genetic Correlation--Ultrasound
Data
- Trait Wt. IMF REA Fat
RP - Weight (Wt) .57 -.07 .40 .18
-.19 - IMFat (IMF) .31 -.04 .22
-.16 - Ribeye (REA) .38 .18
.59 - Fat Thick. (Fat) .39
-.49 - Ret.Prod. (RP)
.39 - 294,515 Angus records, Fall 2003
15- 1. Heritabilities higher for Ultrasound
- 2. Selection for Marbling (IMF) will
- decrease Ribeye (-.09) (-.04)
- increase Fat (.09) (.22)
- decrease Ret. Prod. (-.11) (-.16)
- 3. Selection for Ribeye will
- increase Ret Prod. (.59) (.59)
- change Fat (-.22) or (.18)
16Selection to change Net Carcass Merit will
require selection for both Marbling(IMF) and
Ribeye area
- Genetic Correlation between Marbling (IMF) and
Ribeye is low enough to allow simultaneous change
in both traits.
17Summaries of research data have produced higher
genetic correlations than breed carcass data
18Antagonistic Genetic Correlations
- Calving ease Birth wt. -.74
- Marbling Cutability -.25
- Marbling Year. wt. -.33
- Marbling REA -.21
- Marbling Backfat .35
- Marbling Shear Force -.31 ?
- Koots, 1994
19Genetic Correlations Between Reproduction
Product Traits
- Female Fat Retail
- Trait Trim WT. Product Wt.
- Age Puberty -.29 .30
- Concept./Service .21 .28
- Calv. Difficulty -.31 -.02
- Birth Wt. -.07
.30 - Mature Wt. -.09 .25
- MacNeil, 1984
20Carcass EPD of Sort Group(3sd) - Slaughter
Data
- Group Marb. REA Fat RP YW Milk
- Angus Av. .14 .09 .003 .03 65
17 - Marbling(46) .68 .20 .003 .18 66
21 - REA (32) .12 .61 -.017 .67 76
20 - 4,051 Current Angus sires, Fall 2003
- number of bulls in ( )
21Carcass EPD of Sort Group(3sd) - Ultrasound
Data
- Group IMF REA Fat RP YW Milk
- Angus Av. .05 .07 .00 -.01 65
17 - IMF (37) .50 .14 .02 -.04 72
21 - REA (32) .08 .74 .00 .58 88
20 - 4,051 Current Angus sires, Fall 2003
- number of bulls in ( )
22Outlier bulls for Marbling tended to be..
- Above average for Milk and Ribeye
- Mixed result for Fat
- Retail Product
23Outlier bulls for Ribeye tended to be.
- Average for Marbling (IMF)
- Above average for Retail Product, Yearling Wt.
and Milk
24Number of Outlier Bulls for Marbling and Ribeye
- Trait 1sd 2sd
3sd - Marb REA 164 22 4
- Marb REA (.50acc) 140 22 4
- 4,051 Current Angus sires, Fall 2003
25Multiple trait selection slows response in any
one trait...
- How many Angus bulls are above average for
Marbling, Ribeye, Wean Wt., Year. Wt., SC,
below average for Birth Wt. ? - 32 out of 3,172
- 1 Std. Dev. 10 bulls
- 2 Std. Dev. 0 bulls
26What about Marbling and Tenderness ?
- 102 Simmental bulls with progeny Tenderness data.
- Tender 10 bulls .16 Marb. EPD
- Simm. Average .09 Marb. EPD
- Tough 10 bulls .03 Marb. EPD
- Marbling is a crude predictor of tenderness, not
a guarantee
27DNA Testing to the Rescue ?
- DNA tests for the Marbling gene and the
Tenderness gene only account for a small
portion of the genetic variation (perhaps 10-15).
28Benefits of selection for Marbling / Muscling
- 1. Marbling alone faster change
- 2. Muscling alone faster change
- 3. Marbling and Muscling check and balance,
slows increases, reduces non-conforming cattle
29Pitfalls of selection for Marbling / Muscling
- 1. Marbling risk too much milk
- Tenderness more important
- 2. Muscling
- risk too much mature size
- risk too much birth wt.
- risk lowered fertility
30Summary
- 1. Marbling Muscle respond
- 2. Outlier balance trait bulls scarce
- 3. Ultrasound database increases
- 4. DNA tests to screen seedstock
- 5. Threshold marbling important
- 6. Crossbreeding can help solve genetic
antagonisms