Characterization of Canadian grade standards and
lean yield prediction for cows
A. Rodas-González, M. Juárez, W. M. Robertson, I. L. Larsen, and J. L. Aalhus1
Can. J. Anim. Sci. Downloaded from pubs.aic.ca by Alberta Government Library on 03/08/13
For personal use only.
Agriculture and Agri-Food Canada, Lacombe Research Centre, 6000 C & E Trail, Lacombe, Alberta,
Canada T4L 1W1. Received 8 August 2012, accepted 21 November 2012.
Rodas-González, A., Juárez, M., Robertson, W. M., Larsen, I. L. and Aalhus, J. L. 2013. Characterization of Canadian
grade standards and lean yield prediction for cows. Can. J. Anim. Sci. 93: 99107. Commercial carcasses (n 120) were
selected to benchmark the current Canadian grading system for cows (D1, D2, D3, D4; 50% ossification) in comparison
to A/AA grades youthful carcasses [over (OTM) and under (UTM) 30 mo of age based on dentition but B50%
ossification]. With the exception of the D3 and D4 grades, D1 and D2 carcass grades had similar carcass yield attributes
compared with OTM and UTM carcasses; however, rib-eye area from UTM carcasses was the largest (PB0.05), followed
by D1, D2 and OTM. As expected, both OTM and UTM grades had lower ossification scores (PB0.05); however, D4
grade showed the highest marbling score (PB0.05). For carcass composition, compared with all other grades, the D3
grade had the highest proportion of lean (PB0.05) due to a lower proportion of dissectible fat (PB0.05); however, it had
the lightest carcass weight (PB0.05). Using simple measures of carcass characteristics (grade fat, rib-eye area, marbling
and ossification) a prediction equation to estimate lean yield (R2 0.825; Cp 4.31) could be used to more accurately
assess carcass value in cows; however, validation of the equation on a separate population would be required before its
application.
Key words: Canadian grading system, carcass, cows, cutability, lean yield, predictive equation
Rodas-González, A., Juárez, M., Robertson, W. M., Larsen, I. L. et Aalhus, J. L. 2013. Caractérisation des normes de
classement canadiennes et prévision du rendement en viande maigre des vaches. Can. J. Anim. Sci. 93: 99107. Les auteurs ont
sélectionné des carcasses commerciales (n 120) afin d’étalonner le système de classement canadien actuel pour les vaches
(D1, D2, D3, D4;50 % d’ossification) et le comparer aux classes A/AA attribuées aux carcasses des animaux plus jeunes
[plus (OTM) et moins (UTM) de trente mois, selon la dentition B50 % d’ossification]. Hormis les classes D3 et D4, les
carcasses D1 et D2 présentaient les mêmes paramètres de rendement que les carcasses des animaux OTM et UTM. Les
carcasses UTM se caractérisaient néanmoins par la plus grande superficie de faux-filet (PB0,05); venaient ensuite les
carcasses D1, D2 et OTM. Comme il fallait s’y attendre, l’ossification est moins grande (PB0,05) chez les animaux OTM
et UTM; cependant, les carcasses D4 avaient le meilleur persillé (PB0,05). En ce qui concerne la composition des
carcasses, ce sont celles de la classe D3 qui donnent la plus forte proportion de viande maigre (PB0,05), la raison étant
un pourcentage inférieur de gras séparable (PB0,05); ces carcasses étaient néanmoins aussi les plus légères (PB0,05).
En recourant simplement à la quantification des paramètres de la carcasse (épaisseur moyenne du lard dorsal, surface du
faux-filet, persillé et ossification), les auteurs ont formulé une équation qui prévoit le rendement estimatif en viande maigre
(R2 0,825; Cp 4,31) et dont on pourrait se servir pour évaluer avec plus de précision la valeur des carcasses des vaches.
Il conviendrait cependant de valider cette équation avec une population distincte avant de l’utiliser.
Mots clés: Système de classement canadien, carcasse, vaches, rendement boucher, rendement en viande maigre,
équation prévisionnelle
In Canada, mature cows (50% ossification) are
typically sold for consumption as manufacturing beef,
relying heavily on the US market (Canfax 2004).
Disruptions to this market from 2003 to 2007 arising
from a single case of BSE in May 2003 highlighted
the vulnerability of the mature animal market to US
trade (Rude et al. 2007). Canadian mature cow grades
(D grades) have increased significantly in the past years
(from 3.88% of the total graded carcasses in 2003 to
10.09% in 2011), creating a calculated annual surplus in
excess of 160 000 t of meat from mature cows (Canfax
1
Corresponding author (e-mail: Jennifer.Aalhus@agr.
gc.ca).
Can. J. Anim. Sci. (2013) 93: 99107 doi:10.4141/CJAS2012-091
2004, 2011), leading to a drop in price for cow grades.
Hence, the beef industry has been seeking opportunities
to expand domestic markets and improve the carcass
value of mature cows. Current ‘‘cow’’ grades in Canada
are based on a broad classification of carcass types
(Canada Gazette 1992) and little published information
exists regarding the range in composition within or
among grades. Consequently, adding value to cows
may be accomplished by more accurately determining
composition.
Abbreviations: OTM, over 30 mo of age; UTM, under 30 mo of
age; REA, rib-eye area
99
Can. J. Anim. Sci. Downloaded from pubs.aic.ca by Alberta Government Library on 03/08/13
For personal use only.
100 CANADIAN JOURNAL OF ANIMAL SCIENCE
On the other hand, since the re-opening of the border
to meat from cattle under 30 mo of age (UTM), a new
category of youthful animals has been established by
the industry. So called ‘‘blue-’’ or ‘‘red-’’ back carcasses
(due to the rolling of blue or red ink down the backbone
to identify them), they are graded as youthful carcasses,
based on ossification (B50%), but, based on dentition,
are deemed to exceed 30 mo of age (OTM). Unfortunately, physiological age, based either on dentition or
ossification, is not accurately related to chronological
age (Lawrence et al. 2001; Chaudhary et al. 2008) yet in
the absence of recorded birthdates dentition has been
used for international trade. While OTM carcasses may
be falling into the more mature end of the youthful
grade, it is unlikely there is any quality-based reason
to discount the carcasses. Consequently, the objectives
of this study were: (a) to benchmark the Canadian
grading standards for cows compared with youthful
carcasses (over/under 30 mo of age) for carcass traits
and cutability; (b) to determine the potential to develop
a predictive equation for lean content in cow carcasses.
MATERIALS AND METHODS
Handling and slaughtering of animals at a commercial
abattoir followed the humane practices described by the
Canadian Council on Animal Care (1993).
Carcass Selection
Carcasses representative of the four Canadian mature
cow grades (D1, D2, D3, D4, n 21 of each grade)
were selected at the time of grading from a commercial
abattoir by a certified beef grader [Canada Gazette
1992; Canadian Beef Grading Agency (CBGA) 1998].
At the same time, physiologically youthful carcasses
(B50% ossification) in yield grade Y1 (59% or more of
lean) and quality grade A or AA (Canada Gazette 1992)
were selected based on a dentition breakpoint of under
30 mo (UTM; n 18; no permanent incisors) and over
30 mo (OTM; n 18; two or more permanent incisors)
of age. The expression UTM and OTM are acronyms
used by the beef industry for physiologically youthful
carcasses (B50% ossification).
Following selection, additional grade data were recorded according to the Livestock and Poultry Carcass
Grading Regulations (Canada Gazette 1992), including
muscling score (determined on the basis of rib-eye length
and width measurements), body-type (beef or dairy),
ossification (percentage of ossification of spinal process
at 11th and 12th thoracic vertebrae), grade fat (minimum backfat thickness in the 3rd quarter between the
12th and 13th rib interface), rib-eye area (REA; between
the 12th and 13th rib interface), fat colour (yellow
fat presence). Marbling scores were assessed using
United States Department of Agriculture marbling
standards (USDA 1989). Left sides were shipped to
the Agriculture and Agri-Food Canada Meat Research
Centre (Lacombe, AB) by way of refrigerated truck.
Following delivery, carcasses were weighed and held in
a carcass cooler at 28C with wind speeds of 0.5 m s 1
until 67 d post-mortem.
Carcass Fabrication
Left carcass sides were weighed (cold carcass weight) to
determine cooler shrink loss and fabricated according to
the Canadian Meat Council (1988) into nine wholesale
cuts or primals (158 round, 181A sirloin butt, 173 shortloin, 193 flank, 113 chuck, 103 rib, 121 plate, 120
brisket, 117 fore shank). Later on, all bone-in cuts were
further deboned and dissected in order to obtain the
total body-cavity fat, subcutaneous fat and intermuscular fat, lean and bone. Body-cavity fat is considered fat
located on inner side of the brisket, plate, ribs, loin,
chuck, and inner and outer side of diaphragm; as well as
kidney, pelvic and heart fat where it remains with the
carcass. Subcutaneous fat (fat removed from outside or
exposed side of the primal cut) was completely removed,
leaving the cut without a fat layer. After removing bodycavity and subcutaneous fat, intermuscular fat was
obtained by removing all fat found in seams between
muscles. Trimmings higher than 90% lean were considered as lean tissue, whereas trimmings less than
90% lean were considered as fat tissue and sorted in
their corresponding fat depot for each primal. Weights
for all previously mentioned products of fabrication
were transformed to relative content and expressed as
grams per kilogram carcass side weight and grams per
kilogram primal weight.
Statistical Analysis
Carcass data and cutout characteristics were analyzed
using the MIXED model procedures of SAS software
version 9.2 (SAS Institute, Inc. 2003). Analysis of
variance was performed for completely randomized
design model, having carcass grades (D1, D2, D3, D4,
OTM, and UTM) as the main effect. The individual
carcass was included as a random factor. Least squares
means were separated (F test, PB0.05) using least
significant differences generated by the PDIFF option.
The degrees of freedom in the denominator were
adjusted using the KenwardRoger procedure.
Simple descriptive statistics (PROC MEANS) were
computed for carcass traits and composition. Correlation analysis was performed to determine the relationship of carcass traits (yield factors) to the dissected
lean yield proportion. The Snedecor criteria was used
to qualify the values of r as high, moderate or low
(high: ]0.7; moderate: between 0.5 and 0.7; low: 50.5).
Variance inflation factors (VIF) and collinearity diagnostics (COLLINOINT) from the PROC REG procedure of SAS software (SAS Institute, Inc. 2003) were
used to detect multicollinearity prior to stepwise regression analyses. In order to evaluate the precision and
accuracy of the equation obtained for cows, the
dissected vs. new predicted lean yield percentages were
plotted, and a linear regression was computed. Also, this
plot was contrasted against the dissected vs. predicted
RODAS-GONZÁLEZ ET AL. * CANADIAN GRADE STANDARDS FOR COWS
lean yield percentage determined using the existing lean
algorithm previously developed for Canadian youthful
carcasses (Canada Gazette 1992).
Can. J. Anim. Sci. Downloaded from pubs.aic.ca by Alberta Government Library on 03/08/13
For personal use only.
RESULTS AND DISCUSSION
Carcass Traits
Mature carcasses based on evaluation of the degree
of ossification of the spinal processes and ribs, fall into
the D grades (Canada Gazette 1992; CBGA 1998).
Carcasses from bulls or stags of any age which show
pronounced masculinity fall into the E grade. To qualify
for the D1 grade, mature carcasses must have excellent
muscling and be well finished with white to amber fat
(B15 mm backfat). Mature carcasses with medium to
excellent muscling or with yellow fat fall into the D2
grade. Mature carcasses which are deficient in muscling
to the point of emaciation receive a D3 grade, whereas,
over-fat mature carcasses with deficient to excellent
muscling (15 mm backfat) receive a D4 grade.
In the population studied, D1 and D4 carcasses
were heavier (P B0.05) than the other D and both the
UTM and OTM youthful grades (Table 1). The D2 and
youthful grades had similar cold carcass weight; D3
grades had the lightest carcass weights. Furthermore,
D4 grade carcasses had greater backfat depth (P B0.05)
than the other D and youthful grades; D3 had the least
backfat. The REA from UTM carcasses was the largest
(P B0.05), followed by D1, OTM and D2. Carcass D3
and D4 grades had the smallest REA. As expected,
OTM and UTM carcasses had the lowest (P B0.05)
percentage of ossification of the spinal process at the
11th and 12th thoracic vertebrae compared with D
carcass grades and no presence of yellow fat colour.
Nevertheless, the D4 grade obtained the highest marbling scores (P B0.05; ‘‘Modest’’), followed by D1, D2,
and OTM (‘‘Modest’’ to ‘‘Small’’), next by UTM
101
(‘‘Small’’) and finally D3 with the lowest marbling
score (‘‘Traces’’). According to the 2001 Canadian
Beef Quality Audit (Van Donkersgoed et al. 2001), top
quality Canadian grade heifers and steers presented
numerically heavier carcasses and larger REA than
cows, but similar grade fat thickness. Also, the range
in carcass traits and lean percentage in the present study
were higher than those reported in the Canadian Beef
Quality Audit for cows (Van Donkersgoed et al. 2001),
which makes the present population ideal for developing lean yield prediction equations. In the 2001 audit,
the average hot carcasses weight was 300 kg, REA was
75 cm2 and grade fat of 8 mm, with an average lean
percentage of 56.6%.
In contrast, in a study (Stelzleni et al. 2007) comparing feeding cull cows vs. youthful USDA Select steer
carcasses, cull cows fed with a high energy ration before
slaughter had smaller rib-eye area and medium muscle
conformation than A-maturity USDA Select carcasses.
However, the cull cows (especially beef-type) also
had more marbling and backfat thickness. A-maturity
USDA Select carcasses had more desirable carcass
characteristics (brighter lean colour and whiter backfat)
than cull cows that did not receive a high energy ration
prior to slaughter. In the present study, the information
about management history of the cows was unavailable.
Regardless of feeding history, D1 and D2 carcasses
had similar carcass characteristics to OTM and UTM
carcasses, with the exception of higher marbling and
ossification. Intramuscular fat is closely linked to fatty
tissue development and is deposited over a long period
of growth (Berg and Butterfield 1968; Robelin 1986);
thus, cows are likely to have high levels of marbling as
animals mature. Greater ossification has been shown
to decrease tenderness (Smith et al. 1982, 1988; Hilton
et al. 1998) and increased marbling has been shown to
Table 1. Carcass traits from mature cattle quality grades and youthful gradesz groups
Canadian grade
D1
D2
D3
D4
OTM
UTM
Trait
n 21
n 21
n21
n 21
n18
n 18
SEM
P value
Cold carcass weight (kg)
Grade fat (mm)y
Rib-eye area (cm2)
Ossification (%)x
Marbling scorew
Yellow fat presence (%)v
359a
8.71b
90.1b
88.5b
517ab
0.00
331b
7.38bc
84.5bc
94.2ab
491bc
9.17
310c
0.43d
81.1c
96.4a
272e
6.67
359a
21.76a
78.5c
91.9ab
543a
4.17
334b
7.67b
89.7b
6.39c
448cd
0.00
325bc
6.06c
97.5a
0.00c
424d
0.00
5.85
0.54
2.46
2.61
18.9
B0.001
B0.001
B0.001
B0.001
B0.001
B0.001
z
Canada beef grading system (Canada Gazette 1992).
D1 to D4: Canadian quality grades for mature animals.
OTMA/AA youthful physiologically and over 30 mo based on dentition.
UTMA/AA youthful physiologically under 30 mo based on dentition.
y
Backfat thickness between the 12th and 13th ribs’ interface.
x
Percentage of ossification of spinal process at 11th and 12th thoracic vertebrae.
w
USDA marbling standards: 200299traces; 300399slight; 400499small; 500599 modest; 600699moderate; 700799 slightly
abundant; 800899moderately abundant; 900999 abundant; 10001099very abundant.
v
Chi-square analysis indicated the distribution was different by carcass grades.
ae Least squares means within a row lacking a common letter differ (PB0.05).
Can. J. Anim. Sci. Downloaded from pubs.aic.ca by Alberta Government Library on 03/08/13
For personal use only.
102 CANADIAN JOURNAL OF ANIMAL SCIENCE
improve palatability and consumer acceptance (Savell
et al. 1987; Neely et al. 1998; Killinger et al. 2004).
Opportunity to capitalize on the higher marbling content in these grades would likely require concomitant
intervention strategies for tenderness.
Based on ossification both UTM and OTM carcasses
would fall into the same grade. However, to facilitate
international trade, UTM and OTM carcasses are separated based on dentition. The present study indicates
UTM and OTM carcasses were similar. The only differences between OTM and UTM were for grade fat and
REA, where OTM grades presented thicker backfat and
smaller REA compared with UTM carcasses (P B0.05).
Although not significantly different (P 0.05), OTM
carcasses had a numerically higher ossification percentage (6.39%) compared with UTM carcasses (0.00%).
Carcass Cutout
The D3 carcass grades had the highest proportion of
lean (P B0.05) due to lower proportions of dissectible
fat components (P B0.05; body cavity, subcutaneous,
intermuscular and total), and despite a higher proportion of bone (P B0.05; Table 2). In contrast, D4 carcass
grades had the lowest proportion of lean and bone; but
much higher proportions of subcutaneous, intermuscular and total fat. The D1, D2, OTM and UTM had
intermediate values for most of the dissectible components and were generally very similar in composition.
No differences in dissectible tissue components were
detected between OTM and UTM (P 0.05). Despite
these differences in proportional yields when carcass
weights were taken into account, the highest actual lean
yield in absolute terms (kg) was found in the D1 (219.7
kg; data not shown) and the lowest in the D4 carcasses
(198.5 kg), representing an average of 21.2 kg more lean
meat in the D1 carcass grade. In monetary terms, this
would equate to an additional revenue of CDN $99.85
(CDN $4.71 kg 1 cow trim 85%; Canfax 2012).
Primal cut yields (Table 2) indicated D1, D2 and D4
carcass grades had higher proportions of sirloin butt
and flank than the other carcass grades (P B0.05). In
addition, OTM and UTM carcasses had higher proportions of brisket. The D4 carcass grades were mainly
differentiated by higher proportions of short loin, rib
and plate (P B0.05). The proportions of round and
chuck were higher in D3 carcass grades; even though,
UTM carcasses also had higher proportions of round.
The proportion of fore shank was higher in D3, UTM
and OTM carcass grades.
Except for the proportion of lean in the fore shank
where there were no statistical differences among grades
(P 0.05; Table 3), the proportion of lean in most of
the primals was higher in D3 carcass grades than the
other grades (P B0.05), followed by D1, D2, OTM and
UTM, and then D4. The UTM had a higher proportion
of lean in the sirloin butt and short loin primals compared with other grades (P B0.05), but always ranked
second after the D3 carcass grade. The proportion of
Table 2. Carcass components and full dissection valuesz from mature cattle quality grades and youthful grades groups
Canadian grade
Carcass composition (g kg
Total lean
Total bone
Total body cavity
Total subcutaneous fat
Total intermuscular fat
Total fat
D2
D3
D4
OTM
UTM
n21
n 21
n 21
n18
n 18
SEM
P value
612b
171c
24.5b
65.0b
128b
217b
611b
182b
24.3b
60.1bc
123b
207b
693a
215a
12.4c
15.2d
64.6c
92.3c
553c
157d
29.5a
102a
159a
290a
606b
175bc
23.9b
64.2bc
131b
219b
623b
171c
23.8b
55.2c
127b
206b
7.04
3.13
1.13
3.03
4.43
7.53
B0.001
B0.001
B0.001
B0.001
B0.001
B0.001
241c
99.9a
71.5b
51.8bc
93.8b
278b
73.6b
54.0a
35.2b
241c
99.9a
64.6cd
55.0ab
93.5b
281b
71.3bc
56.2a
36.3b
262a
95.4b
63.5d
40.9d
89.4c
292a
68.3c
48.7b
38.5a
219d
100a
77.5a
58.6a
102a
275b
78.8a
55.2a
32.3c
252b
94.6b
68.8bc
49.4c
90.8bc
281b
70.1bc
53.9a
37.4ab
260a
85.4c
69.8b
48.6c
92.9bc
278b
68.0c
56.5a
39.2a
2.48
1.47
1.56
1.55
1.31
2.73
1.84
1.64
0.79
B0.001
B0.001
B0.001
B0.001
B0.001
0.001
0.001
0.011
B0.001
1
Primal cut yields (g kg1)
Roundy
Sirloin buttx
Short loinx
Flankx
Riby
Chuckw
Platew
Brisketw
Foreshankw
z
D1
n 21
)
Yield calculated on base on carcasses side weight.
OTMA/AA youthful physiologically and over 30 mo based on dentition.
UTMA/AA youthful physiologically under 30 mo based on dentition.
y
Hind carcass section.
x
Middle carcass section.
w
Front carcass section.
ad Least squares means within a row lacking a common letter differ (P B0.05).
RODAS-GONZÁLEZ ET AL. * CANADIAN GRADE STANDARDS FOR COWS
103
Table 3. Dissection valuesz of individual primals (g kg1) from mature cattle quality grades and youthful grades groups
Canadian grade
Trait
Can. J. Anim. Sci. Downloaded from pubs.aic.ca by Alberta Government Library on 03/08/13
For personal use only.
y
D1
D2
D3
D4
OTM
UTM
n 21
n 21
n 21
n 21
n 18
n 18
SEM
P value
Round
Lean
Bone
BC fat
SQ fat
IM fat
703b
170bc
5.43b
60.6b
60.8a
687bc
178b
6.05ab
62.5b
66.4a
731a
200a
2.90c
24.2c
41.7b
676c
164c
6.77a
87.1a
65.7a
687bc
176b
5.75ab
64.9b
65.7a
695b
176b
5.70ab
60.5b
62.9a
5.93
3.09
0.44
3.55
2.52
B0.001
B0.001
B0.001
B0.001
B0.001
Sirloin
Buttx
Lean
Bone
BC fat
SQ fat
IM fat
607cd
161c
57.0ab
94.8b
80.5a
594d
175b
62.1ab
94.7b
74.3a
702a
207a
29.5c
16.3d
46.4b
527e
150c
64.6a
175a
83.1a
620c
162c
56.4ab
82.0b
80.2a
650b
156c
54.2b
63.9c
75.9a
8.34
4.24
3.60
5.91
3.79
B0.001
B0.001
B0.001
B0.001
B0.001
Short
Loinx
Lean
Bone
BC fat
SQ fat
IM fat
565c
177c
91.9b
127b
39.1a
569c
201b
81.8b
109cd
39.6a
663a
252a
47.4c
25.0e
13.2b
468d
152d
108a
226a
45.6a
576c
176c
82.6b
117bc
48.4a
606b
175c
82.7b
92.8d
44.4a
9.22
5.67
5.40
6.38
3.53
B0.001
B0.001
B0.001
B0.001
B0.001
Flankx
Lean
Bone
IM fat
522b
16.5bc
462b
525b
18.7b
458b
724a
29.8a
246c
400c
11.8c
588a
504b
14.0bc
482b
529b
12.7c
459b
12.28
1.77
12.84
B0.001
B0.001
B0.001
Ribx
Lean
Bone
BC fat
SQ fat
IM fat
545b
210c
17.6b
95.0b
133b
549b
228b
18.3ab
85.1b
119b
655a
276a
9.63c
11.8c
48.0c
466c
186d
20.4ab
155a
174a
549b
210c
20.9a
95.1b
125b
567b
204c
20.8a
83.4b
125b
8.64
4.49
1.12
5.18
6.06
B0.001
B0.001
B0.001
B0.001
B0.001
Chuckw
Lean
Bone
BC fat
SQ fat
IM fat
652b
164bc
10.1a
40.3b
133bc
661b
172b
10.4a
35.4b
121c
723a
194a
5.69b
7.68c
70.5d
615c
156d
10.0a
57.9a
162a
645b
167bc
10.1a
42.0b
136bc
658b
159.6cd
10.1a
35.3b
137b
7.00
3.14
0.94
2.45
5.35
B0.001
B0.001
0.003
B0.001
B0.001
Platew
Lean
Bone
BC fat
SQ fat
IM fat
516b
156b
74.6a
73.9b
180bc
534b
165b
77.5a
71.6b
152c
656a
220a
39.6b
16.8d
67.0d
454c
122c
89.7a
103a
231a
507b
160b
78.8a
72.5b
182bc
518b
162b
89.7a
42.8c
187b
10.73
6.06
5.69
5.77
10.59
B0.001
B0.001
B0.001
B0.001
B0.001
Brisketw
Lean
Bone
BC fat
SQ fat
IM fat
Lean
Bone
IM fat
484b
180c
17.9a
113ab
205b
487
394bc
119b
487b
208b
16.3a
92.9b
196b
484
398b
118b
583a
265a
11.1b
26.6c
115c
491
431a
77.5c
441c
172c
20.0a
135a
232a
478
377c
145a
467bc
186c
19.0a
116ab
212ab
460
404b
137a
487b
169c
15.6ab
124a
205b
488
396bc
116b
11.09
7.32
1.91
9.84
8.13
7.67
7.25
6.00
B0.001
B0.001
0.018
B0.001
B0.001
0.067
B0.001
B0.001
Fore
Shankw
z
Yield calculated on base on primal weight.
BC, body cavity; SQ, subcutaneous; IM, intermuscular.
OTMA/AA youthful physiologically and over 30 mo based on dentition.
UTMA/AA youthful physiologically under 30 mo based on dentition.
y
Hind carcass section.
x
Middle carcass section.
w
Front carcass section.
ad Least squares means within a row lacking a common superscript letter differ (PB0.05).
bone was higher in the D3 carcass grade in all
primals (P B0.05), and D2 carcasses ranked second
with higher proportion of bone in the sirloin butt,
short loin, rib and brisket (P B0.05). In contrast, D4
carcasses had the lowest proportion of bone (P B0.05).
For the fat depot proportions, D3 carcasses had the
lowest proportion of dissectible fat depots (P B0.05;
body cavity, subcutaneous, and intermuscular fat)
with respect to the other grades. On the other hand,
even though D4 carcass grades had higher proportions
of total fat (P B0.05), for some fat depots, dependent
on primal, the proportions were similar to D1, D2,
OTM and UTM; for example, body cavity in the sirloin
butt, chuck, rib, plate and brisket, as well as intermuscular fat in round, sirloin butt, and short loin
(P 0.05).
Can. J. Anim. Sci. Downloaded from pubs.aic.ca by Alberta Government Library on 03/08/13
For personal use only.
104 CANADIAN JOURNAL OF ANIMAL SCIENCE
To understand the value of mature cows in the market
place according to the types of carcases found in these
grade classes, the lean meat yield in absolute terms (kg)
can be estimated. For example, in the D1 grade with a
carcass weight of 350 kg, the round would yield approximately 59 kg of lean [e.g. 350 kg 0.241 (Table 2) 0.703 (Table 3) 59 kg lean]; conversely, a D4 cow
that weighed the same would yield 52 kg of lean (e.g. 350
kg 0.219 0.676 52 kg lean). Consequently, packers
can use this information make improved decisions
regarding the kind of cow carcass grades needed for
merchandisable cuts or for manufacturing beef products
(i.e., ground beef). At the same time, producers can
increase their revenue through cow management and
marketing improvements to supply the mature cows that
meet market needs.
Stelzleni et al. (2007) reported beef cull cows fed a
low-energy diet had similar proportions of lean and fat
to USDA Select A-maturity steer, but had higher lean
and lower fat proportions than cull cows (either beef
or dairy cows) fed a high-energy diet. Most Canadian
studies have been conducted on youthful rather than
mature female animals and have denoted certain carcass
composition disadvantage when compared with males.
Fredeen et al. (1981) reported higher carcass lean
content for A1 grades from steers than heifers, but
these sex differences gradually diminished as yield class
increased (A1 to A4). Jones et al. (1987) also indicated
that for A1 carcasses, steers had a higher lean proportion than heifers; however, A2 carcasses from both sexes
had similar lean content with or without adjustment
to the same level of backfat thickness. In both studies,
the differences in lean proportion were due to a higher
proportion of trimmed fat on heifer carcasses.
Cull Cow Predictive Equation for Lean
For cull cow carcass traits (Table 4), a wide range of
variation was observed in the rib-eye width (CV 43.57%) and overall muscle score (CV 39.78%), while
grade fat, fat class, REA, rib-eye length, marbling and
ossification presented moderate to low ranges of variation (CV 22 to 12%). Cold carcass weight showed
lower variation (CV 7.27%). Overall, although the
variation in total dissected lean content ranged from
52 to 77%, the CV was relatively low (4.32%; data not
shown). A small variation in body measurements
(lengths and areas) and a wide variation in the indicators
of body fat have been reported by other authors
(Abraham et al. 1980; Atencio-Valladares et al. 2008)
for cattle. The findings of the current study agree with
those of Johnson and Rogers (1997); when working with
mature cows, they found a moderate to low range of
variation in most of carcasses traits, with the exception
of marbling (CV of 56%). Similarly, O’Mara et al.
(1998) reported higher variability for marbling score
(44.76%).
The correlation coefficients for carcass traits and lean
yield percentage are presented in Table 4. According to
Snedecor criteria, grade fat, fat class and marbling score
variables could be good estimators of lean yield percentage (LEAN) (r ]0.700 and P B0.001). These variables had negative associations, indicating that increases
in fat deposition would result in lower LEAN. On the
other hand, cold carcass weight had moderate negative association (r0.452 and P B0.001), while REA
(cm2) and rib-eye length presented low positive association with LEAN (r0.226 and 0.239, respectively and
P B0.05). A positive trend (r 0.200 and P 0.067) was
observed for ossification scores. Rib eye width (mm) and
Table 4. Independent variable range and their correlation with dissected lean yield in the population of cull cows
Lean yield percentage correlation
z
Carcass traits
N
Mean
STD
Cold carcass weight (kg)
Grade fat (mm)y
Fat classx
Rib eye area (cm2)
Rib eye width (mm)
Rib eye length (mm)
Muscle scorew
Marblingv
Ossificationu
84
84
76
84
76
76
76
84
84
346
9.59
4.58
83.6
45.1
67.5
2.45
456
92.7
25.2
2.05
0.83
10.2
20.0
13.0
0.97
95.5
13.2
z
CV
z
7.27
21.4
18.1
12.2
43.6
19.2
39.8
21.0
14.2
Min
Max
rt
P value
307
6.25
3.00
66.3
25.4
38.1
1.00
310
54.0
391
14.0
6.00
106
76.2
76.2
4.00
671
100
0.452
0.842
0.822
0.226
0.047
0.239
0.129
0.725
0.200
B0.001
B0.001
B0.001
0.038
0.686
0.038
0.267
B0.001
0.067
STD, standard deviation; CV, coefficient variation.
Backfat thickness between the 12th and 13th ribs’ interface.
x
Determined on the basis of back fat thickness: 3 6 or 7 mm; 614 or 15 mm.
w
Determined on the basis of rib-eye length and width measurements: 1B141 mm length and B64 mm width; 4150 length and 71 mm
width.
v
USDA marbling standards: 200299traces; 300399slight; 400499small; 500599modest; 600699 moderate; 700799slightly
abundant; 800899moderately abundant; 900999 abundant and 10001099very abundant.
u
Percentage of ossification of spinal process at 11th and 12th thoracic vertebrae.
t
r, Pearson correlation coefficient.
y
Can. J. Anim. Sci. Downloaded from pubs.aic.ca by Alberta Government Library on 03/08/13
For personal use only.
RODAS-GONZÁLEZ ET AL. * CANADIAN GRADE STANDARDS FOR COWS
105
and ossification slightly improved the model (R2 0.81
and 0.83, respectively). However, when ossification was
included as a fourth variable, it reduced the Mallow’s
coefficient (Cp 4.31 vs. 7.44), thus improving the
model accuracy. Consequently, based on the current
dataset the best equation to predict LEAN in cull cows
was: LEAN 59.2131 (grade fat 0.3869)(REA 0.0946) (marbling 0.0152)(ossification 0.0515).
The Canadian youthful lean yield algorithm was not
designed to accommodate mature carcasses, only youthful carcasses in Canada Prime and A quality grades.
However, in this study a new equation for mature cow
carcasses was developed and was compared with the
results obtained using the yield algorithm developed for
youthful carcasses [(lean% 63.651.05 (muscle score)
0.76 (grade fat)]. Both equations (the new predictive
LEAN equation for cows and the currently used predictive LEAN equation for youthful animals) were
contrasted (Fig. 1). As expected, the results indicate
that the new lean yield equation for cows was more
precise in predicting the actual lean yield percentage
(R2 0.83) than the equation used for youthful animals
(R2 0.70).
In agreement with other studies (Kauffman et al.
1975; Abraham et al. 1980; Savell et al. 1987; Smith
et al. 1988; Johnson and Rogers 1997; Neely et al. 1998;
O’Mara et al. 1998; Killinger et al. 2004; AtencioValladares et al. 2008), grade fat, REA and marbling
score were included in multiple regression equations for
predicting cutability and were useful predictors in the
current study. Johnson and Rogers (1997) reported the
best equation for predicting the yield of whole muscle
cuts from mature cow carcasses had three variables
(hot carcass weight, rib-eye area and marbling) but, the
percentage of total variation explained in their study
was relatively low (R2 0.58). Interestingly, their equation contained hot carcass weight, which invariably is
collinear with the proportion of lean per unit of carcass
weight. O’Mara et al. (1998) used USDA yield and
quality grade factors in cows to predict LEAN content.
The best carcass traits for their LEAN prediction model
included adjusted preliminary yield grade, rib-eye area
adjustment, marbling score and lean maturity, resulting in a high R2 (0.79). Given the differences in cattle
populations, comparison with other foreign prediction
muscle score were not significantly correlated with
LEAN (P 0.05).
Some researchers (Kauffman et al. 1975; Abraham
et al. 1980; Johnson and Rogers 1997; O’Mara et al.
1998) have reported that carcass traits for evaluating
fatness (backfat thickness and marbling) from mature or
young animals had the highest simple correlation to
LEAN. On the other hand, Johnson and Rogers (1997)
also indicated that bone maturity from cows was not
associated with LEAN, while REA and carcass weight
had a low association. These findings agree with the
results of current study. Other researchers (Crouse et al.
1975; Abraham et al. 1980; Atencio-Valladares et al.
2008) have indicated that carcass weight has little
predictive power for LEAN. Although, ossification
was not associated with total LEAN proportion, during
the correlation analysis, positive correlation between
ossification and lean proportion in some primal cuts
(chuck, rib and plate, results not shown) was detected.
In consequence, when a tendency (P 0.07) was detected in the relationship between ossification and total
LEAN proportion, it was considered a rational decision
to include it in the stepwise regression analysis. Additionally, during post-natal development, bone has slow
growth and maturity rate than muscle and fat (Berg
and Butterfield 1968; Van Sickle 1985). However, the
implications of relative tissue growth for evaluation of
carcass composition are that bone percentage decreased
continuously in relation to the other tissue; thus, the
stage of development at slaughter can influence carcass
composition (Berg and Butterfield 1968). Thus, it can be
assumed that more ossification (50100%) could lead to
a higher muscle:bone ratio.
Due to a lack of association (rib-eye width and muscle
score) some variables were discarded and the rest of the
traits were considered as predictors of LEAN (they did
not present multicollinearity). The better predictive
equation was selected based on the highest determination coefficient (R2) and the lowest Mallow’s coefficient
(Cp) (Table 5). Stepwise regression included grade fat,
rib-eye area, marbling and ossification as predictors
of LEAN. Grade fat alone contributed the most to
prediction of LEAN (R2 0.70; P B0.001). Further,
stepwise inclusion of marbling score improved the
model (R2 0.78), whereas inclusion of REA (cm2)
Table 5. Regression equations for predicting carcass lean yield percentages
Coefficient
Equation
Intercept
GFAT
MARB
REAz
OSSIz
R2y
Cpy
P value
1
2
3
4
66.9619
71.7917
64.6708
59.2131
0.5815
0.4416
0.4074
0.3869
0.0136
0.0891
0.0946
0.0151
0.0152
0.0515
0.70
0.78
0.81
0.83
48.83
17.10
7.45
4.31
B0.001
B0.001
0.001
0.026
z
z
z
GFAT, grade fat; REA, rib eye area; MARB, marbling score; OSSI, ossification.
R2, coefficient of determination; Cp, Mallow’s coefficient.
y
Can. J. Anim. Sci. Downloaded from pubs.aic.ca by Alberta Government Library on 03/08/13
For personal use only.
106 CANADIAN JOURNAL OF ANIMAL SCIENCE
Within the mature carcass grades, D1 and D4 cow
carcasses had the most marbling, slightly lower REA,
and less yellow fat presence; thus, meat from these
carcasses may be used in value added products with
inclusion of tenderness interventions. The D3 carcasses
have values for production of manufacturing beef due to
their overall low fatness resulting in high proportional
lean meat yield.
The present data show the Canadian grade classes for
mature cattle do not do an adequate job of segregating
carcasses on lean yield based on consideration of limited
carcass characteristics. Consequently, the equation to
predict LEAN developed in the present study explained
over 83% of the variation, indicating that there may be
an opportunity to develop a yield grade for cows and
more precisely define their carcass value.
ACKNOWLEDGEMENTS
This study was funded by Agriculture and Agri-Food
Canada as part of their BSE Recovery Strategy. The
authors sincerely acknowledge the cooperation of XL
Beef and assistance for in-plant grading provided by
Mr. Fred Taylor. We thank the Meat Processing staff
and Mr. Stan Landry from the Lacombe Research
Centre for their technical assistance.
Fig. 1. Contrasting the new predictive lean yield equation for
cull cows vs. the predictive equation from Canada lean yield
grade. The new predictive equation for cull cows is: LEAN 59.2131 (grade fat0.3869)(REA0.0946) (marbling 0.0152)(ossification 0.0515). The predictive equation for
youthful animals: LEAN 63.651.05 (muscle score) 0.76
(grade fat).
equations could lead to inaccurate predictions (Lee
et al. 2005). Furthermore, for illustration purposes only,
the new equation was tested on the same population
used to develop the model. Thus, the next steps would
require validation of the developed prediction equation
for Canadian cow carcasses using a separate commercial
population.
CONCLUSIONS
In the present study, D1 carcasses were comparable with
youthful carcasses (UTM and OTM). The addition of a
breakpoint based on dentition to facilitate international
trade results in carcass classes that had some distinguishing characteristics. UTM carcasses had larger
REA, thinner backfat, and higher sirloin butt and
short loin primal lean proportion with respect to OTM
carcass.
Abraham, H. C., Murphy, C. E., Cross, H. R., Smith, G. C. and
Franks, J. 1980. Factors affecting beef carcass cutability: an
evaluation of the USDA yield grades for beef. J. Anim. Sci. 5:
841851.
Atencio-Valladares, O., Huerta-Leidenz, N. and Jerez-Timaure,
N. 2008. Predicting beef carcass cutability in Venezuelan cattle.
Rev. Cient. FCV-LUZ 18: 704714.
Berg, R. T. and Butterfield, R. M. 1968. Growth patterns of
bovine muscle, fat and bone. J. Anim. Sci. 27: 611619.
Canada Gazette. 1992. Part II: Livestock and poultry carcass
grading regulations. Part III. Grade names and grade
standards for beef carcasses. [Online] Available: http://laws.
justice.gc.ca/eng/regulations/SOR-92-541/page-1.html [2011
Nov. 17].
Canfax. 2004. Annual report. Canfax Research Services,
Calgary, AB.
Canfax. 2011. Annual report. Canfax Research Services,
Calgary, AB.
Canfax. 2012. Weekly market outlook and analysis. Canfax
Research Services, Calgary, AB.
Canadian Beef Grading Agency. 1998. Beef carcass grading
reference. Canadian Beef Grading Agency. Calgary, AB.
26 pp.
Canadian Council on Animal Care. 1993. A guide to the care
and use of experimental animals. E. B. Olfert, B. M. Cross,
and A. A. McWilliams, eds. Vol. 1, 2nd ed. CCAC, Ottawa,
ON.
Canadian Meat Council. 1988. Food service meat manual.
2nd ed. Canadian Meat Council, Islington, ON. 43 pp.
Chaudhary, N., Anders, M., Dobson, C., Heikkila, R. and Bauer,
J. 2008. Benefits and costs of mandatory age verification for
cow/calf producers in Alberta. Government of Alberta, Alberta
Agriculture and Rural Development, Economics and Competitiveness Division, Edmonton, AB. 21 pp.
Can. J. Anim. Sci. Downloaded from pubs.aic.ca by Alberta Government Library on 03/08/13
For personal use only.
RODAS-GONZÁLEZ ET AL. * CANADIAN GRADE STANDARDS FOR COWS
Crouse, J. D., Dikeman, M. E., Koch, R. M. and Murphy, C. E.
1975. Evaluation of traits in the USDA yield grade equation
for predicting beef carcass cutability in breed group differing in
growth and fattening characteristic. J. Anim. Sci. 41: 548553.
Fredeen, H. T., Martin, A. H. and L’Hirondele, P. J.
1981. Tissue composition of Canada A beef carcasses and
implications in estimating dietary intake of fat and lean.
Can. J. Anim. Sci. 61: 883891.
Hilton, G. G., Tatum, J. D., Williams, S. E., Belk, K. E.,
Williams, F. L., Wise, J. W. and Smith, G. C. 1998. An
evaluation of current and alternative systems for quality
grading carcasses of mature slaughter cows. J. Anim. Sci. 76:
20942103.
Johnson, D. D. and Rogers, A. L. 1997. Predicting the yield
and composition of mature cow carcasses. J. Anim. Sci. 75:
18311836.
Jones, S. D. M., Tong, A. K. W. and Robertson, W. M. 1987.
The effects of carcass grade and sex on the lean content of beef
carcasses. Can. J. Anim. Sci. 67: 205208.
Kauffman, R. G., Van Ess, M. E., Long, R. A. and Schaefer,
D. M. 1975. Marbling: Its use in predicting beef carcass
composition. J. Anim. Sci. 40: 235241.
Killinger, K. M., Calkins, C. R., Umberger, W. J., Feuz, D. M.
and Eskridge, K. M. 2004. Consumer sensory acceptance and
value for beef steaks of similar tenderness, but differing in
marbling level. J. Anim. Sci. 82: 32943301.
Lawrence, T. E., Whatley, J. D., Montgomery, T. H. and
Perino, L. J. 2001. A comparison of the USDA ossificationbased maturity system to a system based on dentition. J. Anim.
Sci. 79: 16831690.
Lee, J. M., Yoo, Y. M., Park, B. Y., Chae, H. S., Hwang, I. H.
and Choi, Y. I. 2005. A research note on predicting the carcass
yield of Korean native cattle (Hanwoo). Meat Sci. 69: 583587.
Neely, T. R., Lorenzen, C. L., Miller, R. K., Tatum, J. D.,
Wise, J. W., Taylor, J. F., Buyck, M. J., Reagan, J. O. and
Savell, J. W. 1998. Beef customer satisfaction: Role of cut,
USDA quality grade, and city on in-home consumer ratings. J.
Anim. Sci. 76: 10271033.
107
O’Mara, F. M., Williams, S. E., Tatum, J. D., Hilton, G. G.,
Pringle, T. D., Wise, J. W. and Williams, F. L. 1998. Prediction
of slaughter cow composition using live animal and carcass
traits. J. Anim. Sci. 76: 15941603.
Robelin, J. 1986. Growth of adipose tissues in cattle; partioning between depots, chemical composition and cellularity.
A review. Livest. Prod. Sci. 14: 349364.
Rude, J., Carlberg, J. and Pellow, S. 2007. Integration to
fragmentation: Post-BSE Canadian cattle markets, processing
capacity, and cattle prices. Can. J. Agric. Econ. 55: 197216.
SAS Institute, Inc. 2003. SAS/STAT user’s guide: Statistics.
SAS Institute, Inc., Cary, NC.
Savell, J. W., Branson, R. E., Cross, H. R., Stiffler, D. M.,
Wise, J. W., Griffin, D. B. and Smith, G. C. 1987. National
consumer retail beef study: Palatability evaluations of beef loin
steaks that differed in marbling. J. Food Sci. 52: 517519, 532.
Smith, G. C., Berry, B. W., Savell, J. W. and Cross, H. R. 1988.
USDA maturity indices and palatability of beef rib steaks. J.
Food Qual. 11: 113.
Smith, G. C., Cross, H. R., Carpenter, Z. L., Murphey, C. E.,
Savell, J. W., Abraham, H. C. and Davis, G. W. 1982.
Relationship of USDA maturity groups to palatability of
cooked beef. J. Food Sci. 47: 11001107.
Stelzleni, A. M., Patten, L. E., Johnson, D. D., Calkins, C. R.
and Gwartney, B. L. 2007. Benchmarking carcass characteristics and muscles from commercially identified beef and dairy
cull cow carcasses for WarnerBratzler shear force and sensory
attributes. J. Anim. Sci. 85: 26312638.
United States Department of Agriculture. 1989. Official United
States standards for grades of carcass beef, United States
Department of Agriculture, Agricultural Marketing Service,
Washington, DC.
Van Donkersgoed, J., Jewison, G., Bygrove, S., Gillis, K.,
Malchow, D. and McLeod, G. 2001. Canadian beef quality
audit 199899. Can. Vet. J. 42: 121126.
Van Sickle, D. C. 1985. Control of postnatal bone growth.
J. Anim. Sci. 61: 7691.