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Marbling score: Difference between revisions

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[[Category:Carcass Traits]]
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     Place brief trait definition/description here  
     Place brief trait definition/description here  
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===Phenotype===
<!-- Describe ways the phenotype is collected  
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     E.g., for birth weight discuss digital scale, mechanical scale, hoof tape, etc.
     E.g., for birth weight discuss digital scale, mechanical scale, hoof tape, etc.
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Marbling, the  flecks  of  fat  in  the  lean,  is  the  primary  factor  determining  quality  grade after maturity has been determined.  Marbling is evaluated either visually or using cameras in the ribeye muscle, which  is  exposed  between  the  12th and 13th ribs.  Marbling score values are used in determine the [[Quality Grade#Marbling | quality grade]] of a caracass.
===Phenotype===
{| class="wikitable" style="margin: auto;"
!colspan="6"|'''Numerical Scores for USDA Quality Grades and corresponding Marbling Scores*'''
|-
|'''Quality Grade'''
|'''Marbling'''
|'''Score'''
|-
|Prime
|Abundant
|9.0 – 9.9
|-
|Prime
|Moderately Abundant
|8.0 – 8.9
|-
|Prime
|Slightly Abundant
|7.0 – 7.9
|-
|Choice
|Moderate
|6.0 – 6.9
|-
|Choice
|Modest
|5.0 – 5.9
|-
|Choice
|Small
|4.0 – 4.9
|-
|Select
|Slight
|3.0 – 3.9
|-
|Standard
|Traces
|2.0 – 2.9
|-
|Standard
|Practically devoid
|1.0 – 1.9
|}
<div style="text-align: center;">*These values were changed on February 7, 2022 to correspond with the numeric scores used by USDA.
<div style="text-align: left;">Relationships between marbling scores and intramuscular fat percentages are shown below:
{| class="wikitable" style="margin: auto;"
!colspan="6"|'''Marbling and Intramuscular Fat'''
|-
|'''Marbling Score'''
|'''Intramuscular Fat, %'''
|-
|Slightly Abundant
|10.13
|-
|Moderate
|7.25
|-
|Modest
|6.72
|-
|Small
|5.04
|-
|Slight
|3.83
|-
|Traces
|2.76
|}


===Adjusted Value===
===Adjusted Value===
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     If the trait is not adjusted (e.g. Stayability) then say so
     If the trait is not adjusted (e.g. Stayability) then say so
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Marbling score is then reported on an age-constant basis
Marbling score is then reported on an age-constant basis.


===Contemporary Group===
===Contemporary Group===
<!-- Discuss how contemporary groups are formed -->
<!-- Discuss how contemporary groups are formed -->
A contemporary test group is a set of cattle of the same sex that have been raised together and have received equal treatment up to the point  of  slaughter.    All  progeny  within  a  contemporary  group  should  be  born within  a  90-day  period,  and  male  calves  must  be  castrated prior  to  150  days  of age.  A contemporary group up to the time of weaning will be subdivided if some cattle go on feed as calves and others are started on feed as yearlings, and if the cattle  are  then  split  into two  or  more  slaughter  groups.  Birth date, identification of sire and dam,  breed  of  dam  (or  breed  proportions  in  crossbred  dams) should be recorded for all individuals.
A contemporary group is a set of cattle of the same sex that have been raised together and have received equal treatment up to the point  of  slaughter.    All  progeny  within  a  contemporary  group  should  ideally be  born within  a  90-day  period,  and  male  calves  must  be  castrated.  A contemporary group up to the time of weaning will be subdivided if some cattle go on feed as calves and others are started on feed as yearlings, and if the cattle  are  then  split  into two  or  more  slaughter  groups.  Birth date, identification of sire and dam,  breed  of  dam  (or  breed  proportions  in  crossbred  dams) should be recorded for all individuals.


===Genetic Evaluation===
===Genetic Evaluation===
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     Discuss in what circumstances the trait is an ERT or an indicator trait and how the trait should be used and not used.
     Discuss in what circumstances the trait is an ERT or an indicator trait and how the trait should be used and not used.
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Although producers are paid for improved quality grade, marbling score is generally considered an economically relevant trait. Producers can use marbling score EPD to improve the quality grade of fed cattle. Ideally this would be done through the use of a more comprehensive economic selection index that takes into account other revenue traits as well as traits related to the cost of production.

Latest revision as of 16:51, 7 February 2022


Marbling, the flecks of fat in the lean, is the primary factor determining quality grade after maturity has been determined. Marbling is evaluated either visually or using cameras in the ribeye muscle, which is exposed between the 12th and 13th ribs. Marbling score values are used in determine the quality grade of a caracass.

Phenotype

Numerical Scores for USDA Quality Grades and corresponding Marbling Scores*
Quality Grade Marbling Score
Prime Abundant 9.0 – 9.9
Prime Moderately Abundant 8.0 – 8.9
Prime Slightly Abundant 7.0 – 7.9
Choice Moderate 6.0 – 6.9
Choice Modest 5.0 – 5.9
Choice Small 4.0 – 4.9
Select Slight 3.0 – 3.9
Standard Traces 2.0 – 2.9
Standard Practically devoid 1.0 – 1.9
*These values were changed on February 7, 2022 to correspond with the numeric scores used by USDA.


Relationships between marbling scores and intramuscular fat percentages are shown below:
Marbling and Intramuscular Fat
Marbling Score Intramuscular Fat, %
Slightly Abundant 10.13
Moderate 7.25
Modest 6.72
Small 5.04
Slight 3.83
Traces 2.76

Adjusted Value

Marbling score is then reported on an age-constant basis.

Contemporary Group

A contemporary group is a set of cattle of the same sex that have been raised together and have received equal treatment up to the point of slaughter. All progeny within a contemporary group should ideally be born within a 90-day period, and male calves must be castrated. A contemporary group up to the time of weaning will be subdivided if some cattle go on feed as calves and others are started on feed as yearlings, and if the cattle are then split into two or more slaughter groups. Birth date, identification of sire and dam, breed of dam (or breed proportions in crossbred dams) should be recorded for all individuals.

Genetic Evaluation

Marbling score is generally included in a multiple-trait model along with its ultrasound indicator and other carcass-fat-related traits (e.g., back fat and ultrasound back fat). An early growth trait (e.g., birth or weaning weight) may also be included to account for sequential culling if the genetic covariance is sufficient. Only direct genetic effects are fitted.

Usage

Although producers are paid for improved quality grade, marbling score is generally considered an economically relevant trait. Producers can use marbling score EPD to improve the quality grade of fed cattle. Ideally this would be done through the use of a more comprehensive economic selection index that takes into account other revenue traits as well as traits related to the cost of production.

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