animal
Animal (2008), 2:5, pp 752–760 & The Animal Consortium 2008
doi: 10.1017/S1751731108001754
The value of muscular and skeletal scores in the live animal and
carcass classification scores as indicators of carcass composition
in cattle
M. J. Drennan-, M. McGee and M. G. Keane
Teagasc, Grange Beef Research Centre, Dunsany, Co. Meath, Ireland
(Received 17 May 2007; Accepted 24 January 2008)
The objective was to determine the relationship of muscular and skeletal scores taken on the live animal and carcass conformation
and fat scores with carcass composition and value. Bulls (n 5 48) and heifers (n 5 37) of 0.75 to 1.0 late-maturing breed
genotypes slaughtered at 16 and 20 months of age, respectively, were used. At 8 months of age (weaning) and immediately
pre-slaughter, visual muscular scores were recorded for each animal and additionally skeletal scores were recorded pre-slaughter.
Carcass weight, kidney and channel fat weight, carcass conformation and fat scores, fat depth over the longissimus dorsi
muscle at the 12th (bulls) or 10th (heifers) rib and carcass length were recorded post-slaughter. Each carcass was subsequently
dissected into meat, fat and bone using a commercial dissection procedure. Muscular scores taken pre-slaughter showed positive
correlations with killing-out rate (r E 0.65), carcass meat proportion (r E 0.60), value (r E 0.55) and conformation score
(r E 0.70), and negative correlations with carcass bone (r E 20.60) and fat (r E 20.4) proportions. Corresponding correlations
with muscular scores at weaning were lower. Correlations of skeletal scores taken pre-slaughter, carcass length and carcass
weight with killing-out rate and the various carcass traits were mainly not significant. Carcass fat depth and kidney and channel
fat weight were negatively correlated with carcass meat proportion and value, and positively correlated with fat proportion.
Correlations of carcass conformation score were positive (r 5 0.50 to 0.68) with killing-out rate, carcass meat proportion and
carcass value and negative with bone (r E 20.56) and fat (r E 20.40) proportions. Corresponding correlations with carcass
fat score were mainly negative except for carcass fat proportion (r E 0.79). A one-unit (scale 1 to 15) increase in carcass
conformation score increased carcass meat proportion by 8.9 and 8.1 g/kg, decreased fat proportion by 4.0 and 2.9 g/kg and
decreased bone proportion by 4.9 and 5.2 g/kg in bulls and heifers, respectively. Corresponding values per unit increase in carcass
fat score were 211.9 and 29.7 g/kg, 12.4 and 9.9 g/kg, and 20.5 and 20.2 g/kg. Carcass conformation and fat scores explained
0.70 and 0.55 of the total variation in meat yield for bulls and heifers, respectively. It is concluded that live animal muscular
scores, and carcass conformation and fat scores, are useful indicators of carcass meat proportion and value.
Keywords: beef, carcass conformation score, carcass classification, muscular scores
Introduction
For those involved in beef cattle genetic improvement
programmes, producers and processors, estimates of meat
yield, meat distribution in the carcass (due to the differences in value between cuts), and ideally carcass value
based on meat yield and distribution, is desirable. Accurate
prediction of carcass value or quality based on body composition would enable the early selection of efficient
animals by beef producers as well as seedstock breeders
(Afolayan et al., 2007). Live-animal indicators of carcass
-
E-mail: [email protected]
meat yield and distribution include visual muscular and
skeletal scores, whereas carcass indicators are conformation
and fat scores. Carcass merit of animals in pedigree beef
herds, which are destined for breeding, is dependent on
having information on the relationship between measurements and scores taken on the live-animal and carcass meat
yield and value. Data collected at present by breed societies
and others involved in beef improvement programmes
include muscular and skeletal scores, and scanned longissimus muscle size and fat cover. In the European Union
(EU), data recorded for beef carcasses include scores for
conformation (EUROP scale with E best for conformation)
and fatness (scale 1 to 5, with 5 fattest), gender category
752
Downloaded from https:/www.cambridge.org/core. IP address: 88.99.165.207, on 16 Jun 2017 at 19:31:54, subject to the Cambridge Core terms of use, available at
https:/www.cambridge.org/core/terms. https://doi.org/10.1017/S1751731108001754
Value of muscular and skeletal scores as indicators of carcass composition in cattle
(steer, heifer, young bull, cow, bull) and carcass weight.
Conformation and fatness are based on visual examination
of carcasses (Commission of the European Communities,
1982), which, since this study was carried out, has been
replaced by mechanical classification in Ireland (Allen
and Finnerty, 2000). In the EU, payment for carcasses within
each gender category is based mainly on carcass scores,
payment for which can differ substantially between countries particularly, for conformation. It is therefore desirable
to acquire information on the effect of classification scores
on meat yield and distribution. Such information, in addition
to being useful for pricing purposes, can be used in beef
improvement programmes where progeny are identified and
classified at slaughter.
Tatum et al. (1986) showed that a subjective score for
muscle thickness on the live animal was significantly
associated with meat yield. Similarly, Perry et al. (1993a)
reported a correlation of 0.70 between saleable meat and
muscle score on the live animal. Afolayan et al. (2002)
showed that prediction equations, using objective measurements recorded on the live animal, accounted for 56%,
56% and 39% of the variation in carcass meat, fat and
bone proportions, respectively. Kauffman et al. (1973) found
that animal or carcass shape was a significant factor in
determining carcass composition, but its role was minor
compared with carcass fatness. They concluded that the
importance of muscularity may be overlooked when carcass
composition is determined by techniques such as specific
gravity or proportion of trimmed wholesale or retail cuts in
which bone was not removed, and thus permitted to
influence the net result. Earlier studies showed that carcass
conformation score (shape due to muscle and fat layers)
was of little value as an indictor of meat yield but that fatcorrected conformation score was valuable in commercial
classification schemes (Kempster and Harrington, 1980;
Kempster, 1986). Perry et al. (1993b) reported that carcass
weight alone, carcass weight with carcass muscle score,
and carcass weight with carcass muscle and fat scores
accounted for 0.1%, 37.9% and 46.7%, respectively, of the
total variation in saleable meat yield. Despite the widespread use of live-animal scoring in breeding programmes
and the use of the EU carcass classification grid for pricing,
there are few data showing the relationship of those with
carcass meat yield and value.
The objective of the present study was to examine the
relationships of live-animal visual muscular and skeletal
scores, carcass weight and length, carcass fat depth over
the longissimus dorsi muscle, and carcass conformation and
fat scores, with killing-out rate, carcass composition and
estimated carcass value of bulls and heifers.
Materials and methods
Animals and management
In all, 48 bulls and 37 heifers were used in the study.
The animals were the progeny of late-maturing purebred (Charolais and Limousin) or crossbred [Limousin 3
Friesian, Limousin 3 (Limousin 3 Friesian) and Simmental 3
(Limousin 3 Friesian)] beef suckler cow genotypes. Forty
bulls and all of the heifers were the progeny of one
Limousin sire, whereas the remaining eight bulls were the
progeny of a Charolais sire. The animals used represent a
major segment of the progeny from the Irish beef cow herd,
which comprises 51% of total cows where 71% are latematuring breed crosses and 86% are bred to late-maturing
sire breeds (CMMS, 2006). The animals were born in spring,
spent the summer at pasture with their dams and were
weaned at an average of 8 months of age. The bulls spent
the subsequent 218 days indoors during which they were
offered a diet based on well-preserved, high nutritive value
grass silage (pH 3.7, dry matter (DM) 197 g/kg, crude protein (CP) 144 g/kg, in vitro dry matter digestibility (IVDMD)
774 g/kg) ad libitum and an average of 4.0 kg per head
daily of a barley-based concentrate supplement. Daily
liveweight gains of the bulls pre- and post-weaning averaged 1.00 and 1.19 kg/day, respectively. They were slaughtered at an average age of 458 days. Forty were slaughtered
on the same day and the remaining eight 7 days later. The
heifers were offered the same grass silage as the bulls plus
1 kg of concentrate daily during the 5-month winter following weaning after which they spent a second season at
pasture. They received an average of 3.3 kg of concentrates
per head daily during the last 84 days before slaughter
and grazed grass was replaced with grass silage (pH 3.8,
DM 163 g/kg, CP 155 g/kg, IVDMD 713 g/kg) for the final
36 days. Daily liveweight gains of the heifers pre- and
post-weaning were 0.88 and 0.67 kg/day, respectively. All
were slaughtered on the same day at an average age of
612 days. Final liveweights were the mean of unfasted
weights taken on two mornings before slaughter. All
animals were slaughtered in the same commercial abattoir.
Live animal scores
Visual muscular scores were assigned to each animal using
both the Irish Cattle Breeding Federation (ICBF) and Signet
scoring (Collins, 1998) procedures at weaning and prior to
slaughter. The ICBF system (ICBF linear scoring reference
guide, 2002) involved assigning muscular scores (scale 1 to
15) at nine locations: (1) width at withers, (2) width behind
withers, (3) thigh width, (4) development of hind quarters,
(5) thickness of loin, (6) development of inner thigh, (7) loin
width, (8) rump width and (9) thigh depth). Two trained
Assessors from ICBF (A and B) scored the animals at
slaughter but only Assessor A scored them at weaning. In
the Signet procedure, muscular scores (scale 1 to 15) were
assigned at three locations (roundness of hindquarter, width
of rump and width and thickness of the loin) using two
experienced Assessors (C and D) from the research centre
on each occasion. For each Assessor the scores at the
different locations were averaged to give one value for each
animal at weaning and prior to slaughter. In addition,
prior to slaughter all animals were assigned skeletal scores
(scale 1 to 10) at three locations (length of back, pelvic
length and height at withers) by the ICBF Assessors.
753
Downloaded from https:/www.cambridge.org/core. IP address: 88.99.165.207, on 16 Jun 2017 at 19:31:54, subject to the Cambridge Core terms of use, available at
https:/www.cambridge.org/core/terms. https://doi.org/10.1017/S1751731108001754
Drennan, McGee and Keane
Slaughter and carcass records
Hot carcass weight and weight of kidney plus channel fat
were recorded at slaughter. Cold weight was taken as 0.98
hot carcass weight. Carcasses were visually classified
according to the EU Beef Carcass Classification Scheme
(Commission of the European Communities, 1982), but on a
15-point rather than on a five-point scale, by assigning 1,
0 or 2 to each score on the five-point conformation and
fat scales.
Carcass meat, fat and bone proportions were obtained
following dissection of each carcass using the commercial
procedures practiced by the processor. The two sides of
each carcass were quartered into hind- and fore-quarters
between the 12th and 13th rib for bulls and 10th and 11th
rib for heifers. There were seven joints in the hind-quarter
(silverside, topside, striploin, rump, knuckle, fillet and flank
steak) and six in the fore-quarter (chuck, cube roll, brisket,
clod, shoulder blade and flat rib). The weight of meat in
each joint (after bone and dissectable fat had been
removed) was recorded individually. The weight of fat and
bone from each joint was combined for each quarter
separately, to give the total weight for both hind- and forequarters. The total weight of meat was the sum of the
individual meat cuts plus lean trim. Carcass value (value per
kg, c/kg) was the sum of the commercial values of each
boneless, fat-trimmed meat cut and lean trim with a small
deduction for bone expressed as a proportion of cold
carcass weight.
Statistical analysis
Data were analysed using Statistical Analysis Systems
Institute (SAS 2003). Correlations among the variables were
determined using the Proc. CORR procedure and linear
regression analysis was carried out using the Proc. GLM
procedure.
Results
Animal details
Mean, s.d., minimum and maximum and CV values for the
scores, slaughter and carcass traits of the bulls and heifers
are presented in Table 1. Average carcass weights of bulls
and heifers were 323 and 268 kg, respectively. Carcass
conformation and fat scores (scale 1 to 15) for bulls were
11.7 and 6.1, and for heifers were 10.1 and 8.9, respectively. Mean carcass meat, fat and bone proportions for
bulls were 738, 89 and 173 g/kg, respectively. Corresponding figures for heifers were 720, 92 and 188 g/kg.
Correlations using live animal muscular scores
A preliminary examination of the data for the ICBF Assessors showed that correlations of muscular scores using the
average of the entire nine locations with the various carcass
traits were often lower than that obtained using only five
locations (numbers 1 to 5) or just two locations (thigh width
and development of the hind-quarters). Consequently, the
data are presented for nine, five and two locations for both
Assessors A and B. Correlations between muscular scores
taken at weaning and at slaughter by Assessors A (using
five locations), C and D were 0.73, 0.75 and 0.59 for bulls
and 0.44, 0.42 and 0.51 for heifers, respectively. Correlations between Assessors C and D using the same scoring
procedure for bulls and heifers were 0.83 and 0.74 at
weaning, and 0.82 and 0.83 at slaughter, respectively.
Corresponding correlations between muscular scores at
slaughter between Assessors A and B were 0.87 and 0.86.
Assessor A, using the ICBF procedure, found higher
correlations for the muscularity scores at slaughter with
killing-out rate and the various carcass traits than for those
recorded at weaning (Tables 2 and 3). Data from Assessors C
and D, using the Signet scoring procedure, generally showed
good correlations between the muscular scores recorded at
both weaning and pre-slaughter and carcass traits. Although
correlations were generally better pre-slaughter than at
weaning, some exceptionally low correlations were obtained
by Assessor C for the heifers pre-slaughter. Using the data
recorded by Assessor A at weaning, the only correlation
that consistently showed r values of ,0.5 with muscular
score was carcass conformation score. Correlations between
muscular scores and various traits were greatest when using
only two scoring locations (width and development of the
hind-quarter) followed by five scoring locations. The lowest
correlations were obtained when all nine muscular scoring
locations were used. The results obtained using the muscular
score (five locations) recorded by Assessor A pre-slaughter
for both bulls and heifers showed significant positive correlations with killing-out rate (r 5 0.50 and 0.61), carcass meat
proportion (r 5 0.39 and 0.65), carcass value (r 5 0.30 and
0.66) and carcass conformation score (r 5 0.70 and 0.69).
High negative correlations were obtained between muscular
score and carcass bone proportion (r 5 20.51 and 20.68).
Correlations with the proportion of high-value cuts were
positive but variable, whereas those with carcass fat proportions and carcass fat score were generally low and
negative. The results with Assessor A are in general agreement with those obtained with the other Assessors.
Correlations using live animal skeletal scores
Correlations between each of the three individual ICBF
skeletal scores (length of back, length of pelvis and height
at withers) recorded at slaughter by both Assessors A and B
with killing-out rate and the various carcass traits were low
and generally not significant.
Correlations using carcass measurements
Significant (P , 0.001) positive correlations were obtained
in both bulls and heifers for carcass fat depth with carcass
fat proportion (r 5 0.73 and 0.70) and carcass fat score
(r 5 0.64 and 0.72). The only other consistently significant
correlations with carcass fat depth were carcass meat
proportion (r 5 20.71 and 20.59) and carcass value
(r 5 20.64 and 20.51). Correlations with kidney plus
channel fat weight reflected those with carcass fat depth
754
Downloaded from https:/www.cambridge.org/core. IP address: 88.99.165.207, on 16 Jun 2017 at 19:31:54, subject to the Cambridge Core terms of use, available at
https:/www.cambridge.org/core/terms. https://doi.org/10.1017/S1751731108001754
Downloaded from https:/www.cambridge.org/core. IP address: 88.99.165.207, on 16 Jun 2017 at 19:31:54, subject to the Cambridge Core terms of use, available at
https:/www.cambridge.org/core/terms. https://doi.org/10.1017/S1751731108001754
Table 1 Mean, standard deviation, range and coefficient of variation for live animal and carcass traits of bulls and heifers
Bulls
Mean 6 s.d.
a
Scale 1 to 15; bBirth to slaughter.
7.9 6 1.39
8.1 6 1.50
8.5 6 1.52
7.6 6 1.60
7.4 6 1.56
8.5 6 1.25
8.6 6 1.41
9.0 6 1.60
9.2 6 0.95
9.3 6 1.02
9.5 6 1.10
8.5 6 1.80
8.6 6 1.47
540 6 74.8
323.1 6 45.01
599 6 19.4
458 6 20.3
1175 6 130.8
704 6 78.5
11.7 6 1.35
6.1 6 1.51
6.5 6 2.48
3.1 6 1.04
126 6 5.3
738 6 28.5
89 6 24.1
173 6 11.3
82 6 4.1
314 6 13.5
Maximum
5.3
5.2
5.5
4.3
4.7
11.1
11.4
12.0
10.3
10.3
5.2
5.0
4.0
6.3
6.4
6.5
4.7
5.3
406
249.4
560
415
950
570
9.0
3.0
2.2
1.3
114
674
52
153
73.8
287
10.4
10.8
11.5
12.3
12.8
13.0
12.7
11.7
688
429.2
635
494
1490
900
15.0
11.0
11.7
7.0
138
790
15.3
197
90.1
344
Coefficient of variation
17.5
18.6
18.0
6.9
7.1
14.7
16.4
17.8
10.3
10.9
11.6
21.2
17.0
13.9
13.9
3.2
4.4
11.1
11.1
11.6
25.0
38.0
33.1
4.2
3.87
27.2
6.5
5.0
4.3
Mean 6 s.d.
5.8 6 0.85
5.9 6 0.93
6.7 6 1.26
7.1 6 1.66
6.9 6 0.69
8.0 6 1.09
8.1 6 1.11
8.6 6 1.31
8.7 6 0.99
8.6 6 1.14
9.1 6 1.01
7.8 6 1.42
7.9 6 1.35
495 6 45.8
267.9 6 26.4
541 6 18.3
612 6 28.5
809 6 62.3
438 6 37.8
10.1 6 1.22
8.9 6 1.85
6.2 6 1.87
5.5 6 1.78
124 6 4.4
720 6 31.5
92 6 26.4
188 6 11.4
87 6 4.5
317 6 14.2
Minimum
Maximum
Coefficient of variation
3.9
3.6
3.5
4.3
6.0
7.4
7.8
9.5
10.3
8.7
14.8
15.7
18.9
23.4
10.0
6.0
6.4
6.5
6.7
6.2
7.0
5.0
5.3
417.5
217.1
498
540
710
360
8.0
5.0
2.94
0.77
117
665
50
170
78.1
289
10.2
10.6
11.0
10.4
10.6
11.5
11.0
11.7
592.5
319.0
575
657
930
510
12.0
12.0
12.42
9.73
134
772
140
217
96.6
340
13.6
13.8
15.2
17.4
13.3
11.1
18.1
17.2
9.3
9.9
3.4
4.7
7.7
8.6
12.1
20.9
30.3
32.5
3.5
4.38
28.8
6.1
5.16
4.5
755
Value of muscular and skeletal scores as indicators of carcass composition in cattle
Muscular scores at weaninga
ICBF Assessor A: 9 locations
5 locations
2 locations
Signet Assessor C
Signet Assessor D
Muscular scores at slaughtera
ICBF Assessor A: 9 locations
5 locations
2 locations
ICBF Assessor B: 9 locations
5 locations
2 locations
Signet Assessor C
Signet Assessor D
Slaughter weight (kg)
Cold carcass weight (kg)
Killing-out rate (g/kg)
Age at slaughter (days)
Live weight gainb (g/day)
Carcass weight gain (g/day of age)
Carcass conf. score (scale 1 to 15)
Carcass fat score (scale 1 to 15)
Kidney and channel fat (kg)
Carcass fat depth (mm)
Carcass length (cm)
Meat (g/kg)
Fat (g/kg)
Bone (g/kg)
High-value cuts (g/kg)
Carcass value (c/kg)
Minimum
Heifers
Drennan, McGee and Keane
Table 2 Correlations of live animal visual muscular scores taken at weaning with killing-out rate, carcass composition, value and carcass
classification scores
Carcass proportions
Muscular scores
Assessor A: 9 locations Bulls
Heifers
5 locations Bulls
Heifers
2 locationsa Bulls
Heifers
Assessor C
Bulls
Heifers
Assessor D
Bulls
Heifers
Killing-out rate
Meat
Fat
Bone
0.19
0.32*
0.24
0.45**
0.44**
0.52***
0.68***
0.68***
0.53**
0.51**
0.06
0.18
0.10
0.35*
0.30*
0.58***
0.53***
0.68***
0.42**
0.49**
0.10
20.12
0.06
20.25
20.11
20.44**
20.31*
20.53***
20.23
20.35*
20.34*
20.24
20.39**
20.39*
20.54***
20.56***
20.67***
20.63***
20.58***
20.53***
Carcass classification scores
High-value cuts Carcass value
20.09
0.21
20.04
0.35*
0.07
0.50**
0.23
0.59***
0.08
0.44**
0.01
0.24
0.04
0.40*
0.24
0.57***
0.49***
0.72***
0.35*
0.54***
Conformation
Fat
0.47***
0.36*
0.49***
0.46**
0.59***
0.44**
0.73***
0.64***
0.61***
0.55***
0.04
20.13
20.01
20.25
20.12
20.34*
20.15
20.39*
20.21
20.25
a
Width and roundness of hind-quarters.
except that the correlations with carcass fat score were
considerably lower.
Correlations with carcass length were either not significant or low and negative with carcass meat proportion
and carcass value, or low and positive with carcass fat
proportion. Correlations with carcass weight were generally
not significant except for carcass conformation (r 5 0.38
and 0.51).
Correlation of carcass class with carcass composition
and value
High positive correlations (P , 0.001) were obtained (Table 4)
with both bulls and heifers for carcass conformation score
with killing-out rate (r 5 0.68 and 0.57), carcass meat proportion (r 5 0.57 and 0.52) and carcass value (r 5 0.50 and
0.55). Significant negative correlations were obtained for
carcass conformation with both carcass fat and bone proportions, whereas correlations were positive but variable with
the proportion of high-value cuts in the carcass. Correlations
of carcass fat score were high and positive with carcass fat
proportion (r 5 0.83 and 0.74) and negative with carcass
meat proportion (r 5 20.73 and 20.68), carcass value (r 5
20.69 and 20.63), proportion of high-value cuts (r 5 20.54
and 20.31) and killing-out rate (r 5 20.54 and 20.32).
Correlations between carcass fat score and carcass bone
proportion were not significant.
Regression equations relating carcass class to carcass
composition and value
Linear regression equations describing the relationships of
carcass conformation and fat scores with killing-out rate,
carcass meat, fat and bone proportions, the proportion of
high-value cuts in the carcass and carcass value are shown
in Table 5. Increasing conformation score resulted in a
significant increase in killing-out rate, whereas increasing
fat score had a negative effect (not significant for heifers).
The effects of a one-unit change (scale 1 to 15) in carcass
conformation and fat scores on meat proportion (g/kg) for
bulls were 9 and 212 (R2 5 0.70), and for heifers they
were 8 and 210 (R2 5 0.55), respectively. The corresponding figures for carcass value (c/kg) were 3.5 and 25.4
for bulls (R2 5 0.59) and 4.4 and 23.8 for heifers (R2 5
0.51). The proportion of the total variation in carcass fat
proportion explained by carcass conformation and fat
scores was 0.74 and 0.57 for bulls and heifers, respectively.
Corresponding values were 0.34 and 0.30 for carcass bone
proportion, and 0.29 and 0.34 for the proportion of highvalue cuts in the carcass. Improving carcass conformation
score had a negative effect on both carcass fat (not
significant for heifers) and bone (P , 0.001) proportions.
Increasing fat score had a positive effect (P , 0.001) on
carcass fat proportion but had non-significant negative
effects on carcass bone proportion.
Discussion
Experimental animals
On a scale of 1 to 15, the ranges in carcass conformation
scores were from 9 to 15 for the bulls and from 8 to 12 for
the heifers. In addition to the limited range, the animals
were mainly from the upper part of the conformation scale.
The range in fat scores (scale 1 to 15) was from 3 to 11 for
bulls and from 5 to 12 for heifers. Thus, there were no
carcasses in either extreme of fat scores, which for most
markets is unacceptable. This narrow range in class was not
surprising as the animals were 0.75 to 1.0 late-maturing
breed genotypes, which produce carcasses of good conformation score and low fat score (Drennan, 2006).
Assessors
The relatively low correlations, particularly for heifers
(r E 0.45), between muscular scores at weaning and those
recorded by the same Assessor pre-slaughter indicate either
that the Assessors were inconsistent or that the scores
obtained at weaning were not a good indication of those
pre-slaughter. The high correlations (r E 0.80) between
756
Downloaded from https:/www.cambridge.org/core. IP address: 88.99.165.207, on 16 Jun 2017 at 19:31:54, subject to the Cambridge Core terms of use, available at
https:/www.cambridge.org/core/terms. https://doi.org/10.1017/S1751731108001754
Value of muscular and skeletal scores as indicators of carcass composition in cattle
Table 3 Correlations of live animal visual muscular and skeletal scores taken pre-slaughter and carcass measurements with killing-out rate, carcass
composition, value and carcass classification scores
Carcass proportions
Killing-out rate
Muscular scores
Assessor A: 9 locations
5 locations
2 locationsa
Assessor B: 9 locations
5 locations
2 locationsa
Assessor C
Assessor D
Bulls
Heifers
Bulls
Heifers
Bulls
Heifers
Bulls
Heifers
Bulls
Heifers
Bulls
Heifers
Bulls
Heifers
Bulls
Heifers
Skeletal scores
Assessor A: Height at withers Bulls
Heifers
Length of back Bulls
Heifers
Length of pelvis Bulls
Heifers
Assessor B: Height at withers Bulls
Heifers
Length of back Bulls
Heifers
Length of pelvis Bulls
Heifers
Carcass
Fat depth
Bulls
Heifers
Kidney and
Bulls
channel fat
Heifers
Length
Bulls
Heifers
Weight
Bulls
Heifers
0.49***
0.59***
0.50***
0.61***
0.61***
0.63***
0.43**
0.68***
0.50***
0.68***
0.57***
0.60***
0.69***
0.37*
0.69***
0.65***
Meat
0.39**
0.57***
0.39**
0.65***
0.50***
0.69***
0.40**
0.59***
0.47***
0.63***
0.56***
0.52**
0.60***
0.28
0.58***
0.57***
Fat
Bone
20.21
20.38*
20.22
20.48***
20.34*
20.55***
20.23
20.43**
20.29*
20.48**
20.36*
20.34*
20.41**
20.13
20.37*
20.38*
20.53***
20.68***
20.51***
20.68***
20.55***
20.65***
20.53***
20.64***
20.58***
20.64***
20.65***
20.63***
20.62***
20.46**
20.69***
20.68***
20.35
0.05
0.00
0.22
20.11
0.29
20.17
20.18
20.14
20.15
20.27
0.03
20.42**
0.36*
0.03
20.06
20.16
0.13
0.00
0.05
20.10
0.08
0.15
20.16
20.28
0.19
20.40*
0.32
20.30*
0.26
20.30
0.25
20.35*
0.27
20.21
0.19
20.61***
20.21
20.59***
20.71***
20.59***
20.65***
0.73***
0.70***
0.65***
20.25*
20.22
20.05
0.12
0.36*
20.62***
20.33*
20.37*
20.02
0.01
0.69*** 0.11
0.30*
0.20
0.33*
0.26
0.13
20.22
0.08
20.21
Carcass classification scores
High-value cuts Carcass value Conformation
0.11
0.69***
0.11
0.73***
0.18
0.70***
0.12
0.61***
0.20
0.64***
0.32*
0.61***
0.23
0.37*
0.20
0.64***
0.30*
0.60***
0.30*
0.66***
0.48***
0.70***
0.32*
0.61***
0.40**
0.65***
0.53***
0.53***
0.52***
0.31
0.51***
0.58***
0.71***
0.73***
0.70***
0.69***
0.74***
0.73***
0.66***
0.78***
0.68***
0.76***
0.69***
0.74***
0.81***
0.65***
0.71***
0.82***
0.30
0.06
0.13
20.13
0.08
20.04
0.31*
0.38*
0.21
0.26
0.31*
0.14
20.27
20.05
20.16
20.07
20.13
0.15
20.27
20.42**
20.30*
20.35
20.26
20.23
20.41**
20.05
20.21
20.05
20.13
0.20
20.31**
20.37**
20.37**
20.26
20.39**
20.15
20.12
0.27
0.02
0.20
0.11
0.29
20.03
20.17
0.01
20.07
20.02
20.03
0.25
0.02
0.26
20.39**
20.24
20.42**
20.64***
20.51**
20.66***
20.37**
20.28
20.37*
20.30
20.22
20.23
20.20
0.12
20.56***
20.39**
20.34*
20.16
0.05
20.11
20.06
0.04
0.38**
0.51**
Fat
20.20
20.24
20.22
20.32
20.26
20.37*
20.18
20.39*
20.23
20.44***
20.23
20.26
20.34*
20.25
20.27
20.36
0.29*
20.03
0.18
0.03
0.18
0.12
0.21
0.26
0.27
0.07
0.31*
0.15
0.64***
0.72***
0.46**
0.39*
0.25
20.04
0.08
0.01
a
Width and roundness of hind-quarters.
Assessors using the same scoring procedure at the same
time suggest the latter is the case. The discrepancy between
the weaning and pre-slaughter scores may be attributed to
variation in the pre-weaning nutritional level, and thus the
difference in body condition at weaning resulting from
differences in milk production of the dams, which varied in
genotype from beef 3 Holstein/Friesian to purebred Charolais and Limousin. Earlier studies (Drennan et al., 2004)
have shown excellent correlations between live-animal
muscular scores taken pre-slaughter and carcass conformation. However, although lower, corresponding correlations using muscular scores recorded at 8/9 months were
satisfactory in these studies for animals reared on a high
plane of nutrition but less so for those reared on moderate
to low feeding levels. The differences in muscular scores
between Assessors that were relatively small can be
attributed to the use of two different scoring procedures
(ICBF and Signet) and the fact that they involve a subjective
visual assessment of muscular development. To be effective, visual scoring necessitates proper training and
frequent assessment.
Visual muscular scores
The high correlations (r E 0.65 to 0.82) between muscular
scores taken at slaughter and carcass conformation score
indicate that both evaluations provide a fairly similar
description of the animal or carcasses in terms of muscular
development. Higher correlations (r 5 0.81 to 0.87) were
757
Downloaded from https:/www.cambridge.org/core. IP address: 88.99.165.207, on 16 Jun 2017 at 19:31:54, subject to the Cambridge Core terms of use, available at
https:/www.cambridge.org/core/terms. https://doi.org/10.1017/S1751731108001754
Drennan, McGee and Keane
Table 4 Correlations of carcass conformation and fat score with killing-out rate, carcass meat, fat and bone proportion, proportion of high-value
meat cuts in the carcass and carcass value
Carcass proportions
Bulls
Conformation score
Fat score
Heifers
Conformation score
Fat score
Killing-out rate
Meat
Fat
Bone
High-value meat cuts
Carcass value
0.68***
20.54***
0.57***
20.73***
20.41**
0.83***
20.58***
0.07
0.14
20.54***
0.50***
20.69***
0.57***
20.32
0.52***
20.68***
20.39*
0.74***
20.54***
0.17
0.57***
20.31
0.55***
20.63***
Table 5 Regressions on carcass conformation and fat scores (s.e.) of killing-out rate (g/kg) carcass meat, fat and bone proportions (g/kg), the
proportions of high-value meat cuts in the carcass (g/kg), and carcass value (c/kg)
Intercept
Bulls
KO
Meat
Fat
Bone
High-value cuts in carcass
Value
Heifers
KO
Meat
Fat
Bone
High-value cuts in carcass
Value
Conformation score
Fat score
R2
Residual s.d.
531
706
60
234
90
305
8.5
8.9
24.0
24.9
0.04
3.5
(1.36)***
(1.78)***
(1.40)**
(1.04)***
(0.39)
(0.98)***
25.2
211.9
12.4
20.5
21.4
25.4
(1.22)***
(1.60)***
(1.25)***
(0.93)
(0.35)***
(0.88)***
0.62
0.70
0.74
0.34
0.29
0.59
12.3
16.0
12.6
9.4
3.5
8.8
473
723
34
243
70
306
7.9
8.1
22.9
25.2
2.0
4.4
(2.24)**
(3.17)*
(2.63)
(1.44)***
(0.55)**
(1.50)**
21.2
29.7
9.9
20.2
20.3
23.8
(1.48)
(2.09)***
(1.73)***
(0.95)
(0.36)
(0.99)***
0.34
0.55
0.57
0.30
0.34
0.51
15.3
21.7
17.9
9.8
3.8
10.2
KO 5 killing-out rate.
obtained by Drennan et al. (2007) with steers, which may
be partly attributed to the greater range in conformation
scores (2 to 11) in that study. Although the correlations
were high, conformation is defined as the thickness of
muscle and all fat, whereas muscularity is the thickness
of the muscle only (Kempster, 1986). These findings are
in agreement with those of Perry et al. (1993a and 1993b)
who reported correlations of 0.84 and 0.79 between
live-animal and carcass muscle scores, respectively. The fact
that there were negative relationships between muscular
scores pre-slaughter and carcass fat proportion indicates that Assessors did not give animals with more fat a
higher muscular score. The significant positive correlations
obtained between the muscular scores recorded preslaughter and killing-out rate agree with the findings of
Perry and McKiernan (1994). In agreement with Drennan
et al. (2007), high positive correlations were obtained for
pre-slaughter muscular scores with carcass meat proportion
and carcass value, whereas negative correlations were
obtained with carcass bone and fat proportions. The most
important evaluations are the relationships with saleable
meat proportion and carcass value. The latter takes account
of both saleable meat proportion and its distribution in the
carcass. Perry et al. (1993a) and Drennan et al. (2007)
reported correlations of ,0.70 between live-animal
muscular scores taken pre-slaughter and percentage meat
yield, which were higher than those obtained in the present
study (r E 0.60). The lower correlation can probably be
attributed to the smaller range in scores in the present
study. However, May et al. (2000) obtained a considerably
lower correlation of 0.35 between muscular score and
percentage yield of boneless subprimals. Tatum et al. (1986)
found that, within an animal frame size, the percentage
of separable muscle increased, and percentage of bone
decreased, with increased muscle thickness when adjusted to
a constant fat percentage. In contrast, Herring et al. (1994),
using Hereford steers, found no relationship between percentage retail product and a visual muscle score recorded on
the live animal. It is noticeable that in the present study all
muscular score estimates showed high negative correlations
with carcass bone proportions. Therefore, decreased bone
proportion as muscular score increased is an important contributor to the positive association between muscular score
and carcass meat proportion.
In the present study, the results obtained with both ICBF
Assessors showed that correlations of muscular scores at
slaughter with carcass meat proportion and value generally
improved as the number of muscular scoring locations
758
Downloaded from https:/www.cambridge.org/core. IP address: 88.99.165.207, on 16 Jun 2017 at 19:31:54, subject to the Cambridge Core terms of use, available at
https:/www.cambridge.org/core/terms. https://doi.org/10.1017/S1751731108001754
Value of muscular and skeletal scores as indicators of carcass composition in cattle
included in the analysis decreased from 9 to 2. Similarly, in
the study of Drennan et al. (2007), correlations of muscular
score pre-slaughter with carcass meat proportion and value
were equally as good using only two locations (width
and roundness of the hind-quarter) as with six locations.
Consequently, consideration must be given to the selection
of muscular scoring locations and a simplified system
with fewer locations may lead to a better assessment of
important carcass traits. In comparison to muscular scoring
pre-slaughter, scoring at weaning resulted in considerably
lower correlations in most instances with killing-out proportion and the various carcass traits. This was most likely
due to variation in body condition at weaning resulting
from differences in pre-weaning gains as already discussed.
Visual skeletal scores
Correlations of skeletal scores with the various traits were
mainly low and not significant, which is in general agreement with other findings (May et al., 2000; Drennan et al.,
2007). Bailey et al. (1986) reported significant positive correlations for wither height with percentage carcass bone,
non-significant positive correlations with percentage fat and
non-significant (at higher weights) negative correlations
with percentage carcass lean. Similarly, Herring et al. (1994)
reported non-significant negative correlations between percentage retail product and both hip height and a visual frame
size. Afolayan et al. (2007) found that the correlation of body
dimensions with muscularity was near zero.
Carcass measurements
Correlations of carcass fat depth for bulls and heifers were
0.73 and 0.70 with carcass fat proportion and were 0.64
and 0.72 with carcass fat score, respectively. These figures
showed good correlation between carcass fat depth and
the other fat indicators but were somewhat lower than the
correlation between carcass fat proportion and carcass fat
score of 0.83 and 0.74 for bulls and heifers, respectively.
Corresponding significant negative correlations of 20.71
and 20.59 were obtained between carcass fat depth and
carcass meat proportion, which is in general agreement
with previous findings (Griffin et al., 1999; May et al., 2000;
Greiner et al., 2003). Jones et al. (1989) found that an
average fat thickness recorded at the 12th rib explained
0.40 of the total variation in carcass lean content, which
was increased to 0.51 when loin area was also included.
In common with live-animal length scores, carcass length
was poorly correlated with all traits examined, showing
only significant negative correlations (r E 20.36) with
carcass meat proportion and carcass value and significant
positive correlations (r E 0.30) with carcass fat proportion.
There were no significant correlations between carcass
weight and carcass meat, fat or bone proportion although
other studies (Herring et al., 1994; Greiner et al., 2003)
have shown that carcass fat increases and meat declines
with increasing carcass weight. The significant positive
correlations between carcass weight and carcass conformation indicate that conformation score increased as
carcass weight increased. Alternatively, animals of better
conformation tend to have better carcass growth rates and
heavier carcasses.
Carcass class
Correlations of carcass conformation and carcass meat
proportion were lower in the present study (0.57 and 0.52
for bulls and heifers, respectively) than that reported by
Drennan et al. (2007) with steers (r 5 0.80), but similar to
the value of 0.60 obtained by Perry et al. (1993a) for carcass muscle score and saleable meat proportion. The poorer
correlation in the present study compared with Drennan
et al. (2007) maybe due to the greater range in carcass
conformation scores in the previous study. Correlations
of carcass fat score with carcass meat proportion in the
present study (r 5 20.73 and 20.68 for bulls and heifers,
respectively) were similar to those obtained previously (May
et al., 2000; Greiner et al., 2003). Bohuslávek (2002)
obtained correlations of carcass conformation and fat
scores with percentage saleable meat of 0.05 and 20.71,
respectively. However, when examined within fat classes,
significant correlations between conformation and percentage meat yield were obtained with a value of 0.60
recorded with fat class 3 animals.
Regression of carcass composition and value on
carcass scores
In the present study, carcass conformation and fat scores
accounted for 0.70 and 0.55 of the total variation in carcass
meat proportion for bulls and heifers, respectively. The
corresponding figure in the study of Drennan et al. (2007)
for steers was 0.75. Perry et al. (1993a) found that carcass
weight alone, carcass weight with carcass muscle score,
and carcass weight with carcass muscle score and fat depth
accounted for 3.7%, 37.6% and 52.2%, respectively, of the
variation in percentage saleable meat yield. Corresponding
values reported by Perry et al. (1993b) were 0.1%, 37.9%
and 46.7%. Jones et al. (1989) found that a visual fat score,
a muscle thickness score and the combined fat and muscle
scores taken on the cold carcass accounted for 0.42, 0.20
and 0.51, respectively, of the total variation in lean meat
yield. However, Bailey et al. (1986) found that the carcass
conformation score of Holstein 3 Friesian bulls was not a
good indicator of carcass composition as the r values were
20.07, 0.23 and 20.42 with carcass fat, lean and bone,
respectively.
A one-unit increase in carcass conformation score (scale
1 to 15) was associated with a lower increase in carcass
meat proportion (8.9 and 8.1 g/kg for bulls and heifers,
respectively) than that obtained in the study of Drennan
et al. (2007) with steers (14.1 g/kg). However, the corresponding effects of a one-unit (scale 1 to 15) increase in
carcass fat score were greater in the present study (211.9
and 29.7 g/kg for bulls and heifers, respectively) than in
the previous one (27.4 g/kg). The proportion of total variation in carcass value explained by the visually assessed
carcass scores was somewhat less than that for carcass
759
Downloaded from https:/www.cambridge.org/core. IP address: 88.99.165.207, on 16 Jun 2017 at 19:31:54, subject to the Cambridge Core terms of use, available at
https:/www.cambridge.org/core/terms. https://doi.org/10.1017/S1751731108001754
Drennan, McGee and Keane
meat proportion. The proportion of total variation in carcass
fat proportion (R2 E 0.66) explained by carcass scores was
similar to that for meat yield, but values were lower for
carcass bone proportion (R2 E 0.32) and the proportion of
high-value cuts in the carcass (R2 E 0.32). In general, the
various R2 values were lower in the present study than in
the study of Drennan et al. (2007) with steers. This can
probably be attributed to the fact that the bulls and heifers
in the present study were 0.75 to 1.0 late-maturing breeds
and as a result had narrow range of high conformation
scores, whereas in the other study the steers varied from
Holstein-Friesian to .0.9 late-maturing breeds and thus,
had a greater range in conformation scores.
Conclusions
The results show that carcass conformation and fat scores
are effective in predicting carcass meat proportion,
accounting for 0.55 to 0.70 of the total variation. Where
breeding animals are concerned, a live animal muscular
score can be used as an indicator of meat yield but such an
assessment is only useful following the provision of a
relatively high level of nutrition. Assessments carried out on
progeny at weaning may not be useful where pre-weaning
growth rates are low, resulting in poor body condition and
thus, preventing animals from expressing differences in
muscular development. In these circumstances, the scores
would tend to be overly influenced by pre-weaning gain,
which in suckled progeny is mainly a reflection of milk
production of the dam. However, in the present study,
muscular scores taken pre-slaughter were shown to explain
from 25% to 50% of the variation in meat yield.
Acknowledgements
The authors acknowledge the contribution of research student
Ms B. Murphy and the technical assistance of Mr B. Davis.
References
Afolayan RA, Deland MPB, Rutley DL, Bottema CDK, Ewers AL, Ponzoni RW
and Pitchford WS 2002. Prediction of carcass meat, fat and bone yield across
diverse cattle genotype using live-animal measurements. Animal Production in
Australia 24, 13–16.
Afolayan RA, Pitchford WS, Deland MPB and McKiernan WA 2007. Breed
variation and genetic parameters for growth and body development in diverse
beef cattle genotypes. Animal 1, 13–20.
Allen P and Finnerty N 2000. Objective beef carcass classification. A report of a
trial of three VIA classification systems. Teagasc and Department of
Agriculture, Food and Rural Development Publication, 34pp.
Bailey CM, Jensen J and Bech Andersen B 1986. Ultrasonic scanning and body
measurements for predicting composition and muscle distribution in young
Holstein 3 Friesian bulls. Journal of Animal Science 63, 1337–1346.
Bohuslávek Z 2002. Analysis of the commercial grades of beef carcases. Czech
Journal of Animal Science 47, 112–118.
CMMS Statistics Report 2006. Publications by the Department of Agriculture
and Food, June 2007, 60pp.
Collins JME 1998. Genetic evaluation and selection of pedigree beef cattle in
the UK. Signet Base Paper, 26pp.
Commission of the European Communities 1982. Commission of the European
Communities (Beef Carcass Classification) Regulations. Council Regulations
1358/80, 1208/81, 1202/82. Commission Regulations 2930/81, 563/82, 1557/
82, Commission of the European Communities, Brussels.
Drennan MJ, MacAodháin C, Murphy B and Doorley S 2004. Relationship between
visual muscle scores of different animal types taken at 9 months of age and preslaughter with carcass conformation. In Proceedings of the Agricultural Research
Forum. Published by Teagasc, Carlow, Ireland, p. 101 (Abstract).
Drennan MJ 2006. Relationship between beef carcass classification
grades with meat yield and value. In Irish Grassland Association Journal (ed.
D McGilloway), pp. 35–43. Walsh Printer, Roscrea.
Drennan MJ, Keane MG and McGee M 2007. Relationship of live animal
scores/measurements and carcass grades with carcass composition and
carcass value of steers. In Evaluation of carcass and meat quality in cattle and
sheep, EAAP publication No. 123 (ed. C Lazzaroni, S Gigli and D Gabina),
pp. 159–169. Wageningen Academic Publishers, Wageningen.
Greiner SP, Rouse GH, Wilson DE, Cundiff LV and Wheeler TL 2003. Prediction
of retail product weight and percentage using ultrasound and carcass
measurements in beef cattle. Journal of Animal Science 81, 1736–1742.
Griffin DB, Savell JW, Recio HA, Garrett RP and Cross HR 1999. Predicting
carcass composition of beef cattle using ultrasound technology. Journal of
Animal Science 77, 889–892.
Herring WO, Williams SE, Bertrand JK, Benyshek LL and Miller DC 1994.
Comparison of live and carcass equations predicting percentage of cutability,
retail product weight and trimmable fat in beef cattle. Journal of Animal
Science 72, 1107–1118.
ICBF (Irish Cattle Breeding Federation) linear scoring reference guide 2002.
ICBF Society Ltd., Highfield House, Bandon, Co. Cork, Ireland, 17pp.
Jones SDM, Tong AKW and Robertson WM 1989. The prediction of beef
carcass lean content by an electronic probe, a visual scoring system and
carcass measurements. Canadian Journal of Animal Science 69, 641–648.
Kauffman RG, Grummer RH, Smith RE, Long RA and Shook G 1973. Does liveanimal and carcass shape influence gross composition? Journal of Animal
Science 37, 1112–1119.
Kempster AJ 1986. Estimation of the carcass composition of different cattle
breeds and crosses from conformation assessments adjusted for fatness.
Journal of Agricultural Science 106, 239–254.
Kempster AJ and Harrington G 1980. The value of ‘‘fat corrected’’ conformation
as an indicator of beef carcass composition within and between breeds.
Livestock Production Science 7, 361–372.
May SG, Mies WL, Edwards JW, Harris JJ, Morgan JB, Garrett RP, Williams FL,
Wise JW, Cross HR and Savell JW 2000. Using live estimates and ultrasound
measurements to predict beef carcass cutability. Journal of Animal Science 78,
1255–1261.
Perry D and McKiernan WA 1994. Growth and dressing percentage of well and
average muscled Angus steers. Proceedings of Australian Society Animal
Production 20, 349–350.
Perry D, McKiernan WA and Yeates AP 1993a. Muscle score: its usefulness in
describing the potential yield of saleable meat from live steers and their
carcasses. Australian Journal of Experimental Agriculture 33, 275–281.
Perry D, Yeates AP and McKiernan WA 1993b. Meat yield and subjective
muscle scores in medium weight steers. Australian Journal of Experimental
Agriculture 33, 825–831.
Statistical Analysis Systems Institute 2003. SAS/STAT. SAS Systems for
Windows. Release 9.1.3. SAS Institute Inc., Cary, N.C., USA.
Tatum JD, Dolezal HG, Williams Jr FL, Bowling RA and Taylor RE 1986. Effects
of feeder cattle frame size and muscle thickness on subsequent growth and
carcass development. II. Absolute growth and associated changes in carcass
composition. Journal of Animal Science 62, 121–131.
760
Downloaded from https:/www.cambridge.org/core. IP address: 88.99.165.207, on 16 Jun 2017 at 19:31:54, subject to the Cambridge Core terms of use, available at
https:/www.cambridge.org/core/terms. https://doi.org/10.1017/S1751731108001754