Transcript Animal Selection and Evaluation

Animal Selection
and Evaluation
Carcass Evaluation
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Why Evaluate Carcasses?

A complete understanding of the factors that
affect carcass quality and yield grade is
essential to every producer, feeder, buyer,
and consumer of livestock and meat.
 With increased use of value based marketing
systems, the ability to predict the carcass
merit of market animals becomes even more
imperative.
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Beef Carcass Evaluation and
Grading
The first step in beef carcass evaluation
is the determination of class or sex
group.
 Class determination of beef carcasses
is based on evidences of maturity and
sex condition at the time of slaughter.
 In addition to class, the bovine specie is
subdivided into kind.

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Determination of Kind

The differentiation between veal, calf,
and beef carcasses is made primarily
on the basis of the color of lean,
although such factors as texture of lean,
character of the fat, color, size, and
ossification of the bone and cartilages,
and the general contour of the carcass
are also given consideration.
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Determination of Kind Con’t

Veal
– Veal carcasses have a grayish pink to dark
grayish pink color of lean that is smooth
and velvety in texture.
– They also have a slightly soft, pliable
character of fat, and narrow and very red
ribs.
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Determination of Kind Con’t

Calf
– Calf carcasses have a grayish red to
moderately red color of lean, a flakier type
of fat, and somewhat wider ribs with less
pronounced evidences of red color.
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Determination of Kind Con’t

Beef
– Beef carcasses have evidences of more advanced
maturity.
– Color of lean is moderately red in young beef
carcasses and may be very dark red in mature
beef carcasses.
– Fat is flaky and ribs show evidence of flatness and
are slightly red in color in young beef carcasses.
– Cartilage shows some evidence of ossification in
the sacral and lumbar regions compared to calf
carcasses.
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Determination of Class
Since the quality grade standards and
some of the qualitative properties (i.e,
color, texture, etc.) of beef carcasses
vary by class, identification of class is
necessary in carcass evaluation.
 The following characteristics are used to
identify and categorize beef carcasses
into their respective classes.

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Determination of Class Con’t.

Steers
– Identified by the typically rough and
irregular shaped fat deposit in the cod
region and the presence of a relatively
small pizzle eye (white disc caudal to the
aitch bone; it is the severed proximal
portion of the penis).
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Determination of Class Con’t.

Bullocks
– Identified by their disproportionately heavy
development of rounds, noticeable crests, thickly
fleshed chucks, and large prominent pizzle eyes.
– Bullock carcasses usually have a noticeably
developed small, round muscle adjacent to the hip
bone commonly referred to as the jump muscle.
(May be covered with fat.)
– Scrotal fat is typically rough and irregular in shape
like that of steers and bulls. The appearance of
this fat deposit of steers, bullocks, and bulls
contrasts the smooth fat deposit of the udder in
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heifers.
Determination of Class Con’t.

Bullocks Con’t.
– The lean of bullocks is usually darker and coarser
in texture than that of steers, but usually it is not
as dark or as coarse as that from bulls.
– The distinction between bullock and bull
carcasses is based solely on their evidences of
skeletal (bone and cartilage) maturity with bullocks
being the younger of these two classes.
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Determination of Class Con’t.

Bulls
– Identified by their disproportionately heavy
development of rounds, noticeable crests, thickly
fleshed chucks, and large prominent pizzle eyes.
– Noticeably developed jump muscle. (May be
covered with fat.)
– Scrotal fat is typically rough and irregular in shape
like the fat found in steers and bullocks, which
contrasts the smooth udder fat of heifers.
– The lean is usually dark red and coarse textured.
– The bone characteristics of bulls show evidence of
advancing skeletal maturity.
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Determination of Class Con’t.

Heifers
– Identified by smooth, uniform fat deposit in the
udder region, the absence of the pizzle eye, a
slightly larger pelvic cavity, and a straighter aitch
bone than steers.
– Heifer carcasses have a large, bean-shaped bald
spot (gracilis muscle) because the muscle has
less fat covering it than steers.
– Less heavily muscled.
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Determination of Class Con’t.

Cows
– Identified by their relatively large pelvic cavity and
nearly straight aitch bone (accommodates
calving.)
– Udder is usually removed.
– Hips of cow carcasses usually range from slightly
prominent to very prominent.
– Most cows are old when marketed, and in such
carcasses the sacral vertebrae are fused and
appear as essentially one bone.
– All bones are usually hard, white, and the cartilage
associated with the vertebrae and aitch bone are
completely ossified, except for the buttons which
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may not be completely ossified.
Illustration Showing Presence of
Pizzle Eye, Udder, Cod and Scrotal
Fat, Shape of Aitch Bone, Gracilis
Muscle and Width of Pelvic Cavity.
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Illustration Showing the
Conformation of a Heifer, Steer,
and Bullock Carcass.
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Weight

Hot carcass weight is almost
always obtained on beef carcasses
just before chilling, and chilled
carcass weight is usually calculated
from hot carcass weight.
 Hot carcass weight is 1 to 2%
higher than chilled carcass weight.
 Chilled carcass weight =Hot
carcass weight x .985
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Dressing Percentage

Chilled carcass weight is divided by live
weight and multiplied by 100 to obtain
dressing percentage.
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Ribbing
Ribbing is the process of cutting one or
both sides of the carcass between the
12th and 13th rib to expose the ribeye
(longissimus) muscle, marbling, and fat
thickness.
 Beef carcasses must be ribbed before
they can be graded.

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Illustration Showing Site of the
12th Rib Fat Thickness
Measurement
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Beef Quality Grading

Beef carcass quality grade is based upon two
major factors: (1) degree of marbling and (2)
degree of maturity.
 In addition to these factors, color, texture, and
firmness of lean in the ribeye muscle are
considered in determining final quality grade.
 The beef quality grades are U.S.D.A. Prime,
Choice, Select, Standard, Commercial, Utility,
Cutter, and Canner.
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Beef Quality Grading Con’t.

Marbling
– Marbling is the intermingling or dispersion of fat
within the lean (intramuscular fat).
– Marbling is estimated on the lean cut surface of
the ribeye muscle at the 12th rib interface.
– The grade standards specify more marbling for the
high grades (U.S.D.A. Prime and Choice) than in
the lower grades (U.S.D.A. Select and Standard).
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Beef Quality Grading Con’t.

Marbling Con’t.
– Amount of marbling in the eye muscle is divided
into ten degrees:
1. Devoid
6. Modest
2. Practically devoid 7. Moderate
3. Traces
8. Slightly abundant
4. Slight
9. Moderately abundant
5. Small
10. Abundant
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Beef Quality Grading Con’t.

Marbling Con’t.
– Marbling is an indicator of eating quality,
however, as it increases caloric content
also increases.
– Marbling is associated with length of time
on feed, type of feed, and genetic capacity
for laying down this fat deposit.
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Illustrations of Ribeye Muscle at
the 12th Rib Showing Marbling
Necessary for Quality Grades
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Beef Quality Grading Con’t.

Maturity
– Eating quality characteristics (tenderness,
juiciness, and flavor) are related to animal age.
– Maturity refers to the physiological age of cattle
rather than to the chronological age (usually
unknown).
– Physiological indicators of maturity include bone
characteristics, ossification of cartilage, and color
and texture of the ribeye muscle.
– Cartilage ossifies (becomes bone) and bone
whitens (becomes harder, flinty-like and white)
with increasing age.
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Beef Quality Grading Con’t.

Maturity Con’t.
– Color of lean becomes darker due to accumulation
of myoglobin and texture becomes coarser with
age.
– There are five maturity groups and they are
designated by the letters A, B, C, D, and E.
• A and B maturities are from young cattle and carcasses
from mature cattle are designated C, D, and E.
• Because of ossification that has occurred in the bones
and cartilage, these C, D, and E maturity carcasses are
called “hard boned.”
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Illustration Showing Carcass
Maturity


Left: A maturity carcass
– bones have red color
and buttons show no
ossification.
Right: E maturity
carcass – bones are
whiter and buttons
(indicated by arrows)
are completely ossified.
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Illustration of Ribeye Muscle
Showing Normal, Slightly Dark
and Dark Color of Lean
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Relationship of Marbling and
Maturity as used in Determining
Final Beef Quality Grade
(Area in Black is Standard)
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Beef Yield Grading

Yield grade is a numerical value from 1 to 5 based
upon the yield of boneless closely trimmed
(approximately .3 in.), retail cuts from the round, loin,
rib, and chuck.
 These four whole sale cuts make up about 75% of
the weight, but about 90% of carcass value.
 The following factors have the greatest influence on
carcass cutability:
a.
fat thickness at 12th rib
b.
ribeye area (measured with grid)
c.
hot carcass weight
d.
percentage kidney, pelvic, and heart fat 31
(KPH)
Illustration of Location of Beef
Primal Cuts
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